Vicor Micro Family of DC-DC Converter User Manual

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Design Guide & Applications Manual

For Maxi, Mini, Micro Family DC-DC Converter and Accessory Modules

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Table of Contents

Maxi, Mini, Micro Family DC-DC Converters Section Pages

High Density DC-DC Converter Technology 1 2 – 4

Control Pin Functions and Applications 2 5 – 11

Design Requirements 3 12 – 17

EMC Considerations 4 18 – 19

Current Sharing in Power Arrays 5 20 – 24

Thermal Performance Information 6 25 – 30

Accessory Modules

Autoranging Rectifier Module (ARM) 7 31 – 35

Filter / Autoranging Rectifier Module (FARM) 8 36 – 40

Modular AC Front-end System (ENMod) 9 41 – 47

High Boost HAM 10 48 – 52

Filter Input Attenuator Module (FIAM) Family 11 53 – 55

Output Ripple Attenuator Module (MicroRAM) 12 56 – 61

Recommended Soldering Methods

Lead Free Pins (RoHS) 13 62 – 66

TIn Lead Pins 14 67 – 71

Mounting Options

Surface Mount Socketing System (SurfMate) 15 72 – 75

Through-hole Socket-mount System (InMate) 16 76 – 79

Glossary of Technical Terms 17 80 – 87

Maxi, Mini, Micro Design Guide Rev 4.9 vicorpower.com

Page 1 of 88

Apps. Eng. 800 927.9474 800 735.6200

Page 3

1. High Density DC-DC Converter Technology

AC-DC Products

DC-DC Products

Universal 85 – 264 Vac

Autoranging 90 – 132 Vac 180 – 264 Vac

Autoranging 115 – 230 Vac Input

Nominal Input 18 – 425 Vdc

28 Vdc, 48 Vdc, 270 Vdc

24 Vdc, 28 Vdc, 48 Vdc

Harmonic Attenuator Module Unity Power Factor

Up to 675 W per module

Filter / Autoranging Rectifier Module

Up to 1,000 W

Autoranging Rectifier Module

Up to 1,500 W

Front-end System for EN Compliance

Up to 550 W

Transient Protection, Inrush Current Limiting EMI Filter

Up to 25 A

Active EMI Filter Up to 576 W @ 48 V

DC-DC Converter

Up to 600 W per module 1 – 54 Vdc

INIHAM

FARM3

QPI

DC-DC Converter

Up to 300 W per module 1 – 48 Vdc

DC-DC Converter

Up to 150 W per module 1 – 48 Vdc

Single wire paralleling for high power, fault tolerant arrays.

Output Ripple Attenuation Module combines active and passive filtering.

QPO provides active filtering to achieve differential noise attenuation.

QPO

DC-DC Products

High Boost

HAM

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

Design Guide & Applications Manual

The Maxi, Mini, Micro Family of DC-DC converters are an integral part of the company’s overall component power solution strategy, (Figure 1–1), which includes advanced

actory and design automation. The modules are available

f in an unlimited variety of standard versions, to the extent

hat the line between custom and standard DC-DC

t converter bricks becomes almost indistinguishable.

The design of the control, magnetic, switching, and packaging elements of the module resulted in a component with a power density of up to 120 W/in

(7,3 W/cm3) in three package sizes:

Maxi 4.6" x 2.2" x 0.5" (117 x 55,9 x 12,7 mm) Mini 2.28" x 2.2" x 0.5"(57,9 x 55,9 x 12,7 mm) Micro 2.28" x 1.45" x 0.5"(57,9 x 36,8 x 12,7 mm)

The modules have one-third the number of parts of their predecessors.

While the natural by-products of this reduction in parts count has improved reliability and lower cost, the extra space also means that the bulk of the converter can now

be devoted almost exclusively to the power train (i.e., the magnetic and switching elements at the core of the design).

Resistors can be used to trim the output voltage up or down, if necessary. Six pin styles, three baseplate options, and a variety of data collection and reporting options are available. The devices have an operating temperature range of –55°C to 100°C and come in five product grades – E, C, T, H, and M.

Other specifications include a typical no-load to full-load regulation of ±0.5%, a programmable output of 10% to 110%, conversion efficiencies of up to 92% depending on the voltage combination and power level chosen, and an input-to-output isolation test voltage of 3,000 Vrms (4,242 Vdc). All models are parallelable with N+M fault tolerance and current sharing. Paralleling architectures feature DC or AC-coupled interface.

Figure 1–1 — Component power solutions with the Maxi, Mini, Micro Family

Maxi, Mini, Micro Design Guide Rev 4.9 vicorpower.com

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Design Guide & Applications Manual

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

1. High Density DC-DC Converter Technology

Key to the design of Maxi, Mini, Micro converters is its high level of component-level integration. (Figure 1–2) With the aid of hybrid technology, the device packs all

ontrol functions and active circuitry into two (primary

c and secondary side) ICs occupying a total volume of less

han 1/10 in

(

1,6 cm

each.

)

With Maxi, Mini, Micro devices, the plated-cavity transformer cores use copper armor, plated onto the ferrite core, to more closely confine the magnetic flux to couple widely separated primary and secondary windings. The wider separation provides greater isolation and therefore lowers input-to-output parasitic capacitance and noise. The plated cavity also serves to conduct heat away from the transformer to the baseplate, thus increasing the power-handling capability of the power train and minimizing temperature rise.

The power-train assembly is contained between the baseplate and a terminal-block assembly, with input and

output pins recessed. This allows the converter body to be mounted into an aperture in the PCB to reduce the height above board. The modules may be wave soldered or

lugged into through-hole or surface-mount sockets.

The Maxi, Mini, Micro devices use a proprietary, low-noise, integrated power device that has an order of magnitude lower parasitic effect.

The advances made in the overall design of the Maxi, Mini, Micro Family DC-DC converters have been complemented by equally significant advances in the technology used to manufacture them. Vicor invested in a custom, fully-automated assembly line specifically designed for the assembly of Maxi, Mini, Micro power components. To further augment its Maxi, Mini, Micro product offering, Vicor has created an online user-interface tool,

PowerBenchTM, that allows customers to specify DC-DC

module requirements anytime, anywhere via the internet.

Bottom View

• Standard MLP power devices

• Efficient pick-and-place assembly

Top View

• Surface mount components for greater manufacturing efficiency

• Standard reflow process

Figure 1–2 — Maxi assembly shows high level of integration.

Maxi, Mini, Micro Design Guide Rev 4.9 vicorpower.com

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Apps. Eng. 800 927.9474 800 735.6200

Baseplate

• Simplified baseplate construction

Serial No. & Date Code

Complete Assembly

• Insert molded terminal block for more accurate pin positioning

• One piece cover with label

• Encapsulated for superior thermal performance

Model Number

Page 5

1. High Density DC-DC Converter Technology

+ OUT

+ SENSE*

– OUT

– SENSE*

+ IN

– IN

Primary Control IC

Secondary Control IC

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

Design Guide & Applications Manual

The Maxi, Mini, Micro’s ZCS / ZVS power-processing architecture (Figure 1–3) enables efficient, low-noise, high-frequency operation. The main switch is common

rain for improved thermal and noise management,

d the reset switch located within the primary control IC

s common source for ease of control.

The control circuitry is integrated into two (primary and secondary side) ICs. The result is a significant reduction in

parts with the ensuing savings in cost and increase in reliability. This integration also provides extra room for the power train.

Maxi, Mini, Micro transformers place the primary and secondary windings far apart, but contain the magnetic flux using a copper armor plated onto the ferrite core. The armor also conducts excess heat to the baseplate.

Figure 1–3 — Maxi, Mini, Micro: Basic power train and control (*Not included in Micro family)

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Design Guide & Applications Manual

+IN

–IN

4 kΩ

"Module

Enabled"

+IN

–IN

Disable

Disable = PC <2.3 V

+OUT

–S

– O U T

+IN

–IN

Input Undervoltage

2-20 ms typ.

)

Auto

Restart

5.7 Vdc

(0-3 mA)

50 Ω

SW2

SW3

1.23 Vdc

6 K

1 K

SW1

W1, 2, & 3 shown in

"Fault" position

Input Overvoltage (See Note 1) Overtemperature Module Faults

Not applicable for 300 Vdc input family

1 M

Input Undervoltage Input Overvoltage

[a]

Over Temperature Module Faults

2-20 ms typ.

f(VIN)

Auto

Restart

5.7 Vdc

(0-3 mA)

50 Ω

SW2

SW3

1.23 Vdc

6 K

1 K

SW1

SW1, 2, & 3 shown

in "Fault" position

+OUT

–OUT

+IN

–IN

[a]

Not applicable for 300 Vdc Input family

1 M

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

PRIMARY CONTROL (PC PIN)

2. Control Pin Functions and Applications

Module Enable / Disable. The module can be disabled

y pulling the PC below 2.3 V with respect to the –Input.

b This should be done with an open-collector transistor, relay, or optocoupler. Multiple converters may be disabled with a single transistor or relay via “ORing” diodes. When using a mechanical switch or relay to control the PC pin, please ensure that the contacts are properly debounced with a capacitor (10 nF max.) to avoid switch bounce.

: Do not exceed a repetitive on / off rate of

NOTE 1 Hz to the PC pin or input voltage pins.

An optocoupler must be used when converters are located on different PC boards, when a common-mode inductor is used directly at the module input, or when the distance between the converters would cause excessive voltage drops. Under no circumstances should the PC pin be pulled negative more than a diode drop below the module –IN. (Figure 2–1) When the PC pin is pulled low the PC current will pulse similar to the PC voltage shown in Figure 2–4. When the outputs of two or more converters are connected in a parallel array to increase system power the converters should be “group enabled” to ensure that all the converters start at the same time. The PC pins of all converters in the array should be controlled by an external

circuit which will enable the converters once the input

oltage is within the normal operating range.

Primary Auxiliary Supply. At 5.75 V, the PC can source

p to 1.5 mA. In the example shown in Figure 2–3, PC

u powers a LED to indicate the module is enabled. Another example of an isolated on-state indicator is shown in Figure 2–5.

NOTE

: When the module has detected a fault or when the input voltage is above or below the normal operating range the PC voltage will pulse.

Module Alarm. The module contains “watchdog” circuitry that monitors input voltage, operating temperature, and internal operating parameters. (Figures 2–2a and 2–2b) If any of these parameters is outside their allowable operating range, the module will shut down and PC will go low. (Figure 2–4) Then PC will periodically go high and the module will check to see if the fault (as an example, input undervoltage) has cleared. If the fault has not been cleared, PC will go low again and the cycle will restart. The SC pin will go low when a fault occurs and return to its normal state after the fault has been cleared. An example of using a comparator for monitoring on the secondary is shown in Figures 2–6a and 2–6b.

Figure 2–1 — Module Enable / Disable

Figure 2–2b — PC and SC module alarm logic (Micro)

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Figure 2–2a — PC and SC module alarm logic (Maxi / Mini)

Apps. Eng. 800 927.9474 800 735.6200

Figure 2–3 — LED on-state indicator

Page 7

2. Control Pin Functions and Applications

+IN

–IN

Optocoupler

4 kΩ

Alarm

1.00V

+OUT

–S

–OUT

omparator

Alarm

1.0 0 V

+OUT

–OUT

+IN

–IN

Comparator

2–20 ms typ.

Fault

1.23 V

5.7 V

0 μs typ.

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

Design Guide & Applications Manual

Figure 2–4 — PC / SC module alarm timing Figure 2–5 — Isolated on-state indicator

Figure 2–6a — Secondary side on-state (Maxi / Mini) Figure 2–6b — Secondary side on-state (Micro)

PARALLEL BUS (PR PIN)

A unique feature has been designed into Vicor Maxi, Mini, Micro converter modules that facilitates parallel operation for power expansion or redundancy. The PR pin is a bidirectional port that transmits and receives information between modules. The pulse signal on the parallel (PR) bus serves to synchronize the high-frequency switching of each converter which in turn forces them to load share. These modules possess the ability to arbitrate the leadership role; i.e., a democratic array. The module that assumes command transmits the sync pulse on the parallel bus while all other modules on the bus listen. In the event of a failure of the lead module, the array “elects” a new leader with no interruption of the output power.

Connection methods for the PR bus include:

1. AC-coupled single-wire interface: All PR pins are

connected to a single communication bus through

0.001 µF (500 V) capacitors. This interface supports current sharing and is fault tolerant except for the communication bus. (Figure 2–7) This method may normally be used with a maximum of three converters.

2. Transformer-coupled interface: Modules or arrays of

modules may also be interfaced to share a load while providing galvanic isolation between PR pins via a transformer-coupled interface. For large arrays, buffering may be required. The power source for the buffer circuit may be derived from the PC pins. For arrays of four or more modules, the transformer coupled interface is recommended. (Figure 2–8)

Maxi, Mini, Micro Design Guide Rev 4.9 vicorpower.com

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Page 8

Design Guide & Applications Manual

+IN

–IN

+IN

–IN

Module 2

Module 1

Parallel

Bus

–

0.2 µF

0.001 µF

0.2 µF

0.001 µF

Low inductance ground plane or bus

4.7 nF

Z1*

+IN

–IN

+IN

–IN

Module 2

Module 1

–

0.2 µF

Parallel

Bus

4.7 nF

Z1*

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

PARALLEL OPERATION CONSIDERATIONS

2. Control Pin Functions and Applications

are must be taken to avoid introducing interfering signals

C (noise) onto the parallel bus that may prevent proper load sharing between modules, instability, or module failure. One possible source of interference is input ripple current

onducted via the + and –Input power pins. The PR signal

c and DC power input share a common return, which is the –Input pin. Steps should be taken to decouple AC components of input current from the parallel bus. The input to each converter (designated as + and – pins on the input side of the module) should be bypassed locally with a

0.2 µF ceramic or film capacitor. This provides a shunt path for high frequency input ripple current. A Y-rated 4,700 pF capacitor should be connected between both the + and –Input pins and baseplate of each module, thus creating a shunt path for common-mode components of current. Attention to the PC board artwork should minimize the parasitic impedance between –Input pins of parallel modules to ensure that all PR pins are referenced to the same potential, or use a transformer coupled interface. Modules should be placed physically close to each other and wide copper traces (0.75 in./19 mm, 2 oz. copper) should be used to connect power input pins. A dedicated layer of copper is the ideal solution.

Some applications require physical separation of paralleled modules on different boards, and/or input power from separate sources. For applications using separate sources, please refer to the “Hot-Swap Capability Eliminates Downtime” application note on Vicor’s website. In these cases, transformer coupling of the PR signal, per Figure 2–8, is required to prevent inter-module common-mode noise

rom interfering with the sync pulse transmission. High-

f speed buffering may be required with large arrays or if the distance between modules is greater than a few inches. This is due to the fact that all modules, except the one

hat’s talking, are in the listening mode. Each listener

t presents a load to the master (talker), which is approximately 500 Ω shunted by 30 pF capacitance. Long leads for the interconnection introduce losses and parasitic reactance on the bus, which can attenuate and distort the sync pulse signal. The bandwidth of the bus must be at least 60 MHz and the signal attenuation less than 2 dB. In most cases, transformer coupling without buffering is adequate. Many applications may benefit from the addition of Z1, in series with the PR Pin of each converter. A low Q 33 Ω @ 100 Mhz ferrite bead or a 5 - 15 Ohm resistor may be used to improve the PR signal waveform. Although this is not a requirement, it can be very helpful during the debug stage of large converter arrays to help improve the PR pulse wave shape and reduce reflections. Again, careful attention must be given to layout considerations. When the outputs of two or more converters are connected in a parallel array to increase system power the converters should be “group enabled” to ensure that all the converters start at the same time. The PC pins of all converters in the array should be controlled by an external circuit which will enable the converters once the input voltage is within the normal operating range. Please consult with

Applications Engineering at any Vicor Technical Support Center for additional information.

Figure 2–8 — Transformer-coupled interface

Apps. Eng. 800 927.9474 800 735.6200

Figure 2–7 — AC coupled single-wire interface

Maxi, Mini, Micro Design Guide Rev 4.9 vicorpower.com

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Page 9

2. Control Pin Functions and Applications

Module 2

Module 1

Module N+1

+OUT

–S

–OUT

Load

–

–S

+OUT

–S

–OUT

+OUT

–S

–OUT

+OUT

–S

–OUT

+Sense from

other modules

in the array

+OUT

–OUT

L O A D

Plane

Ground

Plane

Module #1 Designated Master

Module #2 trimmed down 2 %

Module #3 trimmed down 4 %

+OUT

–OUT

+OUT

–OUT

CONTROL FUNCTIONS AND OUTPUT CONSIDERATIONS

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

Design Guide & Applications Manual

arallel Operation (PR Pin). The PR pin supports paral-

leling for increased power with N+1or N+M redundancy. Modules of the same part number will current share if all PR pins are suitably interfaced. Figures 2–9 and 2–10

how connections for the Maxi and Mini modules; Figure

s 2–11 shows connections for Micro array. Applications containing two or more Micro modules must define a designated master (talker) by stagger trimming the output voltage of each subsequent module down by at least 2%, or setting the remaining Micro modules in the system as designated listeners by connecting the SC pin to the negative output pin.

PR Pin Considerations. When paralleling modules, it is important that the PR signal is communicated to all modules within the parallel array. Modules that do not receive a PR pulse in a parallel array will not current share and may be damaged by running in an over-power condition.

The +Out and –Out power buses

• hould be designed to minimize and

s balance parasitic impedance from each module output to the load.

• The +Sense pins should be tied to the same

point on the +Out power bus; (Figure 2-10) the –Sense pins should be tied to the same point on the –Out power bus.

• At the discretion of the power system

designer, a subset of all modules within an array may be configured as slaves by shorting SC to –S.

• ORing diodes may be inserted in series

with the +OUT pins of each module to provide module output fault tolerance.

Figure 2–9 — N+1 module array output connections (Maxi and Mini)

ll modules in an array must be of the same part

A number.Series connection of outputs is accomplished without connecting the PR pins and allowing each module to regulate its own output voltage. Since the same current

asses through the output of each module with the series

p connection, power sharing is inherent. Series connection of inputs requires special precautions, please contact Applications Engineering for assistance.

Array Output Overvoltage Protection (OVP). In order to maintain the highest possible uptime of a parallel array the converters use an output overvoltage protection system (OVP) that is highly resistant to false tripping. For the converter to shut down due to an OVP condition two conditions must be satisfied (logical AND);

1. The voltage at the output terminals must be greater than the OVP set point.

2. The secondary control IC within the converter must be requesting a power conversion cycle from the internal primary control IC.

By using this logic, false tripping of individual converters due to externally induced OVP conditions such as load dumps or, being driven by an external voltage source at the output terminals is minimized.

Modules connected in a parallel array rely on the active master module for OVP of the entire array. Modules acting as boosters (slaves) in the array are receiving external requests for power conversion cycles (PR pulse) and will not shut down from an OVP condition. Therefore it is imperative that the + and -Output pins of modules connected in a parallel array never

be allowed to become open circuited from the output bus. An open circuit at the output terminals will result in terminal voltages far in excess of the normal rating causing permanent damage to the module and possible hazardous conditions.

Figure 2–10 — ORing diodes connections (Maxi and Mini)

Maxi, Mini, Micro Design Guide Rev 4.9 vicorpower.com

Page 8 of 88

Figure 2–11 — Parallel module array output connections (Micro)

Apps. Eng. 800 927.9474 800 735.6200

• The +Out and –Out power buses should be designed to minimize and balance parasitic impedance from each module output to the load.

• At the discretion of the power system designer, a subset of all modules within an array may be configured as slaves by shorting SC to –Out.

• Do not use output ORing diodes with parallel arrays of the Micro.

Page 10

Design Guide & Applications Manual

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

CONTROL FUNCTIONS, SECONDARY CONTROL (SC PIN)

utput Voltage Programming. The output voltage of

the converter can be adjusted or programmed via fixed resistors, potentiometers or DACs.

Trim Down. The converter is not

a constant power device; it has a constant current limit. Hence, available output power is reduced by the same percentage that output voltage is trimmed down. Do not exceed maximum rated output current. The trim down resistor must be connected to the –S pin (–Out pin on a Micro). (Figures 2–12a and 2–12b)

Trim Up. The converter is rated for a maximum delivered power. To ensure that maximum rated power is not exceeded, reduce maximum output current requirement in the application by the same percentage increase in output voltage. The trim up resistor must be connected to the +S pin (+OUT pin on a Micro.) Do not trim the converter above maximum trim range (+10%) or the output over voltage protection circuitry may be activated. (Figures 2–13a and 2–13b)

SC Pin and Output Voltage Trimming. If no connection is made to the SC pin, the SC pin voltage will be 1.23 V referenced to –S (-OUT pin on a Micro) and the output of the converter will equal the nominal output voltage. When the SC pin voltage is set by an external source such as a D/A converter, the % change in SC will be equal the % change in the output voltage.

For example, an application requires a +10, 0% (nominal), and a –15% output voltage adjustment for a 48 V output converter. Referring to the table below, the voltage that should be applied to the SC pin would be as follows:

2. Control Pin Functions and Applications

or systems that require an adjustable output voltage, it is

F good practice to limit the adjustment range to a value only slightly greater than that required. This will increase the adjustment resolution while reducing noise pickup.

It is recommended that the maximum rate of change applied to the SC pin be limited to 30 Hz, sinusoidal. Small step-up changes are permissible; however, the resultant change in the output voltage can create significant current demands due to charge requirements of both the internal and external output capacitance. In no case should the converter be driven beyond rated continuous output current. The response to programming a lower output voltage is limited by the energy stored in both the internal and external output capacitance and the load. The converter cannot sink current to lower the output voltage other than a minimal internal preload.

Contact to be dynamically trimmed.

Trimming resistor calculators are available on Vicor’s web site at http://www.vicorpower.com/powerbench. (Figure 2–16)

Resistor values can be calculated for fixed trim up, fixed trim down, and for variable trim up or down. In addition to trimming information, the web also includes design tips, applications circuits, EMC suggestions, thermal design guidelines and PDF data sheets for all Vicor products. Evaluation Boards (Figure 2–15) are available for the Maxi, Mini and Micro DC-DC converters.

Applications Engineering if the module’s output is

Change

VSC VOUT from

nominal

1.046 40.8 –15%

1.230 48.0 0%

1.353 52.8 +10%

Circuits such as op-amps and D/A converters, which directly drive the SC pin, should be designed to limit the applied voltage to the SC pin. It is also important to consider voltage excursions that may occur during initialization of the external circuitry. The external circuit must be referenced to the –S pin (–Out on Micro). See Figure 2–14 for remote sense implementation on Micro.

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Apps. Eng. 800 927.9474 800 735.6200

Page 11

2. Control Pin Functions and Applications

+OUT

–S

–OUT

Trim Up

Load

Error Amp

1 kΩ

.23 V

0.033 μF

1,000 (Vout –1.2 3) Vnom

1.23 (Vout – Vnom)

RU (ohms) =

– 1,000

Trim Up

Load

rror

1 kΩ

1.2 3 V

.033 µF

OUT

–OUT

–IN

1,000 (Vout –1.23 ) Vnom

1.23 (Vout – Vnom)

RU (ohms) =

– 1,000

––

2.55 k

1.00 k

TLV431

R7 21.0 k

0.22 µF

4.02 k

1.24 k

LM10

–S

+Out

–Out

R Load

PS2701

R11

36.5 k

1.65 k

470 pF

200 mV

Vcc

Gnd

Load

OUT

–S

–OUT

Trim Down

Error Amp

1 kΩ

1.2 3 V

.033 μF

1,000 Vout

Vnom – Vout

(ohms) =

Load

Trim Down

Error Amp

kΩ

1.2 3 V

0.033 μF

+OUT

–OUT

+IN

–IN

1,000 Vout Vnom – Vout

RD (ohms) =

1,000 (Vout –1.23) Vnom

1.23 (Vout – Vnom)

RU (ohms) =

– 1,000

Trim Up

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

Design Guide & Applications Manual

Figure 2–12a — Output voltage trim down circuit (Maxi/Mini)

Figure 2–13a — Output voltage trim up circuit (Maxi/Mini)

Figure 2–12b — Output voltage trim down circuit (Micro)

Figure 2–13b — Output voltage trim up circuit (Micro)

• This module is designed for point of load regulation, where remote sensing is not required. Active voltage drop compensator, as shown here, may be used in applications with significant distribution losses.

Please consult with the for additional information.

Figure 2–14 — Voltage drop compensation (Micro).

Maxi, Mini, Micro Design Guide Rev 4.9 vicorpower.com

Page 10 of 88

Micro Family Isolated Remote Sense Application Note

Apps. Eng. 800 927.9474 800 735.6200

Figure 2–15 — Evaluation Boards; Available for Maxi, Mini and Micro Family DC-DC converters

Page 12

Design Guide & Applications Manual

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

2. Control Pin Functions and Applications

EVALUATION BOARDS

• Three styles: Maxi, Mini or Micro

• Short pin and Long pin compatible

• Easy I / O and control connections

• Includes fusing and capacitors

• Can be paralleled for higher power arrays

DESCRIPTION PART NUMBER

Maxi board style 24644R Mini board style 24645R Micro board style 24646R

Figure 2–16 — Online trim calculator

Maxi, Mini, Micro Design Guide Rev 4.9 vicorpower.com

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Apps. Eng. 800 927.9474 800 735.6200

Page 13

3. Design Requirements

SAFETY CONSIDERATIONS

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

Design Guide & Applications Manual

using. Safety agency conditions of acceptability require

that the module positive (+) Input terminal be fused and the baseplate of the converter be connected to earth ground. The following table lists the acceptable fuse types

nd current rating for the Maxi, Mini, Micro Family of

a DC-DC converters. Safety Certifications on the Vicor web site should always be consulted for the latest fusing requirements.

Acceptable Fuse Types and Current Rating for the Maxi, Mini, Micro Family of Converters

Package Size Input Voltage Output Voltage Output Power Required Fuse

Maxi (A) 375 2 160 Bussmann PC-Tron 5A Maxi (A) 375 3.3 264 / 200 Bussmann PC-Tron 5A Maxi (A) 375 5, 8 400 / 300 Bussmann PC-Tron 5A Maxi (A) 375 12, 15, 24, 28, 32, 36, 48, 54 600 / 400 Bussmann PC-Tron 5A

Mini (B) 375 2 100 Bussmann PC-Tron 5A Mini (B) 375 3.3 150 / 100 Bussmann PC-Tron 5A Mini (B) 375 5, 8 200 / 150 Bussmann PC-Tron 5A Mini (B) 375 12, 15, 24, 28, 36, 48 300 / 200 Bussmann PC-Tron 5A

Micro (C) 375 2 50 Bussmann PC-Tron 3A Micro (C) 375 3.3 75 / 50 Bussmann PC-Tron 3A Micro (C) 375 5, 8 100 / 50 Bussmann PC-Tron 3A Micro (C) 375 12, 15, 24, 28, 36, 48 150 / 75 Bussmann PC-Tron 3A

Maxi (A) 300 2 160 Bussmann PC-Tron 5A Maxi (A) 300 3.3 264 / 200 Bussmann PC-Tron 5A Maxi (A) 300 5, 8 400 / 300 Bussmann PC-Tron 5A Maxi (A) 300 12, 15, 24, 28, 36, 48 500 / 400 Bussmann PC-Tron 5A

Mini (B) 300 2 100 Bussmann PC-Tron 5A Mini (B) 300 3.3 150 / 100 Bussmann PC-Tron 5A Mini (B) 300 5, 8 200 / 150 Bussmann PC-Tron 5A Mini (B) 300 12, 15, 24, 28, 36, 48 250 / 150 Bussmann PC-Tron 5A

Micro (C) 300 2 50 Bussmann PC-Tron 3A Micro (C) 300 3.3 75 / 50 Bussmann PC-Tron 3A Micro (C) 300 5, 8 100 / 50 Bussmann PC-Tron 3A Micro (C) 300 12, 15, 24, 28, 36, 48 150 / 75 Bussmann PC-Tron 3A

Maxi (A) 150 3.3 264 / 200 Bussmann ABC-8 Maxi (A) 150 5, 8 400 / 300 Bussmann ABC-8 Maxi (A) 150 12, 15, 24, 28, 36, 48 500 / 400 Bussmann ABC-8

Mini (B) 150 3.3 150 / 100 Bussmann PC-Tron 5A Mini (B) 150 5, 8 200 / 150 Bussmann PC-Tron 5A Mini (B) 150 12, 15, 24, 28, 36, 48 250 / 150 Bussmann PC-Tron 5A

Micro (C) 150 3.3 75 Bussmann PC-Tron 3A Micro (C) 150 5, 8 100 Bussmann PC-Tron 3A Micro (C) 150 12, 15, 24, 28, 36, 48 150 Bussmann PC-Tron 3A

Maxi (A) 110 3.3 200 / 150 Bussmann ABC-8 Maxi (A) 110 5, 8 300 / 200 Bussmann ABC-8 Maxi (A) 110 12, 15, 24, 28, 36, 48 400 / 300 Bussmann ABC-8

Mini (B) 110 3.3 100 / 75 Bussmann PC-Tron 5A Mini (B) 110 5, 8 150 / 100 Bussmann PC-Tron 5A Mini (B) 110 12, 15, 24, 28, 36, 48 200 / 150 Bussmann PC-Tron 5A

Micro (C) 110 3.3 50 Bussmann PC-Tron 3A Micro (C) 110 5, 8 75 Bussmann PC-Tron 3A Micro (C) 110 12, 15, 24, 28, 36, 48 100 Bussmann PC-Tron 3A

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Design Guide & Applications Manual

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

3. Design Requirements

Acceptable Fuse Types and Current Rating for the Maxi, Mini, Micro Family of Converters

Package Size Input Voltage Output Voltage Output Power Required Fuse

Maxi (A) 72 3.3 264 Bussmann ABC-12 Maxi (A) 72 5, 8 300 Bussmann ABC-12 Maxi (A) 72 12, 15, 24, 28, 36, 48 400 Bussmann ABC-12

Mini (B) 72 3.3 100 Bussmann ABC-8 Mini (B) 72 5, 8 150 Bussmann ABC-8 Mini (B) 72 12, 15, 24, 28, 36, 48 250 Bussmann ABC-8

Micro (C) 72 3.3 75 Bussmann PC-Tron 5A Micro (C) 72 5, 8 100 Bussmann PC-Tron 5A Micro (C) 72 12, 15, 24, 28, 36, 48 150 Bussmann PC-Tron 5A

Maxi (A) 48 3.3 264 Bussmann ABC-10 Maxi (A) 48 5, 8 400 Bussmann ABC-15 Maxi (A) 48 12, 15, 24, 28, 36, 48 500 Bussmann ABC-20

Mini (B) 48 2 100 Bussmann ABC-8 Mini (B) 48 3.3 150 Bussmann ABC-8 Mini (B) 48 5, 8 200 Bussmann ABC-10 Mini (B) 48 12, 15, 24, 28, 36, 48 250 Bussmann ABC-10

Micro (C) 48 2 50 Bussmann PC-Tron 5A Micro (C) 48 3.3 75 / 50 Bussmann PC-Tron 5A Micro (C) 48 5, 8 100 / 75 / 50 Bussmann ABC-8 Micro (C) 48 12, 15, 24, 28, 36, 48 150 / 75 Bussmann ABC-8

Maxi (A) 28 3.3 150 Bussmann ABC-25 Maxi (A) 28 5 175 Bussmann ABC-25 Maxi (A) 28 6.5, 8, 12, 15, 24, 28, 36, 48 200 Bussmann ABC-30

Mini (B) 28 3.3 75 Bussmann ABC-15 Mini (B) 28 5 75 Bussmann ABC-15 Mini (B) 28 12, 15, 24, 28, 36, 48 150 Bussmann ABC-15

Micro (C) 28 3.3 50 Bussmann ABC- 8 Micro (C) 28 5 50 Bussmann ABC-10 Micro (C) 28 12, 15, 24, 28, 36, 48 100 Bussmann ABC-10

Maxi (A) 24 3.3 264 / 200 Bussmann ABC-25 Maxi (A) 24 5, 8, 12, 15, 24, 28, 36, 48 400 / 300 Bussmann ABC-30

Mini (B) 24 3.3 150 / 100 Bussmann ABC-15 Mini (B) 24 5, 8, 12, 15, 24, 28, 36, 48 200 / 150 Bussmann ABC-15

Micro (C) 24 3.3 75 / 50 Bussmann ABC-8 Micro (C) 24 5, 8, 12, 15, 24, 28, 36, 48 100 / 50 Bussmann ABC-10

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3. Design Requirements

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

Design Guide & Applications Manual

The fuse must be in series with the positive (+) Input lead. Fusing the negative (–) Input lead does not provide adequate protection since the PR and PC terminals of the converter

re referenced to the –Input. If a fuse located in the

a –Input lead were to open, the PR and PC terminals could

ise to the potential of the +Input. This may damage any

r converter or circuitry connected to these pins. The fuse should not be located in an area with a high ambient temperature as this will lower the current rating of the fuse.

THERMAL AND VOLTAGE HAZARDS

Vicor component power products are intended to be used within protective enclosures. Vicor DC-DC converters work effectively at baseplate temperatures, which could be harmful if contacted directly. Voltages and high currents (energy hazard) present at the terminals and circuitry connected to them may pose a safety hazard if contacted or if stray current paths develop. Systems with removable circuit cards or covers which may expose the converter(s) or circuitry connected to the converters, should have proper guarding to avoid hazardous conditions.

The module pins are intended for PCB mounting either by wave soldering to a PCB or by insertion into one of the recommended PCB socket solutions. Use of discrete wire soldered directly to the pins may cause intermittent or permanent damage to the module; therefore, it is not recommended as a reliable interconnection scheme for production as a final released product. In addition, modules that have been soldered into printed circuit boards and have subsequently been removed should not be reused.

PC PIN

The PC pin should be used only to; disable the module, provide a bias to input referenced circuitry or communicate status of the module. The PC pin is referenced to the –Input pin. All circuits that connect to the PC pin must use the –Input as the reference. Do not break the connection between the –Input and the circuitry connected to the PC pin or damage to the module will result. Additional requirements include:

HIGH-POWER ARRAYS AND PR PIN

To simplify the implementation of large arrays, a subset of modules within the parallel array should be configured as boosters (listeners) by connecting the SC pin to the –S pin. Modules, which are configured as boosters, cannot assume the role of drivers (talkers) for N+M redundant arrays. Modules configured as boosters may be locally sensed.

Each module within the parallel array must be properly bypassed with capacitors. Film or ceramic types should be used across the input of the module and between each input lead and the baseplate. Modules having input sources, which are not connected to SELV sources, should use X-capacitors across the input and Y-capacitors from each input power pin to the baseplate. When in doubt about capacitor safety approvals, always consult with the governing safety regulatory agency or Vicor Applications Engineering.

A maximum of 12 modules may be directly connected in parallel. Please contact Vicor Applications Engineering for assistance with larger arrays.

The PR pin is referenced to the –In pin; therefore, all modules within the array must have a common lowimpedance connection between each –In pin. Special precautions are necessary if a PCB is not used for interconnection of modules, because the wiring impedance can be significant. Do not allow the connection between the –In pin and the –In bus to become disconnected as damage to the module will result.

Coupling transformers should be used to transmit the PR pulse if long distances between each module are anticipated or if the interconnection impedance of the –In leads is high or questionable. PR coupling transformer(s) should be used if the PR pulse exits the PCB. For example, an array constructed of multiple circuit cards plugged into a backplane with a number of converters on each card should have a PR coupling transformer at the entry point of each card; however, no coupling transformer would be required between each converter on the card of three or less converters on a single PCB. Do not externally drive the PR pin, connection to this pin is limited to Vicor module application only.

• Circuits that derive their power from the PC pin must

not exceed 1.5 mA.

• Do not drive the PC pin with external circuitry.

• Do not attempt to control the output of the converter

by PWM pulsing of the PC pin, or exceed a repetitive on / off rate of 1 Hz.

For applications where the converter will be disabled on a

INPUT SOURCE IMPEDANCE

The impedance of the source feeding the input of the module directly affects both the stability and transient response of the module. In general, the source impedance should be lower than the input impedance of the module by a factor of ten, from DC to 50 kHz.

regular basis or where capacitance is added to this pin, please contact Vicor

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Design Guide & Applications Manual

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

3. Design Requirements

To calculate the required source impedance, use the following formula:

Z = 0.1(VLL)2/ Pin

where: Z is required input impedance

s the low line input voltage

VLLi P

in is the input power of the module

Filters, which precede the module, should be well damped to prevent ringing when the input voltage is applied or the load on the output of the module is abruptly changed.

INPUT TRANSIENTS AND SURGES

The voltage applied to the input of the module must not exceed the ratings outlined in the data sheet. Protection devices such as Zener diodes and MOVs should be used to protect the module from short-duration transients. These shunt protection devices are effective only if the source impedance is high relative to the impedance of the protection device when it is conducting. For voltage surges where the abnormal voltage is present for a long period of time, shunt protection devices can easily be damaged by the power dissipated. For this type of condition, a voltage limiter in series with the input of the module may be the best solution. Vicor Applications Engineering can assist in recommending the appropriate type of protection for the module.

NOTE: Do not allow the rate of change of the input voltage to exceed 10 V/µs for any input voltage deviation.

SENSE LEADS (Mini and Maxi only)

The sense leads of the module must always terminate either directly to the output pins (local sense) or at the load (remote sense). When remote sense is used, the output wiring impedance in combination with the load impedance can cause significant loss of phase margin and result in oscillation and possible damage to the module, poor transient response, or activation of the output overvoltage protection. Long sense leads may require a compensation circuit for stability.

Protection circuitry is required if the possibility of reversed sense leads can occur. Please contact Vicor Applications Engineering for specific recommendations.

Do not

exceed 1 V between –S and –Out leads. This is an important consideration if the converter is used in a Hot-Swap application. ORing diodes, if used, should be located in the +Output lead to avoid exceeding this rating.

OUTPUT CONNECTIONS

For systems designed to charge batteries, subject the module output to dynamic loading, or loads that have large reactive components, please contact Vicor Applications Engineering to discuss your application in detail.

Do not externally drive the output of the module 10% above its nominal setpoint voltage.

Modules, that are used to charge batteries should be applied with a diode in series with the output of the module. The charge current must be externally controlled to ensure that the module is not operated in excess of its power or current rating.

Current-carrying conductors should be sized to minimize voltage drops.

Do not

use output ORing diodes with parallel arrays of

the Micro Family converters.

Output Overvoltage Protection (OVP). The OVP detection circuitry within the converter is highly resistant to false tripping. For the converter to shut down due to an OVP condition two conditions must be satisfied (logical AND);

1. The voltage at the output terminals must be greater than the OVP set point.

2. The secondary control IC within the converter must be requesting a power conversion cycle from the internal primary control IC.

By using this logic, false tripping of individual converters due to externally induced OVP conditions such as load dumps or, being driven by external voltage sources at the output terminals is minimized. The user should not test the OVP circuit by back driving the output terminals or by any other means as the OVP circuitry is fully tested as part of the inline manufacturing process.

OVERCURRENT PROTECTION

The Maxi, Mini, Micro converters incorporate a straightline type current limit. (Figure 3–1) As output current is increased beyond Imax, the output voltage remains constant and within its specified limits up to a point, IKNEE, which is typically 5 – 25% greater than rated current, Imax. Beyond IKNEE, the output voltage falls to Ishortcircuit. Typically, modules will automatically recover after the overcurrent condition is removed.

Do not

exceed the rated power of the converter. The total of the power consumed by the load plus the power lost in conductors from the converter to the load must be less than the output power rating of the converter.

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Page 17

3. Design Requirements

out

NEE

HORT CIRCUIT

out

Figure 3–1 — Typical Maxi, Mini, Micro current limiting

MAXIMUM OUTPUT CAPACITANCE

In general, adding external capacitance to the Maxi, Mini, and Micro’s output is not required. However, it is often common practice with power supply designs to add external capacitance to the converter output for attenuation of output ripple and / or improving dynamic load performance. The Maxi, Mini, Micro converters typically have a faster response to dynamic loads than other power solutions; hence, external capacitors may not be necessary. In addition, the output ripple and noise specification listed on the data sheet may be acceptable for many applications.

A general equation for determining the maximum recommended output capacitance is as follows:

Pout

C(farad) =Vout

(400x10

Vout

)

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

Design Guide & Applications Manual

ABSOLUTE MAXIMUM RATINGS

Please consult the latest module data sheets available on the Vicor website for maximum ratings concerning pin-topin voltages, isolation, temperature, and mechanical ratings.

GROUNDING OF BASEPLATE AND REFERENCING OF INPUT AND OUTPUT TERMINALS

The baseplate of the converter should always be connected to earth ground. If for any reason this is not possible in your application please consult with Vicor Applications Engineering for acceptable alternatives for your application.

The input and output leads of the converter should be referenced to the baseplate at some point to avoid stray voltages. For offline applications the input leads are often referenced to earth ground at the AC source ahead of the bridge rectifier. Either + or –Output terminal may be referenced to earth ground and the baseplate. “Floating” inputs or outputs should at a minimum have a highresistance divider to bleed off stray charges to avoid damage to the insulation system.

HIGH FREQUENCY BYPASSING

All Vicor converters must be bypassed for proper operation. (Figure 3–2) The minimum complement of high-frequency bypass capacitors must consist of the following:

• 0.2 µF ceramic or film type connected between

+In and –In.

• 4.7 nF Y-capacitor between +In and baseplate

and –In and baseplate.

• 10 nF ceramic or film capacitor between +Out and

baseplate and –Out and baseplate.

where: Pout is the output power of the converter

out is the nominal output voltage of the converter

All applications utilizing Maxi, Mini, Micro converters should be properly bypassed, even if no EMC standards need to be met. Bypass Vin and Vout pins to each module baseplate as shown in Figure 3–2. Lead length should

The capacitance value is not the absolute maximum value, but the value for which general application of the converter can be deemed appropriate. Testing will be required to ensure that the module is stable if this value is exceeded. Approximately 10X the value calculated will cause the converter to go into current limit at turn-on.

CAUTION:

If exceeding this value, it is recommended

that Vicor Applications Engineering be consulted.

be as short as possible. Recommended values vary depending on the front end, if any, that is used with the modules, and are indicated on the appropriate data sheet or application note. In most applications, C1 is a 4,700 pF Y-capacitor (Vicor P/N 01000) carrying the appropriate safety agency approval; C2 is a 4,700 pF Y-capacitor (Vicor P/N 01000) or a 0.01 µF ceramic capacitor rated at 500 V. In PC board applications, each of these components is typically small enough to fit under the module baseplate flange. For PCB mounting of the module. Please refer to Figures 3–3 and 3–4.

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Page 18

Design Guide & Applications Manual

0. 53

Ch as si s

0. 46

Onboard Mount

Cross-sectional view of pins

and mounting hardware

Inboard Mount

Cross-sectional view of pins

and mounting hardware.

Exploded View Exploded View

P/ N 20 265 Th er mM ate

Ex . V3 00 C1 2M75 BL

(L on g Sol de r Pin ,

Sl ot te d B as ep lat e)

P/ N 18 157 S ta ndo ff K it

PC B th ick nes s is

0. 06 2

" (

1. 5m m)

Tap ped # 4– 40 sc rew h ol e

Pa d a nd pl at ed th ro ughho le c onn ec te d t o ch as si s g roun d p la ne

P/ N 20 265 Th er mM ate

Ex . V3 00 C1 2M75 B

(S ho r t Sol de r Pin,

Sl ot te d B as ep lat e)

P/ N 18 151 S ta ndo ff K it

0. 06 2

" (1.5mm) PCB with

aperture to allow belly

th e mo dul e to re ce ss int o b oa rd

Tap ped # 4– 40 sc rew h ol e

Pa d a nd pl at ed th ro ughho le c onn ec te d t o ch as si s g roun d p la ne

13 ,5m m

11 ,7 mm

’

’’

+OUT

+IN

–IN

–OUT

Maxi, Mini, Micro

C-DC Converter

C1a

C1b

C2a

C2b

Baseplate grounded

Standoffs also provide necessary

mechanical support in order to

prevent mechanical stresses from

damaging the module during shock / vibration.

Standoff sitting on pad / plated through-hole that is connected to the chassis ground plane within the PCB.

Female-female standoffs are s

hown, however standoffs are

also available in male-female versions.

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

3. Design Requirements

Figure 3–2 — Minimum recommended bypassing for Maxi, Mini, and Micro; Keep all leads short.

Figure 3–3 — Recommended mounting method using standoffs

Figure 3–4 — Onboard vs. inboard mounting of (1/4 brick) Micro with slotted baseplate

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Page 19

4. EMC Considerations

FILTERING AND TRANSIENT PROTECTION

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

Design Guide & Applications Manual

ll switching power supplies generate potentially interfer-

A ing signals as a result of high-frequency, high-power switching. The Vicor power converter topology, to a large extent, addresses the problem at the source by the use of a quasi-resonant, zero-current switching (ZCS) and zerovoltage switching (ZVS) topology. The switching current waveform is a half sine wave that generates far less conducted and radiated noise in both frequency spectrum and magnitude. EMI filtering, if properly designed and implemented, reduce the magnitude of conducted noise an additional 40 – 60 dB, and as a result, the noise radiated by the power conductors is reduced proportionally.

BASIC GUIDELINES FOR SUCCESSFUL EMI FILTERING

1. Keep current loops small. The ability of a conductor to

couple energy by induction and radiation is reduced accordingly.

2. For conductor pairs, use wide (low Z) copper traces

aligned above and below each other.

3. Locate filters at the source of interference; i.e., close

to the power converter(s).

4. Filter component values should be chosen with

consideration given to the desired frequency range of attenuation. For example, capacitors are self-resonant at a certain frequency, beyond which they look inductive. Keep bypass capacitor leads as short as possible.

5. Locate components on the PCB with consideration

given to proximity of noise sources to potentially susceptible circuits. For example, the FIAM is an input line filter module that has been optimized for use with Maxi, Mini, and Micro DC-DC converters. When used in conjunction with the recommended external components and layout, it will significantly reduce the differential and common-mode noise returned to the power source. The FIAM meets the requirements of EN55022 “B”, FCC “B”, and Bellcore GR-001089CORE, Issue 2 when used with any combination of Maxi, Mini, and Micro converters up to the FIAM’s maximum rated current.

onducted noise on the input power lines can occur as

C either differential-mode or common-mode noise currents. Differential-mode noise, largely at low frequencies, appears across the input conductors at the fundamental switching frequency and its harmonics. Common-mode noise, which has mostly high-frequency content, is measured between the converter’s input conductors and ground.

The Vicor power converter being an electronic device may be susceptible to high levels of conducted or radiated emissions. It is the responsibility of the user to assess testing protocols in order to determine applicability of the converter in the intended application.

DC-DC converter inputs and outputs must be properly bypassed, to system chassis or earth. Bypass Vin and Vout pins to each DC-DC module baseplate. Capacitor lead length must be as short as possible. (Figure 4–1)

EMI filtering can be application dependent. A packaged filter module may not always be the appropriate solution, and the general practice of bypassing Vin and Vout may not produce optimal results. You may have to adjust the values depending on the severity of common-mode and differential-mode noise. (Figures 4–2 and 4–3)

Input transient suppression should be used in applications where source transients may be induced by load changes, blown fuses, etc. The level of transient suppression required will depend on the expected severity of the transients. A Zener diode, TRANSORB™, or MOV will provide transient suppression, act as a voltage clamp for DC input spikes, and provide reverse input voltage protection. The device voltage rating should be chosen above high-line voltage limits to avoid conducting during normal operation which would result in overheating.

Module shields that provide shielding around the belly (label side) of the Maxi, Mini, Micro are also available for applications that are highly noise sensitive. Module shield information is available on the Vicor website, see links provided, on the following page.

NOTE:

Acoustic Noise. Audible noise may be emitted from the module under no load, light load, or dynamic loading conditions. This is considered normal operation of the module.

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Page 20

Design Guide & Applications Manual

+IN

–IN

+OUT

–S

–OUT

C3*

4.7nF

.7nF

or C1 – C5, keep leads and connections short.

4.7nF

C4*

4.7nF

F1*

C1*

0.2µF

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

4. EMC Considerations

Figure 4–1 — Recommended bypassing capacitors must be in close proximity, i.e., have short lead length to be effective.

Figure 4–3 — V48B28H250BN with recommended bypass caps (330 µF across input)

Module Shield Information

Module shield for Maxi with threaded or through-hole baseplate P/N 30142

http://asp.vicorpower.com/CADPDF/H7CEX3.PDF

Figure 4–2 — V48B28H250BN without bypass caps (330 µF across input)

Module shield for Maxi with slotted baseplate P/N 30199

http://asp.vicorpower.com/CADPDF/HXE113.PDF

Module shield for Mini with threaded or through-hole baseplate P/N 30180

http://asp.vicorpower.com/CADPDF/UT55TT.PDF

Module shield for Mini with slotted baseplate P/N 30198

http://asp.vicorpower.com/CADPDF/HXE112.PDF

Module shield for Micro with threaded or through-hole baseplate P/N 30143

http://asp.vicorpower.com/CADPDF/9YRD8X.PDF

Module shield for Micro with slotted baseplate P/N 30141

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http://asp.vicorpower.com/CADPDF/NG6SIS.PDF

Apps. Eng. 800 927.9474 800 735.6200

Page 21

5. Current Sharing In Power Arrays

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

Design Guide & Applications Manual

Whenever power supplies or converters are operated in a parallel configuration — whether for higher output power, fault tolerance, or both — current sharing is an

mportant consideration. Most current-sharing schemes

i employed with power converters involve either artificially

ncreasing the output impedance of the converter module

i or actually sensing each output current, forcing all of the currents to be equal by feedback control. In a synchronous current-sharing scheme, however, there is no need for having a current-sensing or current-measuring device on each module, nor is there a need to artificially increase the output impedance, which compromises load regulation.

WHY IS CURRENT SHARING IMPORTANT

Most paralleled power components — transistors, rectifiers, power conversion modules, offline power supplies — will not inherently share the load. In the case of power converters, one or more of the converters will try to assume a disproportionate or excessive fraction of the load unless forced current-share control is designed into the system. One converter — typically the one with the highest output voltage — may deliver current up to its current limit setting, which is beyond its rated maximum. Then the voltage will drop to the point where another converter in the array — the one with the next highest voltage — will begin to deliver current. All of the converters in an array may deliver some current, but the load will be shared unequally. Built-in current limiting may cause all or most converters to deliver current, but the loading will remain unbalanced, and potentially cause damage to the converters.

Consider the situation when one module in a two-module array is providing all of the load. If it fails, the load on the second module must go from no load to full load, during which time the output voltage is likely to droop temporarily. This could result in system problems, including shutdown or reset. If both modules were sharing the load and one failed, however, the surviving module would experience a much less severe transient (one half to full load), and the output voltage would be likely to experience no more than a slight momentary droop. The dynamic response characteristic of all forward converters, resonant or pulsewidth modulated, is degraded when the load is stepped from zero (no load) where the output inductor current is discontinuous.

In the same two-module array example, the module carrying all of the load is also generating all of the heat, resulting in a much lower mean time between failure (MTBF) for that module. An often-quoted rule of thumb says that for each 10°C increase in operating temperature, average component life is cut in half. In a current-sharing system, all of the converters or supplies

run at a lower temperature than some modules would in a system without current sharing. As a result, all of the modules age equally.

Current sharing, then, is important because it improves system performance; it minimizes transient / dynamic response and thermal problems and improves reliability. It is an essential ingredient in most systems that use multiple power supplies or converters for higher output power or for fault tolerance.

CURRENT-SHARING IN POWER EXPANSION ARRAYS

When parallel supplies or converters are used to increase power, current sharing is achieved by a number of approaches. One scheme simply adds resistance in series with the load. A more practical variant of that is the “droop-share” method, which actively causes the output voltage to drop in response to increasing load. The two most commonly used approaches to paralleling converters for power expansion are the driver/booster or master/ slave arrays and analog current-share control. They appear to be similar, but the implementation of each is quite different. Driver/booster arrays usually contain one intelligent module or driver, and one or more power-trainonly modules or boosters. Analog current-share control involves paralleling two or more identical modules, each containing intelligence.

Droop Share. The droop-share method, shown in Figure 5–1, increases the output impedance to force the currents to be equal. It is accomplished by an error signal, which is interjected into the control loop of the converter causing the output voltage to operate as a function of load current. As load current increases, output voltage decreases. All of the modules will have approximately the same amount of current because they are all being summed into one node. If one supply is delivering more current than another supply, its output voltage will be forced down a little so that it will be delivering equal current for an equal voltage out of that summing node. Figure 5–1 illustrates a simple implementation of this scheme where the voltage dropped across the ORing diode, being proportional to current, is used to adjust the output voltage of the associated converter.

Droop share has advantages and disadvantages. One of the advantages is that it can work with any topology. It is also fairly simple and inexpensive to implement. A major drawback, though, is that it requires that the current be sensed. A current-sensing device is needed in each of the converters or power supplies. In addition, a small penalty is paid in load regulation, although in many applications this is not an issue.

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Page 22

Design Guide & Applications Manual

Return

+OUT

–S

–OUT

–IN

+IN

+OUT

–S

–OUT

–IN

+IN

DC-DC Converter

Maxi or Mini

+IN

– IN

+OUT

DC-DC Converter

Maxi or Mini

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

5. Current Sharing In Power Arrays

In general, it is not recommended to mix and match converters, especially those with incompatible current-sharing schemes. The droop-share method, however, is more

orgiving in this regard than with any of the other

f methods. Current sharing can be achieved using arrays

onstructed from different converter models or even from

c different suppliers with a little external circuitry.

Driver/ Booster Arrays. Most Vicor converters can employ the driver/booster array for increased power. (Figure 5–2) Driver/booster arrays usually contain one intelligent module or driver, and one or more power-trainonly modules or boosters. The driver is used to set and control output voltage, while booster modules are used to increase output power to meet system requirements.

Driver/booster arrays of quasi-resonant converters with identical power trains inherently current share because the per-pulse energy of each converter is the same. If the inputs and outputs are tied together and the units have the same clock frequency, all modules will deliver the same current (within component tolerances). The single intelligent module in the array determines the transient response, which does not change as modules are added. Booster modules require only one connection between units when their outputs are connected; no trimming, adjustments, or external components are required to achieve load sharing. The load sharing is dynamic and usually guaranteed to be within five percent.

It is important to remember that when using boosters, the input voltage, output voltage, and output power of the boosters must be the same as the driver.

The advantages of driver/booster arrays are that they have only a single control loop so there are no loop-withina-loop stability issues, and they have excellent transient response. However, this arrangement is not fault tolerant. If the driver module fails, the array will fail to maintain its output voltage.

Analog Current-Share Control. Analog current-share control, typical of PWM type converters, involves paralleling two or more identical modules, each containing intelligence. The circuit actively adjusts the output voltage of each supply so that the multiple supplies deliver equal currents. This method, however, has a number of disadvantages. Each converter in the array has its own voltage regulation loop, and each requires a current sensing device and current control loop.

Analog current-share control supports a level of redundancy, but it is susceptible to single-point failures within the current-share bus that can, at best, defeat current sharing, and, at worst, destroy every module in the array. The major reason for this is the single-wire galvanic connection between modules.

Figure 5–1 — The droop-share method artificially increases the output impedance to force the currents to be equal.

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5. Current Sharing In Power Arrays

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

Design Guide & Applications Manual

CURRENT SHARING IN FAULT TOLERANT ARRAYS

Current sharing is an essential element in fault-tolerant arrays, and regardless of the approach, there is an inherent additional cost incurred by the addition of at least one redundant converter or supply.

Most applications today that require fault tolerance or redundancy also require Hot-Swap capability to ensure continuous system operation. Hot swappable cards must be designed so that the operator cannot come in contact with dangerous potentials, currents or thermal hazards. It is also essential that when a module fails, the failure is detected and identified by an alarm or notice to provide service. A Hot-Swap system must ensure that during swap out there is minimal disturbance of the power bus. Specifically, the affected voltage bus must not drop enough to cause errors in the system, either on the input bus or the output bus.

N+1 Redundancy. A power supply failure can cripple an entire system, so a redundant converter or supply can be added to ensure that, in the event of a failure, the system will continue to operate. Adding an extra module (N+1) to a group of paralleled modules will significantly increase reliability with only a modest increase in cost.

How redundant converters are implemented is determined in part by the available space and cost requirements. Two 500 W Maxi modules, for example, could be used to provide a 1 kW output with an additional 500 W module for 2+1 redundancy a total of 1.5 kW in a volume of about 16.5 in3 (270 cm3). Four 200 W half-size modules might be used instead with a fifth 200 W module for 4+1 redundancy, a total of 1 kW and 14 in3(229 cm3). Although the second solution uses less space, it increases the accumulated failure rate because it employs more converters, more ORing diodes, more monitoring circuitry, and more assembly.

ORing diodes may be inserted in series with the +Output of each module in a N+1 array to provide output fault tolerance (Figure 5–1). They are important in a redundant power system to maintain fault isolation. Without them, a short-circuit failure in the output of one converter could bring down the entire array. As well, fusing the input of each converter prevents a converter input short from compromising the entire array.

ORing diodes, however, add losses to the power system, reducing overall efficiency (and, potentially, decreasing reliability). To ameliorate this negative effect on efficiency, ORing diodes should run hot, thereby reducing forward voltage drop and improving system efficiency. Reverse leakage current will be an issue only if the output of a converter shorts and the diode is reverse biased. This is an important consideration with regard to operating temperature.

Current sharing, required to ensure system reliability, can be implemented by a multiplicity of methods. Figure 5–1, shown earlier as an example of the droop-share method,

s also an example of N+1 redundancy using ORing diodes.

Synchronous Current Sharing. Synchronous current sharing is available with Maxi, Mini, Micro converters — converters that use the zero-current-switching and zerovoltage-switching topology. Each module has the capability to assume control of the array, that is, they constitute a democratic array. The module that assumes command transmits a pulse on the parallel bus to which all other modules on the bus synchronize.

The converters use this pulse as a current-sharing signal for power expansion and fault-tolerant applications. The pulsed signal on the parallel bus simplifies current-sharing control by synchronizing the high-frequency switching of each converter. The parallel pin is a bi-directional port on each module used to transmit and receive information between modules. If the lead module relinquishes control, another module in the array will transparently take command with little or no perturbation of the output bus. A pulsed signal gives designers the option to use capacitors (Figure 5–2) or transformers between parallel pins, providing DC-blocked coupling. Such coupling prevents certain failure modes internal to a single module from affecting the other modules in the array, thus providing an increased level of fault tolerance.

Use of a current-share bus transformer (Figure 5–3) enables arrays of Maxi, Mini, Micro converters to current share when they are widely separated or operated from independent sources. Since the current-share signal is a pulsed signal, it can be transformer coupled. Transformer coupling this pulsed signal provides a high level of common-mode noise immunity while maintaining SELV isolation from the primary source. This is especially useful when board-to-board load sharing is required in redundant applications.

Synchronous current sharing eliminates the need for current-sensing or current-measuring devices on each module, and load regulation is not compromised. Additional advantages of the synchronous current sharing architecture includes excellent transient response, “no loop within a loop” control problems, and, a high degree of immunity from system noise. The availability of synchronous current sharing in democratically controlled arrays offers power architects new opportunities to achieve simple, non-dissipative current-share control. It provides options that simplify current sharing and eliminates the tradeoffs — such as the need to sense the current from each individual module and adjust each control voltage — as is the case with other current-sharing methods.

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Design Guide & Applications Manual

Ground

Plane

OUT

–

–OUT

–

+IN

OUT

–S

–OUT

–

+IN

Return

DC-DC Converter

Parallel

Bus

-V

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

5. Current Sharing In Power Arrays

The synchronous current-sharing method applies to quasi-resonant, frequency-modulated converters with the necessary intelligence, such as the Vicor Maxi, Mini, Micro

amily of high-density DC-DC converters, where the energy

F per pulse is fixed.

Finally, no matter what method is used, current sharing reduces thermal problems, improves transient response, and helps extend the lifetimes of all modules in an

rray. Nevertheless, all current-sharing schemes require

a careful attention to electrical and mechanical design to

perate effectively.

Figure 5–2 — Synchronous power architecture simplifies current sharing control and enhances fault tolerance.

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5. Current Sharing In Power Arrays

Parallel Bus

-V

+OUT

–S

–OUT

–IN

+OUT

–S

–OUT

–IN

+IN

Return

OUT

-V

DC-DC Converter

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

Design Guide & Applications Manual

Figure 5–3 — Transformer-coupled interface provides load sharing and SELV isolation from the primary source.

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Design Guide & Applications Manual

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

6. Thermal Performance Information

Simplified thermal management is one of the benefits of using Vicor converters. High operating efficiency minimizes heat loss, and the low-profile package features an easily

ccessible, electrically isolated thermal interface surface.

Proper thermal management pays dividends in terms of improved converter and system MTBFs, smaller size, and lower product life-cycle costs. The following pages provide guidelines for achieving effective thermal management of

Consideration should be given to the module baseplate temperature during operation. The maximum baseplate temperature specification for Maxi, Mini, and Micro is

00°C.

Enhanced module cooling can be achieved with free or forced convection by using the appropriate heat sink. The available Vicor heat sinks and thermal interface options are available on the Vicor website.

Vicor converters.

The relevant nomenclature for the tabulated thermal information supplied in this section for the Maxi, Mini, and Micro modules is defined as follows:

Tb = baseplate temperature

Ta = ambient temperature

Pout = module output power

Pin= module input power

η = module efficiency = Pout / Pin

Pdiss = module power dissipation = Pin – Pout = (1/η – 1) • Pout

Supplied thermal resistance values:

θbs = baseplate-to-heatsink thermal resistance

θba = baseplate-to-ambient thermal resistance

Basis of output power versus ambient temperature derating curves:

(Ta)max = (Tb)max – θba • Pdiss = (Tb)max – θba • (1/η – 1) • Pout

Additional Thermal Data

The following pages contain temperature derating curves.

For additional thermal data, see the following link:

http://asp.vicorpower.com/calculators/calculators.asp?calc=5

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6. Thermal Performance Information

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12 - 48V Maxi Thermal Performance Curves - No Heat Sink

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12 - 48V Maxi Thermal Performance Curves - .4" Heat Sink

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12 - 48V Maxi Thermal Performance Curves - .9" Heat Sink

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Design Guide & Applications Manual

For Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

THERMAL PERFORMANCE CURVES (Maxi)

Table Usage: The forced convection thermal impedance data shown in the tables on the next three pages assumes airflow through the heat sink fins. Actual airflow through the fins should be verified. For purposes of heat sink calculation, assume efficiencies listed on Maxi data sheets. Use as a design guide only. Verify final design by actual temperature measurement.

Maxi

bs = 0.07°C/W Baseplate 0.9'' Longitudinal Fins 0.9'' Transverse Fins 0.4'' Longitudinal Fins 0.4'' Transverse Fins

ba (Baseplate-to-Ambient Thermal Resistance Values) vs. Airflow

Free Air 4.98 2.89 2.24 3.72 3.49 200 LFM 3.23 1.30 1.02 2.14 1.53 400 LFM 2.17 0.90 0.72 1.48 1.08 600 LFM 1.73 0.72 0.60 1.10 0.87 800 LFM 1.46 0.59 0.51 0.86 0.70

1,000 LFM 1.27 0.51 0.44 0.71 0.60 1,200 LFM 1.14 0.46 0.41 0.61 0.55

Maxi Output Power vs. Ambient Temperature Derating Curves

Baseplate (No Heat Sink) 0.4'' (10,1 mm) Heat Sink 0.9'' (22,8 mm) Heat Sink

2 V

3.3 V

5 V

12 – 54 V

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Free Air 200 LFM 400 LFM 600 LFM 800 LFM 1000 LFM 1200 LFM

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Design Guide & Applications Manual

2V Mini Thermal Performance Curves - No Heat Sink

100

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100

mbient Temperature (deg C)

Output Power (Watts)

2V Mini Thermal Performance Curves - .4" Heat Sink

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100

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2V Mini Thermal Performance Curves - .9" Heat Sink

100

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Output Power (Watts)

.3V Mini Thermal Performance Curves - No Heat Sink

120

140

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3.3V Mini Thermal Performance Curves - .4" Heat Sink

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.3V Mini Thermal Performance Curves - .9" Heat Sink

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5V Mini Thermal Performance Curves - No Heat Sink

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5V Mini Thermal Performance Curves - .4" Heat Sink

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12 - 48V Mini Thermal Performance Curves - No Heat Sink

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12 - 48V Mini Thermal Performance Curves - .9" Heat Sink

100

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or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

6. Thermal Performance Information

THERMAL PERFORMANCE CURVES (Mini)

Table Usage: The forced convection thermal impedance data shown in the tables on the next three pages assumes airflow through the heat sink fins. Actual airflow through the fins should be verified. For purposes of heat sink calculation, assume efficiencies listed on Mini data sheets. Use as a design guide only. Verify final design by actual temperature measurement.

Mini

ba (Baseplate-to-Ambient Thermal Resistance Values) vs. Airflow

bs = 0.14°C/W Baseplate 0.9'' Longitudinal Fins 0.9'' Transverse Fins 0.4'' Longitudinal Fins 0.4'' Transverse Fins

Free Air 7.94 4.10 3.93 6.28 6.34 200 LFM 4.50 1.72 1.93 2.81 3.00 400 LFM 3.20 1.26 1.38 1.98 2.09 600 LFM 2.52 1.02 1.06 1.55 1.59 800 LFM 2.15 0.86 0.89 1.24 1.31

1,000 LFM 1.89 0.75 0.77 1.05 1.11 1,200 LFM 1.69 0.68 0.70 0.94 0.99

Mini Output Power vs. Ambient Temperature Derating Curves

Baseplate (No Heat Sink) 0.4'' (10,1 mm) Heat Sink 0.9'' (22,8 mm) Heat Sink

2 V

3.3 V

5 V

12 – 54 V

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Page 27 of 88

Free Air 200 LFM 400 LFM 600 LFM 800 LFM 1000 LFM 1200 LFM

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6. Thermal Performance Information

2V Micro Thermal Performance Curves - No Heat Sink

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100

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2V Micro Thermal Performance Curves - .4" Heat Sink

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2V Micro Thermal Performance Curves - .9" Heat Sink

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3.3V Micro Thermal Performance Curves - No Heat Sink

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3.3V Micro Thermal Performance Curves - .4" Heat Sink

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.3V Micro Thermal Performance Curves - .9 Heat Sink

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5V Micro Thermal Performance Curves - No Heat Sink

100

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V Micro Thermal Performance Curves - .4" Heat Sink

100

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or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

Design Guide & Applications Manual

THERMAL PERFORMANCE CURVES (Micro)

Table Usage: The forced convection thermal impedance data shown in the tables on the next three pages assumes airflow through the heat sink fins. Actual airflow through the fins should be verified. For purposes of heat sink calculation, assume efficiencies listed on Micro data sheets. Use as a design guide only. Verify final design by actual temperature measurement.

Micro

bs = 0.21°C/W Baseplate 0.9'' Longitudinal Fins 0.9'' Transverse Fins 0.4'' Longitudinal Fins 0.4'' Transverse Fins

ba (Baseplate-to-Ambient Thermal Resistance Values) vs. Airflow

Free Air 10.90 5.37 5.04 7.77 7.76 200 LFM 6.90 2.51 2.31 3.87 3.58 400 LFM 4.78 1.79 1.68 2.68 2.52 600 LFM 3.74 1.42 1.31 2.13 2.01 800 LFM 3.15 1.20 1.10 1.78 1.67

1,000 LFM 2.79 1.06 0.97 1.48 1.45 1,200 LFM 2.49 0.93 0.88 1.32 1.29

Micro Output Power vs. Ambient Temperature Derating Curves

Baseplate (No Heat Sink) 0.4'' (10,1 mm) Heat Sink 0.9'' (22,8 mm) Heat Sink

2 V

3.3 V

5 V

12 – 54 V

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Free Air 200 LFM 400 LFM 600 LFM 800 LFM 1000 LFM 1200 LFM

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or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

Typical Examples — Thermal Equations (Maxi, Mini, Micro)

EXAMPLE 1

etermine the maximum output power for a Maxi module without a heat sink delivering 5 V in 400 LFM

D airflow at a maximum ambient temperature of 40ºC.

6. Thermal Performance Information

Maximum output power = (T

= 100ºC

= 40ºC

max

– Ta

)/[θba • (1/η – 1)]

For Maxi module without a heat sink @ 400 LFM, θba = 2.17ºC/W

For the 5 V Maxi module the typical value for η = 0.83

Maximum output power = (100 – 40) / [2.17 (1/0.83 – 1)] ~135 W

Or, the same answer could be obtained by using the output power versus ambient temperature derating curves for the Maxi modules.

For the case with no heat sink the baseplate chart for the 5 V module would be used. At a 40ºC ambient and 400 LFM airflow this chart indicates a maximum output power of approximately 135 W.

For full output power of 400 W the required thermal resistance is;

θba = (100 – 40) / [400 (1/0.83 – 1)] = 0.73ºC/W

What size heat sink would be necessary to operate at full output power (400 W) under the same conditions?

From the θba versus airflow charts for the Maxi, the thermal resistance at 400 LFM airflow requires the use of a 0.9"(22,8 mm) transverse fin heat sink.

EXAMPLE 2

Determine the maximum ambient for a Mini module with a 0.9” (22,8 mm) heat sink in 400 LFM of airflow delivering 200 W at 5 V.

From the output power versus ambient temperature chart for the 5 Vout Mini with a 0.9’’ (22,8 mm) heat sink, the 200 W at 400 LFM data point results in a Ta

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Page 29 of 88

5 V Mini with

0.9” (22,8 mm) heat sink

of approximately 48ºC.

max

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6. Thermal Performance Information

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

Design Guide & Applications Manual

THERMAL MANAGEMENT ACCESSORIES (All parts are RoHS compliant unless otherwise noted)

axi Heat Sinks Mini Heat Sinks Micro Heat Sinks

Threaded Through Hole Threaded Through Hole Threaded Through Hole

0.4" (10,1 mm) Fin 0.4" (10,1 mm) Fin 0.4" (10,1 mm) Fin 0.4" (10,1 mm) Fin 0.4" (10,1 mm) Fin 0.4" (10,1 mm) Fin P/N 30482 P/N 30718 P/N 32188 P/N 30195 P/N 32174 P/N 30719

0.9" (22,8 mm) Fin 0.9" (22,8 mm) Fin 0.9" (22,8 mm) Fin 0.9" (22,8 mm) Fin 0.9" (22,8 mm) Fin 0.9" (22,8 mm) Fin P/N 30188 P/N 30181 P/N 30189 P/N 30182 P/N 30190 P/N 30183

0.4" (10,1 mm) Fin 0.4" (10,1 mm) Fin 0.4" (10,1 mm) Fin 0.4" (10,1 mm) Fin 0.4" (10,1 mm) Fin 0.4" (10,1 mm) Fin P/N 30778 P/N 30720 P/N 30184 P/N 30721 P/N 32173 P/N 30722

Transverse Fins Longitudinal Fins

0.9" (22,8 mm) Fin 0.9" (22,8 mm) Fin 0.9" (22,8 mm) Fin 0.9" (22,8 mm) Fin 0.9" (22,8 mm) Fin 0.9" (22,8 mm) Fin P/N 30196 P/N 30723 P/N 30269 P/N 30724 P/N 30270 P/N 30725

Low-profile Side-fin Heat Sinks

Height only 0.125" (3,17 mm) above module baseplate*

0.55" (13,97 mm) 0.55" (13,97 mm) 0.55" (13,97 mm) Side Fins Side Fins Side Fins

P/N 30096 P/N 32190 P/N 30095

See the specific products on the Vicor website for more information.

Standoffs and Screws

Bulk and single-module kits compatible

with all standard mounting configurations.

Not compatible with standoff kits.

ThermMate Thermal Pads

For use with Vicor modules, ThermMate thermal pads are a “dry” alternative to

20263

20265

20264

* For thermal curves of low-profile side-fin heat sinks and on-line capability for thermal curve calculations, see the following link:

http://asp.vicorpower.com/calculators/calculators.asp?calc=5

thermal compound and are pre-cut to the outline dimensions of the module.

THERMAL PAD PART NUMBER THICKNESS

Maxi (10 pc. pkg.) 20263 0.007" (0,177 mm) Mini (10 pc. pkg.) 20264 0.007" (0,177 mm) Micro (10 pc. pkg.) 20265 0.007" (0,177 mm)

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Design Guide & Applications Manual

Microcontroller

PTC

Thermistor

+OUT

–OUT

Strap

BOK

Strap

400 300 200 100

90–132 V

AC Line

Output

Bus

(Vdc)

Strap

PTC

Thermistor

Bypass

Converter

Enable

Bus OK

~150 ms

Power

Power Down

4.1

1.1

2.1

3.1

5.1

2.2

1.2

~150 ms

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

7. Autoranging Rectifier Module (ARM)

The Autoranging Rectifier Module (ARM) provides an effective solution for the AC front end of a power supply designed with Vicor DC-DC converters. This high-perform-

nce power system building block satisfies a broad

a spectrum of requirements and agency standards.

The ARM contains all of the power switching and control circuitry necessary for autoranging rectification, inrush current limiting, and overvoltage protection. This module also provides converter enable and status functions for orderly power up / down control or sequencing. To complete the AC front-end configuration, the user needs only to add hold-up capacitors and a suitable input filter with transient protection.

FUNCTIONAL DESCRIPTION (Figure 7–1)

Initial Conditions. The switch that bypasses the inrush limiting PTC (positive temperature coefficient) thermistor is open when power is applied, as is the switch that engages the strap for voltage doubling. In addition, the downstream DC-DC modules are disabled via the Enable (EN) line, and Bus OK (BOK) is high.

POWER-DOWN SEQUENCE (Figure 7–2)

When input power is turned off or fails, the following sequence occurs as the bus voltage decays:

1.2 Bus OK is de-asserted when the bus voltage falls elow 205 Vdc (typical).

2.2 The converters are disabled when the bus voltage falls

below 200 Vdc. If power is reapplied after the converters are disabled, the entire power-up sequence is repeated. If a momentary power interruption occurs and power is re-established before the bus reaches the disable threshold, the power-up sequence is not repeated.

POWER-UP SEQUENCE (Figure 7–2)

1.1 Upon application of input power, the output bus capacitors begin to charge. The thermistor limits the charge current, and the exponential time constant is determined by the hold-up capacitor value and the

Figure 7–1 — Functional block diagram

thermistor cold resistance. The slope (dv/dt) of the capacitor voltage approaches zero as the capacitors become charged to the peak of the AC line voltage.

2.1 If the bus voltage is less than 200 V as the slope nears zero, the voltage doubler is activated, and the bus voltage climbs exponentially to twice the peak line voltage. If the bus voltage is greater than 200 V, the doubler is not activated.

3.1 If the bus voltage is greater than 235 V as the slope approaches zero, the inrush limiting thermistor is bypassed. Below 235 V, the thermistor is not bypassed.

4.1 The converters are enabled ~150 milliseconds after the thermistor bypass switch is closed.

5.1 Bus OK is asserted after an additional ~150 millisecond

Figure 7–2 —Timing diagram: power up / down sequence

delay to allow the converter outputs to settle within specification.

Maxi, Mini, Micro Design Guide Rev 4.9 vicorpower.com

Page 31 of 88

Apps. Eng. 800 927.9474 800 735.6200

Page 33

7. Autoranging Rectifier Module (ARM)

+IN

PC (GATE IN)

–IN

+IN

PC (GATE IN)

–IN

BOK

–V

Vicor DC-DC

Converter

VI-ARM

R1R2C1

Vicor DC-DC

Converter

To additional modules

C7*

C8*

Filter

C10

C11

Not used with VI-260/VI-J60

Part Description Vicor Part Number

C1,2 Holdup capacitors

C3–6 4700pF (Y2 type) 01000

R1,2 150 k, 0.5 W 00127-1503

V1,2 220 V MOV 30234-220

F1,2 Use reccommended fusing for specific DC-DC Converters

D1,2 Diode 00670

C7,8* Film Cap., 0.61 µF 34610

Z1 MOV (270 V) 30076

D3,D4 1N5817 26108

C10,C11 0.001 µF

R3, R4** 250 Ω

F3 ABC-10 A VI-ARM-_1 ABC-10 A VI-ARMB-_2

Sizing PCB traces:

All traces shown in bold carry significant current and should be sized accordingly.

*Required if C1 & C2 are located more than 6 inches (15 cm) from output of VI-ARM. **

Not used with VI-260/VI-J60

OFF-LINE POWER SUPPLY CONFIGURATION

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

Design Guide & Applications Manual

The ARM maintains the DC output bus voltage between 200 and 375 Vdc over the entire universal input range, this being compatible with the Maxi, Mini, Micro 300 V input converters as well as VI-260 family and VI-J60 family DC-DC converters. The ARM automatically switches to the proper rectification mode (doubled or undoubled) depending on the input voltage, eliminating the possibility of damage due to improper line connection. The VI-ARM-x1 is rated at 500 W in the low range (90 –132 Vac input), and 750 W in the high range (180 – 264 Vac input). The VI-ARMB–x2 is rated for 750 W and 1,500 W for the low and high input ranges respectively. Either of these modules can serve as the AC front end for any number and combination of compatible converters as long as the maximum power rating is not exceeded. See VI-ARMB derating curves (Figures 1 and 2) on VI-ARM data sheet.

Strap (ST) Pin. In addition to input and output power pin connections, it is necessary to connect the Strap pin to the junction of the series hold-up capacitors (C1, C2, Figure 7–3) for proper (autoranging) operation. Varistors across the capacitors provide input transient protection. The bleeder resistors (R1, R2, Figure 7–3) discharge the hold-up capacitors when power is switched off.

Enable (EN) Pin. (Figure 7–4) The Enable pin must be connected to the PC or GATE IN pin of all converter modules to disable the converters during power up. Otherwise, the converters would attempt to start while the hold-up

capacitors were being charged through an un-bypassed thermistor, preventing the bus voltage from reaching the thermistor bypass threshold, thus disabling the power supply. The Enable output (the drain of a N channel MOSFET) is internally pulled up to 15 V through a 150 kΩ resistor.

A signal diode should be placed close to and in series with the PC or GATE IN pin of each converter to eliminate the possibility of control interference between converters. The Enable pin switches to the high state (15 V) with respect to the negative output power pin to turn on the converters after the power-up inrush is over. The Enable function also provides input overvoltage protection for the converters by turning off the converters if the DC bus voltage exceeds 400 Vdc. The thermistor bypass switch opens if this condition occurs, placing the thermistor in series with the input voltage, which reduces the bus voltage to a safe level while limiting input current in case the varistors conduct. The thermistor bypass switch also opens if a fault or overload reduces the bus voltage to less than 180 Vdc.

CAUTION: There is no input to output isolation in the ARM, hence the –Out of the ARM and thus the –In of the downstream DC-DC converter(s) are at a high potential. If it is necessary to provide an external enable / disable function by controlling the DC-DC converter’s PC or GATE IN pin (referenced to the –In) of the converter an opto-isolator or isolated relay should be employed.

Figure 7–3 — Typical ARM application

Maxi, Mini, Micro Design Guide Rev 4.9 vicorpower.com

Page 32 of 88

Apps. Eng. 800 927.9474 800 735.6200

Page 34

Design Guide & Applications Manual

L2/N

GND

art Description Vicor Part Number

1 1.0 µF 02573

2, C3 4700pF (Y2 type) 03285

4 0.15µF 03269

1 10 A Max 05147

1, L2 27 µH 32012

3 2.2 mH 32006

1, R2 10 Ω

3 150 kΩ, 0.5 W

4 2.2 Ω

1 MOV 30076

L2/N

Part Description Vicor Part Number L

1,L4 1,000 µH 12 A / 6.5 M

Ω

31743 L2, L3 22 µH 33206 C1 0.68 µF (X type) 02573 C

2,C3,C4,C5 4700pF (Y2 type) 03285 C6 0.22 µF (X type) 04068 R1 390 k

Ω 1/2 W R2 10 Ω 1/2 W F

1 15 A Max

Z1 MOV 30076

+IN

(GATE IN)

–

Vicor

C-DC

Converter

Micro-

controller

15 Vdc

To additional modules

Not used with VI-260/VI-J60

–IN

BOK

–

Vicor

DC-DC

onverter

Micro-

controller

15 V dc

+5 V dc

Secondary referenced

To additional modules

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

7. Autoranging Rectifier Module (ARM)

Figure 7–4 — Enable (EN) function

Figure 7–6a — Recommended filter design; Low power filter

connection for VI-ARM-x1

Bus OK (BOK) Pin. (Figure 7–5) The Bus OK pin is intended to provide early-warning power fail information and is also referenced to the negative output pin.

CAUTION: There is no input-to-output isolation in the ARM. It is necessary to monitor Bus OK via an optocoupler if it is to be used on the secondary (output) side of the converters. A line-isolation

Figure 7–5 — Bus OK (BOK) isolated power status indicator

Figure 7–6b — Recommended filter design; High power filter

connection for VI-ARMB-x2

specified duration, i.e., the converters must hold up or ride through such an event while maintaining undisturbed output voltage regulation. Similarly, many of these same systems require notification of an impending power failure to allow time to perform an orderly shutdown.

The energy stored on a capacitor, which has been charged to voltage V, is:

transformer should be used when performing scope measurements. Scope probes should never be applied

ε = 1/2(CV

) (1)

simultaneously to the input and output as this will damage the module.

Filter. Two input filter recommendations are shown for low-power VI-ARM-x1 and high-power VI-ARMB-x2.

where: ε = stored energy

C = capacitance

V = voltage across the capacitor

(Figures 7–6a and 7–6b)

Energy is given up by the capacitors as they are discharged

Both filter configurations provide sufficient common-mode and differential-mode insertion loss in the frequency range

by the converters. The energy expended (the power-time product) is:

between 100 kHz and 30 MHz to comply with the Class B conducted emissions limit.

Hold-up Capacitors. Hold-up capacitor values should be determined according to output bus voltage ripple, power fail hold-up time, and ride-through time. (Figure 7–7) Many applications require the power supply to maintain output regulation during a momentary power failure of

Maxi, Mini, Micro Design Guide Rev 4.9 vicorpower.com

Page 33 of 88

Apps. Eng. 800 927.9474 800 735.6200

where: P = operating power

ε = P∆t = C(V1

∆t = discharge interval

V1 = capacitor voltage at the beginning of ∆t

V2 = capacitor voltage at the end of ∆t

– V22) / 2 (2)

Page 35

7. Autoranging Rectifier Module (ARM)

Operating Power (W)

P-P Ripple Voltage (Vac)

150012501000750500250

2,200 µF1,600 µF1,300 µF

1,100 µF

820 µF

680 µF

(VI-ARM-x1)

(VI-ARMB-x2)

Output Voltage

Ripple Rejection (dB)

50301552

Operating Power (W)

Ride –Through Time (ms)

100

90 Vac 115 Vac

150012501000750500250

Total

capacitance

820 µF

205 V 190 V

Power

Fail

Power Fail

Warning

Bus OK

Converter

Shut down

Hold-up Time

254 V

Ride-Through Time

Ripple (V p-p)

π – θ θ

Operating Power (W)

Power Fail Warning Time (ms)

50012501000750500250

2,200 µF1,600 µF1,300 µF

1,100 µF

820 µF

680 µF

(

VI-ARM-x1)

(VI-ARMB-x2)

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

Figure 7–7 — General timing diagram of bus voltage following interruption of the AC mains

Design Guide & Applications Manual

Figure 7–8 — Power fail warning time vs. operating power and

Figure 7–9 — Ride-through time vs. operating power

total bus capacitance, series combination of C1, C2 (Figure 7–3)

Figure 7–10 — Ripple voltage vs. operating power and bus capacitance, series combination of C1, C2 (Figure 7–3)

Maxi, Mini, Micro Design Guide Rev 4.9 vicorpower.com

Page 34 of 88

Apps. Eng. 800 927.9474 800 735.6200

Figure 7–11 — Converter ripple rejection vs. output voltage (Typical)

Page 36

Design Guide & Applications Manual

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

7. Autoranging Rectifier Module (ARM)

Rearranging equation 2 to solve for the required capacitance:

C = 2P∆t / (V12–V22) (3)

The power fail warning time (∆t) is defined as the interval between (BOK) and converter shutdown (EN) as illustrated in Figure 7–7. The Bus OK and Enable thresholds are 205 V and 190 V, respectively. A simplified relationship between power fail warning time, operating power, and bus capacitance is obtained by inserting these constants:

C = 2P∆t / (2052– 1902)

C = 2P∆t / (5,925)

It should be noted that the series combination (C1, C2, Figure 7–3) requires each capacitor to be twice the calculated value, but the required voltage rating is reduced to 200 V.

Allowable ripple voltage on the bus (or ripple current in the capacitors) may define the capacitance requirement. Consideration should also be given to converter ripple rejection and resulting output ripple voltage.

For example, a converter whose output is 15 V and nominal input is 300 V will provide typically 56 dB ripple rejection, i.e., 10 V p-p of input ripple will produce 15 mV p-p of output ripple. (Figure 7–11) Equation 3 is again used to determine the required capacitance. In this case, V1 and V2 are the instantaneous values of bus voltage at the peaks and valleys (Figure 7–7) of the ripple, respectively. The capacitors must hold up the bus voltage for the time interval (∆t) between peaks of the rectified line as given by:

∆t = (π– θ) / 2πf (4)

where: f = line frequency

θ = rectifier conduction angle

(Figure 7–7)

The approximate operating ripple current (rms) is given by:

Irms = 2P / Vac (6)

where: P = operating power level

Vac = operating line voltage

Calculated values of bus capacitance for various hold-up time, ride-through time, and ripple voltage requirements are given as a function of operating power level in Figures 7–8, 7–9, and 7–10, respectively.

EXAMPLE

In this example, the output required at the point of load is 12 Vdc at 320 W. Therefore, the output power from the ARM would be 375 W (assuming a converter efficiency of 85%). The desired hold-up time is at least 9 ms over an input range of 90 to 264 Vac.

Determining Required Capacitance for Power Fail Warning. Figure 7–8 is used to determine capacitance

for a given power fail warning time and power level, and shows that the total bus capacitance must be at least 820 µF. Since two capacitors are configured in series, each capacitor must be at least 1,640 µF.

NOTE

: The warning time is not dependent on line voltage. A hold-up capacitor calculator is available on the Vicor website, at

http://asp.vicorpower.com/calculators/calculators.as p?calc=4

Determining Ride-through Time. Figure 7–9 illustrates ride-through time as a function of line voltage and output power, and shows that at a nominal line of 115 Vac, ridethrough would be 68 ms. Ride-through time is a function of line voltage.

Determining Ripple Voltage on the Hold-up Capacitors. Figure 7–10 is used to determine ripple

voltage as a function of operating power and bus capacitance, and shows that the ripple voltage across the hold-up capacitors will be 12 Vac.

Determining the Ripple on the Output of the DC-DC

The approximate conduction angle is given by:

Converter. Figure 7–11 is used to determine the ripple rejection of the DC-DC converter and indicates a ripple

θ = Cos

-1

V2 / V1 (5)

rejection of approximately 60 dB for a 12 V output. If the ripple on the bus voltage is 12 Vac and the ripple rejection of the converter is 60 dB, the output ripple of the converter due to ripple on its input (primarily 120 Hz)

Another consideration in hold-up capacitor selection is

will be 12 mV p-p.

their ripple current rating. The capacitors’ rating must be higher than the maximum operating ripple current.

Maxi, Mini, Micro Design Guide Rev 4.9 vicorpower.com

Page 35 of 88

Apps. Eng. 800 927.9474 800 735.6200

Page 37

8. Filter / Autoranging Rectifier Module (FARM)

Microcontroller

PTC

Thermistor

+OUT

–OUT

Strap

BOK

Strap

EMI

ilter

EMI GRD

400 300 200 100

90–132 V

AC Line

Output

Bus

(Vdc)

Strap

PTC

Thermistor

Bypass

Converter

Enable

Bus OK

~150 ms

Power

Down

4.1

1.1

2.1

3.1

5.1

2.2

1.2

~150 ms

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

Design Guide & Applications Manual

The Filter / Autoranging Rectifier Module (FARM) provides an effective solution for the AC front end of a power supply built with Vicor DC-DC converters. This high-

erformance power-system building block satisfies a

p broad spectrum of requirements and agency standards.

In addition to providing transient / surge immunity and EMI filtering, the FARM contains all of the power switching and control circuitry necessary for autoranging rectification, inrush current limiting, and overvoltage protection. This module also provides converter enable and status functions for orderly power up / down control or sequencing. To complete the AC front-end configuration, the user only needs to add hold-up capacitors, and a few discrete components.

FUNCTIONAL DESCRIPTION (Figure 8–1)

Initial Condition.The switch that bypasses the inrush limiting PTC (positive temperature coefficient) thermistor is open when power is applied, as is the switch that engages the strap for voltage doubling. In addition, the converters are disabled via the Enable (EN) line, and Bus OK (BOK) is high.

POWER-DOWN SEQUENCE (Figure 8–2)

When input power is turned off or fails, the following sequence occurs as the bus voltage decays:

1.2 Bus OK is de-asserted when the bus voltage falls elow 205 Vdc (Typical).

2.2 The converters are disabled when the bus voltage

falls below 190 Vdc. If power is reapplied after the converters are disabled, the entire power-up sequence is repeated. If a momentary power interruption occurs and power is re-established before the bus reaches the disable threshold, the power-up sequence is not repeated, i.e., the power supply “rides through” the momentary interruption.

POWER-UP SEQUENCE (Figure 8–2)

1.1 Upon application of input power, the output bus capacitors begin to charge. The thermistor limits the charge current, and the exponential time constant is determined by the hold-up capacitor

Figure 8–1 — Functional block diagram: FARM

value and the thermistor cold resistance. The slope (dv/dt) of the capacitor voltage versus time approaches zero as the capacitors become charged to the peak of the AC line voltage. If the bus voltage is less than 200 V as the slope nears zero, the voltage doubler is activated, and the bus voltage climbs exponentially to twice the peak line voltage.

2.1 If the bus voltage is greater than 200 V, the doubler is not activated.

3.1 If the bus voltage is greater than 235 V as the slope approaches zero, the inrush limiting thermistor is bypassed. Below 235 V, it is not bypassed.

4.1 The converters are enabled ~150 ms after the

Figure 8–2 — Timing diagram: power up/down sequence

thermistor bypass switch is closed.

5.1 Bus OK is asserted after an additional ~150 ms delay to allow the converter outputs to settle within specification.

Maxi, Mini, Micro Design Guide Rev 4.9 vicorpower.com

Page 36 of 88

Apps. Eng. 800 927.9474 800 735.6200

Page 38

Design Guide & Applications Manual

+IN

PC (GATE IN)

–IN

+IN

PC (GATE IN)

–IN

Vicor DC-DC

Converter

R1R2C1

Vicor DC-DC

Converter

To additional modules

C7**

C8**

FARM

Filter/Autoranging

Rectifier Module

EMI GND

N/C

BOK

–

C11

C10

Vicor Part Description Part Number

C1,2

Hold-up capacitors C3-C6 4,700 pF (Y2 type) 01000 C7,8** Film Cap., 0.61 µF 34610 C9 0.47 µF 03047 C10,C11 0.001 µF D1, 2 Diode 00670 D3, 4 1N5817 26108 F1, F2 Use recommended fusing for specific DC-DC Converters R1, 2 150 KΩ, 0.5 W R3, 4*** 250 Ω V1,2 220 V MOV 30234-220 Z1 MOV 270 30076

Sizing PCB traces:

All traces shown in bold carry significant current and should be sized accordingly.

N/ST/L 10 A rms at 90 Vac and 500 W +/– In 4 A DC at 190 Vdc and 750 W

FARM2-xxx N/ST/L 20 A rms at 90 Vac and 750 W +/– In 8 A DC at 190 Vdc and 1000 W

* See Agency Approvals on FARM data sheet.

**Required if C1 & C2 are located more than

3 in (75 mm) from output of the FARM. ***Not used with VI-260/VI-J60

Not used with VI-260/VI-J60

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

OFF-LINE POWER SUPPLY CONFIGURATION

8. Filter / Autoranging Rectifier Module (FARM)

The FARM maintains the DC output bus voltage between 250 and 370 Vdc over the entire input-voltage range, which is compatible with the Maxi, Mini, Micro 300 V input converters as well as VI-260 family and VI-J60 family DC-DC converters. The FARM automatically switches to the proper bridge or doubler mode depending on the input voltage, eliminating the possibility of damage due to improper line connection. The FARM1xxx is rated at 500 W in the low range (90 – 132 Vac input), and 750 W in the high range (180 – 264 Vac input). The FARM2xxx is rated for 750 W and 1,000 W for the low and high input ranges respectively. Either of these modules can serve as the AC front end for any number and combination of compatible converters as long as the maximum power rating is not exceeded.

Strap (ST) Pin. In addition to input and output power pin connections, it is necessary to connect the Strap pin to the center junction of the series hold-up capacitors (C1, C2, Figure 8–3) for proper (autoranging) operation. Metal-oxide varistors, V1 and V2 provide capacitor protection. The bleeder resistors (R1, R2, Figure 8–3) discharge the hold-up capacitors when power is switched off. Capacitors C7 and C8 are recommended if the hold-up capacitors are located more than 3 inches (75 mm) from the FARM output pins.

Enable (EN) Pin. (Figure 8-4) The Enable pin must be connected to the PC or GATE IN pin of all converter modules to disable the converters during power up. Otherwise, the converters would attempt to start while

the hold-up capacitors were being charged through an un-bypassed current-limiting thermistor, preventing the bus voltage from reaching the thermistor bypass threshold, thus disabling the power supply. The Enable output (the drain of an N channel MOSFET) is internally pulled up to 15 V through a 150 kΩ resistor.

CAUTION: There is no input to output isolation in the FARM, hence the –Out of the FARM and thus the –In of the downstream DC-DC converter(s) are at a high potential. If it is necessary to provide an external enable / disable function by controlling the DC-DC converter’s PC or GATE IN pin (referenced to the –In) of the converter an opto-isolator or isolated relay should be employed.

Figure 8–3 — Offline power supply configuration

Maxi, Mini, Micro Design Guide Rev 4.9 vicorpower.com

Page 37 of 88

Apps. Eng. 800 927.9474 800 735.6200

Page 39

8. Filter / Autoranging Rectifier Module (FARM)

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

Design Guide & Applications Manual

Bus OK (BOK) Pin. (Figure 8–5) The Bus OK pin is intended to provide early-warning power-fail information and is also referenced to the negative output pin.

CAUTION: There is no input-to-output isolation in the FARM. It is necessary to monitor Bus OK via an optoisolator if it is to be used on the secondary (output) side of the converters. A line-isolation transformer should be used when performing scope measurements. Scope probes should never be applied simultaneously to the input and output as this will damage the module.

Filter. (Figure 8–6) An integral input filter consists of a common-mode choke and Y-capacitors (line-ground) plus two X-capacitors (line-line). This filter configuration provides common-mode and differential- mode insertion loss in the frequency range between 100 kHz and 30 MHz.

Hold-up Capacitors. Hold-up capacitor values should be determined according to output bus voltage ripple, power fail hold-up time, and ride-through time. (Figure 8–7)

Many applications require the power supply to maintain output regulation during a momentary power failure of specified duration, i.e., the converters must hold up or ride through such an event while maintaining undisturbed output voltage regulation. Similarly, many of these same systems require notification of an impending power failure to allow time to perform an orderly shut down.

The energy stored in a capacitor which has been charged to voltage V is:

ε = 1/2(CV

) (1)

The power fail warning time (∆t) is defined as the interval

etween Bus OK and converter shut down (EN) as illustrated

b in Figure 8–7. The Bus OK and Enable thresholds are 205 V and 190 V, respectively. A simplified relationship between power fail warning time, operating power, and bus capac-

tance is obtained by inserting these constants:

C = 2P∆t / (205

– 1902)

C = 2P∆t / (5,925)

It should be noted that the series combination (C1, C2, Figure 8–3) requires each capacitor to be twice the calculated value, but the required voltage rating of each capacitor is reduced to 200 V. Allowable ripple voltage on the bus (or ripple current in the capacitors) may define the capacitance requirement. Consideration should be given to converter ripple rejection and resulting output ripple voltage.

For example, a converter whose output is 15 V and nominal input is 300 V will provide 56 dB ripple rejection, i.e., 10 V p-p of input ripple will produce 15 mV p-p of output ripple. (Figure 8–11) Equation 3 is again used to determine the required capacitance. In this case, V1 and V2 are the instantaneous values of bus voltage at the peaks and valleys (Figure 8–7) of the ripple, respectively. The capacitors must hold up the bus voltage for the time interval (∆t) between peaks of the rectified line as given by:

∆t = (π – θ) / 2πf (4)

where: f = line frequency

where: ε = stored energy

C = capacitance

V = voltage across the capacitor

Energy is given up by the capacitors as they are discharged by the converters. The energy expended

(the power-time product) is:

ε = P∆t = C(V1

– V22) / 2 (2)

where: P = operating power

The approximate conduction angle is given by:

Another consideration in hold-up capacitor selection is their ripple current rating. The capacitors’ rating must be higher than the maximum operating ripple current. The approximate operating ripple current (rms) is given by:

θ = rectifier conduction angle

(Figure 8–7)

θ = cos-1(V2 / V1) (5)

∆t = discharge interval

Irms = 2P / Vac (6)

V1 = capacitor voltage at the beginning of ∆t

where: P = total output power

V2 = capacitor voltage at the end of ∆t

Vac = operating line voltage

Rearranging Equation 2 to solve for the required capacitance:

C = 2P∆t / (V

– V22) (3)

Calculated values of bus capacitance for various hold-up time, ride-through time, and ripple-voltage requirements are given as a function of operating power level in Figures 8–8, 8–9, and 8–10, respectively.

Maxi, Mini, Micro Design Guide Rev 4.9 vicorpower.com

Page 38 of 88

Apps. Eng. 800 927.9474 800 735.6200

Page 40

Design Guide & Applications Manual

+IN

PC (GATE IN)

–IN

EMI GND

N/C

–

50 k

15 Vdc

Micro-

controller

Vicor DC-DC

Converter

FARM

ot used with VI-260/VI-J60

+IN

–IN

EMI GND

N/C

BOK

–

Vicor DC-DC

Converter

Micro-

controller

15 V dc

+5 V dc

econdary

eferenced

4.7 nF

EMI GND

N/C

0.47 µF

0.099 µF

330 µH

BOK

–

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

EXAMPLE

In this example, the output required from the DC-DC converter at the point of load is 12 Vdc at 320 W. Therefore, the output power from the FARM would be 375 W (assuming a converter efficiency of 85%). The desired hold-up time is 9 ms over an input range of 90 to 264 Vac.

Determining Required Capacitance for Power Fail Warning. Figure 8–8 is used to determine capacitance

NOTE: The warning time is not dependent on line voltage. A hold-up capacitor calculator is available on the Vicor website, at http://asp.vicorpower.com/calcu-

lators/calculators.asp?calc=4

8. Filter / Autoranging Rectifier Module (FARM)

etermining Ride-through Time. Figure 8–9 illustrates

ride-through time as a function of line voltage and output power, and shows that at a nominal line of 90 Vac, ridethrough would be 68 ms. Ride-through time is a function

f line voltage.

Determining Ripple Voltage on the Hold-up Capacitors. Figure 8–10 is used to determine ripple

voltage as a function of operating power and bus capacitance, and shows that the ripple voltage across the hold-up capacitors will be 12 V p-p.

Determining the Ripple on the Output of the DC-DC Converter. Figure 8–11 is used to determine the

ripple rejection of the DC-DC converter and indicates a ripple rejection of approximately 60 dB for a 12 V output. Since the ripple on the bus voltage is 12 Vac and the ripple rejection of the converter is 60 dB, the output ripple of the converter due to ripple on its input (primarily 120 Hz) will be 12 mV p-p.

Figure 8–4 — Enable (EN) function

Figure 8–6 — Internal filter

Maxi, Mini, Micro Design Guide Rev 4.9 vicorpower.com

Page 39 of 88

Apps. Eng. 800 927.9474 800 735.6200

Figure 8–5 — Bus OK (BOK) isolated power status indicator

Page 41

8. Filter / Autoranging Rectifier Module (FARM)

Operating Power (W)

Power Fail Warning Time (ms)

1000

750500250

(FARM2XXX)

(FARM1XXX)

Operating Power (W)

Ride-through Time (ms)

100

90 Vac 115 Vac

1000750500250

Total

capacitance

820 µF

Operating Power (W)

P-P Ripple Vol tage (Vac)

2200 µF1600 µF1300 µF

1000750500250

1100 µF

820 µF

680 µF

(FARM1XXX)

(FARM2XXX)

Output Voltage

Ripple Rejection (dB)

50301552

205 V 190 V

Power

Fail

Power Fail

Warning

Bus OK

Converter

Shut down

Hold-up Time

254 V

Ride-Through Time

Ripple (V p-p)

π – θ θ

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

Figure 8–7 — General timing diagram of bus voltage following interruption of the AC mains

Design Guide & Applications Manual

Figure 8–8 — Power fail warning time vs. operating power and

Figure 8–9 — Ride-through time vs. operating power

total bus capacitance, series combination of C1, C2 (Figure 8–3)

Figure 8–10 — Ripple voltage vs. operating power and bus capacitance, series combination of C1, C2 (Figure 8–3)

Maxi, Mini, Micro Design Guide Rev 4.9 vicorpower.com

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Apps. Eng. 800 927.9474 800 735.6200

Figure 8–11 — Converter ripple rejection vs. output voltage (Typical)

Page 42

Design Guide & Applications Manual

ARM3

–

INI

N/+

L/–

Filter

AC line Input

EMI GND

+IN

–IN

+IN

–IN

Vicor 300 Vin

DC-DC

Converter

R1R2C1

To additional converters

Part

C1,2 C

3 – 6 C7,8 C9,C10 R1,2 R3, R4 V1,2 V3 V5,V6 F1,2

D1,2 D3,D4

Description

Holdup capacitors 4,700 pF (Y2 type) Film Cap., 0.61 µF 0

.001 µF 150 kΩ, 0.5 W 250 Ω, 0.125 W M

OV 220 V 270 V MOV Bidirectional TVS Diode U

se recommended fusing for specific converters Diode (1N4006) 1N5817

Vicor Part Number

01000 34610

30234-220 30076

1.5KE51CA

00670

26108

Sizing PCB traces:

All traces shown in bold carry significant current and should be sized accordingly.

Holdup Box (HUB)

410 μF HUB820-S 1100 μF HUB2200-S 600 μF HUB1200-S 1350 μF HUB2700-S 900 μF HUB1800-S 1650 μF HUB3300-S

(Fig.1b)

Vicor 300 Vin

C-DC

Converter

N/+

L/–

C10

L2/N

Input

Output

Vicor Part Description Part Number

C1 1.0 02573

C2, C3 4,700 pF (Y2 type) 01000

C4 0.33 µF 00927

F1 10 A Wickman 194 Series

or Bussman ABC-10

L1, L2 27 µH 32012

L3 1.3 mH 32006

R1, R2 10Ω

R3 150 kΩ, 0.5 W

R4 2.2 Ω, 2 W

V1 MOV 30076

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

9. Modular AC Front-end System (ENMod)

The ENMod component power front-end system for EN compliance provides an effective solution for an AC front end of a power supply enabled with Vicor DC-DC

onverters. The ENMod system’s basic building blocks are

c the MiniHAM passive harmonic attenuation module, the

ARM3 autoranging AC-DC front-end module (Figure 9–3)

F and a discrete EMI filter.

The ENMod system provides transient / surge immunity, harmonic current attenuation (Figure 9–2) and EMI

(Fig.9–1b)

filtering, in addition to all of the power switching and control circuitry necessary for autoranging rectification, inrush current limiting, and overvoltage protection.

onverter enable and status functions for orderly

C power up / down control or sequencing are also

rovided. To complete the AC front-end configuration,

p the user only needs to add hold-up capacitors, EMI filter (Figure 9–1b), and a few discrete components.

Figure 9–1a — Offline power supply configuration

Figure 9–1b — Input EMI filter for EN55022, Class B compliance

Maxi, Mini, Micro Design Guide Rev 4.9 vicorpower.com

Page 41 of 88

Apps. Eng. 800 927.9474 800 735.6200

Page 43

9. Modular AC Front-end System (ENMod)

Harmonic Current

0.01

.10

1.00

10.00

345678910111213141516171819202122232425262728293031323334353637383940

Harmonic Number

Current (A)

Measured Values

Odd Harmonic Limits

Even Harmonic Limits

Microcontroller

PTC

Thermistor

+OUT

–OUT

Strap

BOK

trap

EMI

Filter

EMI GND

00 300 200 1

90–132 V

AC Line

Output

Bus

(Vdc)

Strap

PTC

Thermistor

Bypass

Converter

Enable

Bus OK

~150 ms

Power

Power Down

4.1

2.1

3.1

5.1

2.2

1.2

~150 ms

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

Design Guide & Applications Manual

Figure 9–2 — Measured harmonic current at 230 Vac, 575 W vs. EN spec limits (*Measured values of even harmonics are below 0.01 A)

Figure 9–3 — Functional block diagram: FARM3 module

Figure 9–4 — Timing diagram: Power-up / down sequence

Vdc output

⇒

Strap Engaged

Enable

Figure 9–5 — Start up at 120 Vac input

Maxi, Mini, Micro Design Guide Rev 4.9 vicorpower.com

Page 42 of 88

Bus OK

Apps. Eng. 800 927.9474 800 735.6200

Figure 9–6 — Start up at 240 Vac input

Enable

Bus OK

Page 44

Design Guide & Applications Manual

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

POWER-UP SEQUENCE (Figure 9–4)

1.1 Upon application of input power, the hold-up capacitors begin to charge. The thermistor limits the charge current, and the exponential time constant is determined by the hold-up capacitor value and the thermistor cold resistance. The slope (dV/dt) of the capacitor voltage versus time approaches zero as the capacitors become charged to the peak of the AC line voltage.

The switch that bypasses the inrush limiting PTC (positive-temperature coefficient) thermistor is open when power is applied, as is the switch that engages the strap for voltage doubling. In addition, the converter modules are disabled via the Enable (EN) line, and Bus OK (BOK) is high.

3.1 If the bus voltage is greater than 235 V as the slope approaches zero, the inrush limiting thermistor is bypassed. Below 235 V, it is not bypassed.

4.1 The converters are enabled ~150 ms after the thermistor bypass switch is closed.

5.1 Bus OK is asserted after an additional ~150 ms delay to allow the converter outputs to settle within specification.

9. Modular AC Front-end System (ENMod)

Vdc output

Iac input @2A / mV

Enable

Bus OK

Figure 9–7 — Power down from 120 Vac

Vdc output

Iac input @2A / mV

Enable

Bus OK

Figure 9–8 — Power down from 240 Vac

POWER-DOWN SEQUENCE (Figure 9–4)

When input power is turned off or fails, the following sequence occurs as the bus voltage decays:

1.2 Bus OK is de-asserted when the bus voltage falls below 210 Vdc.

Vdc output

2.2 The converters are disabled when the bus voltage falls below 190 Vdc. If power is reapplied after the converters are disabled, the entire power-up sequence is repeated. If a momentary power interruption occurs and power is reestablished before the bus reaches the disable threshold, the power-up sequence is not repeated, i.e., the power conversion system “rides through” the momentary

Figure 9–9 — Output overvoltage protection 240 Vac range

interruption.

Maxi, Mini, Micro Design Guide Rev 4.9 vicorpower.com

Page 43 of 88

Apps. Eng. 800 927.9474 800 735.6200

Enable

Bus OK

Page 45

9. Modular AC Front-end System (ENMod)

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

Design Guide & Applications Manual

FILTERING AND TRANSIENT PROTECTION

The ENMod system maintains the DC output bus voltage between 250 and 370 Vdc over the entire input-voltage range, which is compatible with all Vicor 300 V input converters. Autoranging automatically switches to the proper bridge or doubler mode at startup depending on the input voltage, eliminating the possibility of damage due to improper line connection. The ENMod system is rated at 575 W output power. These modules can serve as the AC front end for any number and combination of compatible converters as long as the maximum power rating is not exceeded.

FARM3 MODULE PIN DESCRIPTIONS

Strap (ST) Pin. In addition to input and output power pin connections, it is necessary to connect the Strap pin to the center junction of the series hold-up capacitors (C1, C2) for proper (autoranging) operation. Varistors V1 and V2 provide capacitor protection. The bleeder resistors (R1, R2) discharge the hold-up capacitors when power is switched off. Capacitors C7 and C8 are recommended if the hold-up capacitors are located more than 3 inches (75 mm) from the output pins.

CAUTION

: There is no input to output isolation in the ENMods, hence the –Out of the ENMods and thus the –In of the downstream DC-DC converter(s) are at

high potential. If it is necessary to provide an

a external enable / disable function by controlling the

C-DC converter’s PC pin (referenced to the –In) of

D the converter an opto-isolator or isolated relay should be employed.

Figure 9–10a — Peak detection

Enable (EN) Pin. The Enable pin must be connected to the PC pin of all converter modules to disable the converters during power up. Otherwise, the converters would attempt to start while the hold-up capacitors are being charged through the current limiting thermistor, preventing the bus voltage from reaching the thermistor bypass threshold, thus disabling the power supply. The Enable output (the drain of an N channel MOSFET) is internally pulled up to 15 V through a 150 kΩ resistor. (Figure 9–11)

A signal diode should be placed close to and in series with the PC pin of each converter to eliminate the possibility of control interference between converters. The Enable pin switches to the high state (15 V) with respect to the SR pin to turn on the converters after the power-up inrush is over. The Enable function also provides input overvoltage protection for the converters by turning off the converters if the DC bus voltage exceeds 400 Vdc. The thermistor bypass switch opens if this condition occurs, placing the thermistor in series with the input voltage, reducing the bus voltage to a safe level while limiting input current in case the varistors conduct. The thermistor bypass switch also opens if a fault or overload reduces the bus voltage to less than 180 Vdc. (Figure 9–3)

Figure 9–10b — Quasi-peak detection

Figure 9–10c — Average detection

Maxi, Mini, Micro Design Guide Rev 4.9 vicorpower.com

Page 44 of 88

Apps. Eng. 800 927.9474 800 735.6200

Page 46

Design Guide & Applications Manual

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

9. Modular AC Front-end System (ENMod)

Bus OK (BOK) Pin. (Figure 9–12) The Bus OK pin is intended to provide early-warning power fail information and is also referenced to the SR pin.

CAUTION: There is no input-to-output isolation in the ENMods. It is necessary to monitor Bus OK via an optoisolator if it is to be used on the secondary (output) side of the converters. A line-isolation transformer should be used when performing scope measurements. Scope probes should never be applied simultaneously to the input and output as this will damage the module.

L, N Pins. Line and neutral input.

+ / – Pins. Positive and negative outputs.

SR Pin. Signal return for BOK and EN outputs.

FOR MINIHAM MODULE PIN CONNECTIONS (Figure 9–1a)

Filter. (Figure 9–1b) The input EMI filter consists of differential and common-mode chokes,Y-capacitors (lineground), and X-capacitors (line-line). This filter configuration provides sufficient common-mode and differential-mode insertion loss in the frequency range between 100 kHz and 30 MHz to comply with the Class B conducted emissions limit, as illustrated in Figures 9–10a thru 9–10c.

Energy is given up by the capacitors as they are discharged by the converters. The energy expended (the power-time product) is:

ε = P∆t = C(V1

here: P = operating power

– V22) / 2 (2)

∆t = discharge interval

1 = capacitor voltage at the beginning of ∆t

2 = capacitor voltage at the end of ∆t

Rearranging Equation 2 to solve for the required capacitance:

C = 2P∆t / (V

– V22) (3)

The power fail warning time (∆t) is defined as the interval between Bus OK and converter shutdown (EN) as illustrated in Figure 9–13. The Bus OK and Enable thresholds are 205 V and 190 V, respectively. A simplified relationship between power fail warning time, operating power, and bus capacitance is obtained by inserting these constants in Equation (3):

C = 2P∆t / (2052– 1902)

C = 2P∆t / (5,925)

Hold-up Capacitors. Hold-up capacitor values should be determined according to output bus voltage ripple, power fail hold-up time, and ride-through time. (Figure 9–13) Many applications require the power supply to maintain output regulation during a momentary power failure of specified duration, i.e., the converters must hold-up or ride-through such an event while maintaining undisturbed output voltage regulation. Similarly, many of these same systems require notification of an impending power failure in order to allow time to perform an orderly shutdown.

The energy stored on a capacitor which has been charged to voltage V is:

ε = 1/2(CV

) (1)

where: ε = stored energy

C = capacitance

V = voltage across the capacitor

It should be noted that the series combination (C1, C2, Figure 9–1a) requires each capacitor to be twice the calculated value, but the required voltage rating of each capacitor is reduced to 200 V.

Allowable ripple voltage on the bus (or ripple current in the capacitors) may define the capacitance requirement. Consideration should be given to converter ripple rejection and resulting output ripple voltage.

Equation 3 is again used to determine the required capacitance. In this case, V1 and V2 are the instantaneous values of bus voltage at the peaks and valleys (Figure 9–13) of the ripple, respectively. The capacitors must hold up the bus voltage for the time interval (∆t) between peaks of the rectified line as given by:

∆t = (π – θ) / 2πf (4)

where: f = line frequency

θ = rectifier conduction angle

Maxi, Mini, Micro Design Guide Rev 4.9 vicorpower.com

Page 45 of 88

Apps. Eng. 800 927.9474 800 735.6200

Page 47

9. Modular AC Front-end System (ENMod)s

+IN

PC (GATE IN)

–IN

EMI GND

–

150 k

5 Vdc

Micro-

controller

icor DC-DC Converter

FARM3

BOK

ot used with VI-260/VI-J60

EMI GND

BOK

–

Micro-

controller

15 Vdc

27 kΩ

+5 Vdc

Secondary referenced

FARM3

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

Design Guide & Applications Manual

The approximate conduction angle is given by:

θ = cos

(V2 / V1) (5)

Irms = 2P / Vac (6)

where: P = total output power

ac = operating line voltage

Calculated values of bus capacitance for various hold-up time, ride-through time, and ripple voltage requirements are given as a function of operating power level in Figures 9–14, 9–15, and 9–16, respectively.

EXAMPLE

In this example, the output required from the DC-DC converter at the point of load is 12 Vdc at 320 W. Therefore the output power from the ENMods would be 375 W (assuming a converter efficiency of 85%). The desired hold-up time is 9 ms over an input range of 90 to 264 Vac.

Determining the Ripple on the Output of the DC-DC Converter. Figure 9–17 is used to determine

the ripple rejection of the DC-DC converter and indicates

ripple rejection of approximately 60 dB for a 12 V

a output. Since the ripple on the bus voltage is 12 Vac

nd the ripple rejection of the converter is 60 dB, the

a output ripple of the converter due to ripple on its input (primarily 120 Hz) will be 12 m Vp-p.

A variety of hold-up capacitor options are available. Please visit our website at

http://asp.vicorpower.com/calculators/calculators.asp?ca lc=4.

Figure 9–11 — Enable (EN) function

Determining Required Capacitance for Power Fail Warning. Figure 9–14 is used to determine capacitance

for a given power fail warning time and power level, and shows that the total bus capacitance should be at least 820 µF. Since two capacitors are configured in series, each capacitor should be at least 1,640 µF. Note that warning time is not dependent on line voltage. A hold-up capacitor calculator is available on the Vicor website, at

http://asp.vicorpower.com/calculators/calculat-

ors.asp?calc=4.

Determining Ride-through Time. Figure 9–15 illustrates ride-through time as a function of line voltage and output power, and shows that at a nominal line of

Figure 9–12 — Bus OK (BOK) isolated power status indicator

90 Vac, ride-through would be 68 ms. Ride-through time is a function of line voltage.

Determining Ripple Voltage on the Hold-up Capacitors. Figure 9–16 is used to determine ripple

voltage as a function of operating power and bus capacitance, and shows that the ripple voltage across the hold-up capacitors will be 12 Vp-p.

Maxi, Mini, Micro Design Guide Rev 4.9 vicorpower.com

Page 46 of 88

Apps. Eng. 800 927.9474 800 735.6200

Page 48

Design Guide & Applications Manual

205 V 190 V

Power

Fail

Power Fail

Warning

Bus OK

Converter

Shut down

Hold-up Time

254 V

Ride-Through Time

Ripple (V p-p)

π – θ θ

Operating Power (W)

500

250

Power Fail Warning Time (ms)

2,200 µF1,600 µF1,300 µF

1,100 µF

20 µF

80 µF

Operating Power (W)

Ride-through Time (ms)

0 Vac 1 15 Vac

500

250

Operating Power (W)

P-P Ripple Voltage (Vac)

500250

2,200 µF1,600 µF1,300 µF

1,100 µF

820 µF

680 µF

Output Voltage

Ripple Rejection (dB)

50301552

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

9. Modular AC Front-end System (ENMod)

Figure 9–13 — General timing diagram of bus voltage following interruption of the AC mains

Figure 9–14 — Power fail warning time vs. operating power and

Figure 9–15 — Ride-through time vs. operating power

total bus capacitance, series combination of C1, C1 (Figure 9–1a)

Figure 9–16 — Ripple voltage vs. operating power and bus capacitance, series combination of C1, C1 (Figure 9–1a)

Maxi, Mini, Micro Design Guide Rev 4.9 vicorpower.com

Page 47 of 88

Figure 9–17 — Converter ripple rejection vs. output voltage (Typical)

Apps. Eng. 800 927.9474 800 735.6200

Page 49

10. High Boost HAM

Note: Non-Isolated Output

Gate In

Gate Out

ZCS

Boost

Converter

Inrush

& Short

Circuit

Protection

High Frequency Control

Voltage

Waveform

Current

Sense

Line

Control

& House-

keeping Circuitry

Output Voltage

Module Enable

Power OK

DC Out

Recti-

fier

Aux. Supply

–

NOTE: No input to output isolation.

Input Voltage

VRMS

Rated Output Power

Output Voltage

Output Power (W)

Output Voltage (Vdc)

Vin

THE HIGH-BOOST HARMONIC ATTENUATOR MODULE COMPATIBLE WITH V375, VI-26x AND VI-J6x FAMILIES

The High-Boost Harmonic Attenuation Module (HAM) consists of a full-wave rectifier, a high-frequency zerocurrent-switching (ZCS) boost converter, active inrush current limiting, short-circuit protection, control, and housekeeping circuitry (Figure 10–1). The incoming AC line is rectified and fed to the boost converter. The control circuitry varies the operating frequency of the boost converter to regulate and maintain the output voltage of the HAM above the peak of the incoming line, while forcing the input current to follow the waveshape and phase of the line voltage. A power factor better than 0.99 is achieved (Figure 10–2). Operating efficiency of the boost converter is optimized at any incoming line voltage by an adaptive output voltage control scheme.

The output voltage of the HAM is a function of incoming AC line voltage (Figure 10–3). On a nominal 115 Vac line, the output voltage of the HAM is 280 Vdc — well within the input operating voltage range of Vicor V375 DC-DC converters. Above 180 V input, the output voltage linearly increases with input voltage. At 230 Vac the delivered voltage will be approximately 365 V. For any given input line voltage, the HAM maintains enough headroom between the output voltage and peak input voltage to ensure high quality active power factor correction without sacrificing operating efficiency.

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

Figure 10–2 — Input voltage and current wave forms, without and with power factor correction.

Design Guide & Applications Manual

The HAMD version does not contain an internal bridge rectifier and is intended for configuring higher power arrays with Booster versions, referred to as the VI-BAMD (Figure 10–5).

Figure 10–1 — HAM block diagram (HAMD version has the rectifier block deleted.)

Maxi, Mini, Micro Design Guide Rev 4.9 vicorpower.com

Page 48 of 88

Figure 10–3 — Output voltage and power rating vs. input voltage

L1 and L2/N (HAM) Pin. An appropriate line filter is required to limit conducted emissions and ensure reliable

operation of the HAM, see page 51. Connect single phase AC mains to the input of the line filter via a 10 A, 250 V fuse. Connect the output of the filter to L1 and L2/N of the HAM. Do not put an X-capacitor across the input of the HAM or use a line filter with an X-capacitor on its output as power factor correction may be impacted.

+IN, –IN (HAMD, BAMD) Pin. These pins are connected to the output of the external bridge rectifier in HAMD /

BAMD configurations (Figure 10–5).

GATE IN (HAM) Pin. The user should not make any connection to this pin.

Apps. Eng. 800 927.9474 800 735.6200

GATE IN (HAMD) Pin. This pin provides line voltage envelope and phase information for power factor

correction. This connection must be made through the synchronization diodes between the line filter and bridge rectifier (Figure 10–5).

Page 50

Design Guide & Applications Manual

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

10. High Boost HAM

GATE IN (BAMD) Pin. The Gate In pin is an interface pin to the Gate Out pin of a HAMD or BAMD depending on

onfiguration. The user should not make any other

c connection to this pin.

GATE OUT Pin. The Gate Out pin is a synchronization pin for HAMD/BAMD arrays; the user should not make any other connection to this pin.

+OUT and -OUT Pin. Connect the +OUT of the HAM to the +IN of the respective Vicor DC-DC converters with the recommended fuse. Connect the -OUT of the HAM to the

-IN of the converters. In addition, an external hold-up capacitor of 1,000 µF with a minimum voltage rating of 450 Vdc, is required (across the output of the HAM) for 16 ms ride through time at full power (500 µF for half power, etc). This capacitor must be in close proximity to the HAM. Do not exceed 3,000 µF of total output capacitance. Lower values of capacitance may be used for reduced hold up requirements, but not less than 500 µF. Lower capacitance values may degrade power factor specifications.

Auxiliary Supply (A/S) Pin. The HAM provides a low voltage non isolated output Auxiliary Supply (A/S) that may be used to power primary side control and monitoring circuitry. This output is 19 – 23 Vdc, referenced to -OUT, at 3 mA max. Do not overload or short this output as the HAM will fail. A typical use for A/S is to power an optical coupler that isolates the Power OK signal (Figure 10-6).

Enable Output (E/O) Pin. The Enable Output (E/O) is used to inhibit the DC-DC converters at start up until the hold up capacitors are charged, at which time Enable is asserted high (open state, Figure 10–8). If the AC line fails, E/O goes low when the DC output of the HAM drops below 250 Vdc.

E/O must be connected to the Gate Input of all VI-26x and VI-J6x drivers and/or the PC pin of the V375 DC-DC converters (Figure 10-4); failure to do so may cause the converters to toggle on and off. If an external load is connected directly to the output of the HAM, do not apply the load until the output hold up capacitor(s) are fully charged.

In applications using VI-26x drivers and VI-26x boosters, the E/O pin should be connected to the Gate In pin of the driver module only, it is not necessary to connect this pin to boosters as they are controlled by their respective driver.

The E/O pin ancillary circuitry illustrated in Figures 10–4 and 10–5 provides transient immunity. The illustrated circuitry is the minimum required, see Figures 10–4 and 10–5.

Power OK (P/OK) Pin. Power OK is a monitor signal that indicates the status of the AC mains and the DC output voltage of the HAM. P/OK is asserted (active low) when

the output bus voltage is within normal operating range (>270 Vdc) and 20 – 25 ms after DC-DC converters are

nabled by the E/O signal of the HAM. This provides suffi-

e cient time for the converters to turn on and their output(s) to stabilize prior to P/OK being asserted, (Figure 10–9). For momentary interruptions of AC power, the HAM will provide at least 16 ms of ride through or hold up time (with 1,000 µF output capacitor). On loss of power or brownout, (when the HAM output voltage drops below 270 Vdc) the P/OK signal will go to an open circuit state (Figure 10–7), signaling an impending loss of input power to the converter modules. P/OK will provide power fail warning at least 1 ms prior to converter shut down. When the HAM output voltage drops below 250 Vdc the converters are disabled via Enable Output (E/O).

NOTE: Acoustic Noise. Audible noise may be emitted from the module under no load, light load, or dynamic loading conditions. This is considered normal operation of the module.

SAFETY NOTES

Each HAM, HAMD or BAMD module must be preceded by a safety agency recognized fast-blow 10A 3AG fuse.

The HAM is not isolated from the line – either input or output; a line isolation transformer must be used when making scope measurements. HAMs do not provide input to output isolation. Differential probes should be used when probing the input and output simultaneously to avoid destructive ground loops.

PROTECTIVE FEATURES

Over Temperature Shut Down. The HAM is designed to shut down when the temperature of the baseplate exceeds 90 °C. Do not operate the HAM above its maximum operating temperature of 85°C.

Short Circuit Protection. The HAM contains output short circuit protection. Operation of this function does not clear the input fuse and the output will resume normal operation after removal of the fault. A short period of time may be required to allow for cooling of an internal temperature sensor.

Output Over Voltage Protection. The HAM contains output over voltage protection. In the event the output voltage exceeds approximately 420 Vdc, the boost will decrease to maintain 420 Vdc on the output. When the peak of the AC line exceeds 420 V (approximately 293 Vac) the boost will have been reduced to zero and the E/O line will be pulled low shutting down the converters. Beyond this the protection circuit will be enabled and the output voltage will decrease.

Maxi, Mini, Micro Design Guide Rev 4.9 vicorpower.com

Page 49 of 88

Apps. Eng. 800 927.9474 800 735.6200

Page 51

10. High Boost HAM

Component Description Vicor Designation Part Number

C1 0.1 µF ceramic, 50 V C2, C3 0.01 µF ceramic, 50 V C4 Hold up capacitor, Available as a HUB 1000 to 6000 µF from Vicor (see adjoining table) C5–C8 4,700 pF Y2 cap. 01000 C9,C10 0.2 µF, 500 V Film or Ceramic D1 1N4691

zener, 6.2 V

D2, D3 1N4006

diode, 800 V

00670

D4, D5 1N5817

schottky diode, 20 V 26108 F1, F2 Use recommended fusing for specific DC-DC Converters F3 20 A, 250 V R1 50 KΩ R2, R3 250 Ω, 0

.25 W

R4** 100 K

, 2 W V1 275 V MOV 30076 Z1, Z2 130 V Transorb 1.5KE130CA Z3 150 V Transorb 1.5KE150CA

+IN

V375 DC-DC Converters

-IN

+IN

C6 C

JMK Filter

P/N 1319-13

12.6 A*

+IN

GATE IN

GATE OUT

-IN

+OUT

-OUT

P/OK

A/S

VI-HAMD-xL

GATE IN

GATE OUT

-IN

+IN

+OUT

-OUT

VI-BAMD-xL

Input

Bridge Rectifier Vicor P/N 30660

GND

L2/N

1N4006

N4006

R4**

* Consult Vicor's Applications Engineering for specific HAMD / BAMD filtering information. ** A 100 KΩ, 2 W resistor is used for every 1,000 µF of hold up capacitance.

Hold up Box (HUB)

10 A

2000 µF HUB1000-P 1350 W

+IN

-IN

L2/N

ATE OUT

GATE IN

– OUT

E/O

+ OUT

A/S

/OK

VI-HAM-xL

-IN

-Capacitor

+IN

L2/N

LOAD

L2/N

icor

Line Filter

/N 30205

.3 A

LINE

GATE IN

GATE OUT

Hold up Box (HUB)

R3*

V375

DC-DC

Converters

VI-26x or

VI-J6x

DC-DC

Converters

Component Description Vicor D

esignation Part Number

1 0.1 µF ceramic, 50 V

2, C3 0.01 µF ceramic, 50 V

4 Hold up capacitor, Available as a HUB

500 to 3,000 µF from Vicor (see

adjoining table) R1 50 KΩ R

2 250 Ω, 0

25 W

R3* 100 K

, 2 W

1 1N4691 zener, 6.2 V D2, D3 1N4006 diode, 800 V 00670 D

4, D5 1N5817 schottky diode, 20V 26108 V1 275 V MOV 30076 C5–C8 4,700 pF Y2 cap. 01000 F

1, F2 Use recommended fusing for specific DC-DC Converters F

3 10 A, 250 V

µF µ

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

Design Guide & Applications Manual

Figure 10–4 — Connection diagram HAM / DC-DC converter

Figure 10–5 — Connection diagram, HAMD / BAMD / V375 DC-DC converters

HAMD-CL Driver HAM: No internal bridge rectifier or synchronization diodes. BAMD-CL Booster HAM: Companion module to HAMD-CM used for additional output power. No internal bridge rectifier.

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Page 50 of 88

Apps. Eng. 800 927.9474 800 735.6200

Page 52

Design Guide & Applications Manual

LINE

LOAD

HAM Filter P/N 30205

R = 235 KΩ D1,2 = 1.5KE130CA D3 = 1.5KE150CA

MOV*

P/N 30076

Cx = 1.5 uF(x2)SH C

= 0.01 uF, Y2 type LC = 6.9 mH LD = 0.72 mH

*MOV required external to filter to meet normal mode transient surge requirements

+OUT

P/OK

–OUT

E/O

A/S

18 kΩ, 1/4 W

"Power OK" Status

Low = OK

LOGIC

P/OK

–

OUT

A/S

LOGIC

–OUT

OUT

/OK

A/S

Outputs

DC-DC Converter(s)

Rectified Line

Enable Output (E/O)

DC Output

f HAM

ower OK (P/OK)

AC Mains 120 Vrms

Boost Voltage

250 Vdc

80 Vdc

ff at 250 Vdc

Off at 270 Vdc

270 Vdc

5 ms

10 ms

Off below 250 Vdc

E/O

P/OK

+OUT

–OUT

≤ 3 mA

19 – 23 V

–

DO NOT OVERLOAD or directly connect a capacitor to the A/S terminal.

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

10. High Boost HAM

Figure 10–6 — Auxiliary Supply (A/S)

Figure 10–8 — Enable Output (E/O)

LINE FILTER FOR HIGH BOOST HAM

A line filter is required to provide attenuation of conducted emissions generated by the HAM module and to protect it from line transients. It also presents a well defined high frequency AC line impedance to the input of the HAM. To meet the listed specifications, Vicor’s P/N 30205 line filter/transient suppressor or equivalent must be used, see Figure 10–10. The addition of a MOV external to this filter is required to meet normal mode transient surge requirements.

For applications using HAMD + BAMD or where the user desires to construct a custom HAM filter, the filter should be designed following Figure 10–10, the schematic of Vicor’s P/N 30205 filter. The current carrying capability of the inductors must be scaled proportionally to the number of HAM modules used. Inductance values must be selected according to Table 10–1. These limits are to ensure proper operation of the HAM and do not guarantee a system will meet conducted emissions specifications.

For applications requiring magnetic field shielding, do not place a ferrous EMI shield over the plastic cover of the HAM module. This can cause thermal problems due to induction heating effects.

Maxi, Mini, Micro Design Guide Rev 4.9 vicorpower.com

Page 51 of 88

Figure 10–7 — Power OK (P/OK)

Figure 10–9 — Start-up / shut-down timing diagram

Figure 10–10 — Recommended HAM filter

Parameter Min Typ Max Unit

Differential Mode Inductance (LD)

Common Mode Inductance (LC)

Table 10-1 — HAM filter inductance range

Apps. Eng. 800 927.9474 800 735.6200

0.2 0.35 0.75 mH

36 mH

Page 53

10. High Boost HAM

OPERATING TEMP (DEG C)

CURRENT (AMPS)

RATED CURRENT VS AMBIENT TEMPERATURE

1.0 2.0 3.0 4.0 5.0 6.0 7.0

0.01 0.04 0.1 0.4 1 4 10 40 100

0.02 0.07 0.2 0.7 2 7 20 70 FREQUENCY (MEGAHERTZ)

INSERTION LOSS (db)

FACE MAY BE

BOWED 0.04 MAX

4-40 INSERT

0.25 DP 4 PL

ø0.080 PIN

6 PLACES

LOAD

LINE

0.900

0.100

1.200

0.500

4.60 ±0.02

0.060

1.00 MAX

0.13 ±0.02

1.45 ±0.02

2.800

2.50

2.00

.30 ±0.02

.800

2.40±0.02

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

Design Guide & Applications Manual

Figure 10–11 — HAM filter mechanical diagram

Figure 10–12 — HAM filter’s current rating vs. temperature

Figure 10–13 — HAM filter insertion loss vs. frequency

Parameter Min Typ Max Unit

Operating voltage 85 250 Vac Operating temperature (See Fig.10-12) –20 50 °C

Leakage current at 264 Vac, 63 Hz (Either line to earth)

Operating current 6.3 A Dielectric withstand (line – case) 1500 Vac Residual voltage after 1 sec. 34 V Operating frequency 50 60 Hz Agency Approvals UL, CSA, TÜV

1.2 mA

Table 10-2 — HAM filter part #30205 specifications

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Apps. Eng. 800 927.9474 800 735.6200

Page 54

Design Guide & Applications Manual

+OUT

–S

–OUT

–IN

+IN

Note: The FIAM is shown in the on state. To disable,

open the connection between ON/OFF and –Out.

External Reverse Polarity Protection

FIAM

–

GND

+IN

+OUT

OFF

–OUT

Mini, Maxi, Micro

DC-DC Converter

0.2 µF

Input

4,700 pF

0.01 µF

.01 µF

+OUT

-OUT

-IN

+IN

EMI Filter

Charge Pump /

Control

ON/OFF

EMI GND

Transient Suppression

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

Description:

11. Filter Input Attenuator Module (FIAM) Family

The FIAM family of front-end modules (Figure 11–1) provides EMI filtering, transient protection, and inrush current limiting in DC-DC applications. The FIAM enables designers using Vicor Maxi, Mini, and Micro DC-DC con-

verters, and in select cases VI Chip®based devices, to meet the transient immunity and EMI requirements of the standards referenced in the respective model datasheet.

Theory of Operation:

Refer to the simplified FIAM block diagram Figure 11-2.

Internally, the FIAM employs a transient suppressor directly across the input. A passive EMI filter that is tuned to attenuate both common-mode and differential-mode conducted emissions follow this.

When the FIAM ON/OFF control pin is tied to - OUT the device is set to "ON" and will provide an output upon application of input voltage.

When power is applied, the charge pump / control circuit drives the gate of the MOSFET in series with the positive rail (Q1). The charge pump limits the time rate of change of the gate bias voltage, which results in a controlled voltage ramp-up - this limits the rate at which the external output capacitor is charged, thereby limiting the system inrush current.

During normal operation Q1 is fully enhanced - essentially a closed switch.

Surge protection is accomplished by robbing gate charge of the Q1 by the bottom MOSFET Q2. During this condition, the source terminal of the Q1 follows the gate, offset by the gate threshold voltage. A transient surge event at the input, or drain terminal of the Q1 is therefore attenuated and absorbed by Q1 while in the source follower mode. As a result, the transient surge is not propagated to the output of the FIAM.

Removing the ON/OFF connection shuts down the charge pump and turns off Q1.

Figure 11–1 — Typical application (FIAM)

Figure 11–2 — Block diagram (FIAM)

Maxi, Mini, Micro Design Guide Rev 4.9 vicorpower.com

Page 53 of 88

Apps. Eng. 800 927.9474 800 735.6200

Page 55

11. Filter Input Attenuator Module (FIAM) Family

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

IAM1 FIAM2 M-FIAM3 Notes

Input voltage 36 – 76 Vdc 36 – 76 Vdc 180 – 375 Vdc Continuous Recommended fusing (F1): Bussman ABC–10 Bussman ABC-20 Bussman ABC-3 Output current: 10 A 20 A 3 A Maximum External capacitance (C1) 10 µF min – 150 µF max 100 µF min – 330 µF max 10 µF min – 22 µF max Inrush limiting 0.014 A/µF 0.014 A/µF 0.018 A/µF Maximum

EMI/RFI

Transient immunity

Mini package size 2.28" x 2.2" x 0.5" 2.28" x 2.2" x 0.5" 2.28" x 2.2" x 0.5"

Bellcore GR-001089-Core, Bellcore GR-001089-Core, MIL-STD-461E, CE101 EN55022 Class B, FCC EN55022 Class B, FCC CE102, CS101, CS114

Part 15 Class B Part 15 Class B CS115, CS116 Bellcore TR-NWT-0004999, Bellcore TR-NWT-0004999, Exceeds limits of MIL-STDETS 300 386-1, Class 2 ETS 300 386-1, Class 2 704E/F

Design Guide & Applications Manual

M-FIAM5B M-FIAM9 Notes

Input voltage 14 – 36 Vdc 10 – 36 Vdc Continuous Recommended fusing (F1): Bussman ABC-20 Bussman ABC-20 Output current: 20 A 18 A Maximum External capacitance (C1) 330 µF min –1000 µF max 330 µF min –1000 µF max Inrush limiting 0.007 A/µF 0.007 A/µF Maximum

EMI/RFI

Transient immunity

Mini package size 2.28" x 2.2" x 0.5" 2.28" x 2.2" x 0.5"

MIL-STD-461E, CE101 MIL-STD-461E, CE101 CE102, CS101, CS114 CE102, CS101, CS114

CS115, CS116 CS115, CS116 50 V Max. 12.5 ms per MIL- 100 Vdc 50 ms per MIL-STDSTD-704E/F, cont. operation 1275A/B/D, 250 Vdc 70 µs

per MIL-STD-1275A/B/D, 70 Vdc 20 ms per MIL-STD-704A. 50 Vdc 12.5 ms per MIL-STD704E/F, cont. operation

Table 11–1 — FIAM Family Specifications (See specific data sheets for more detail)

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Apps. Eng. 800 927.9474 800 735.6200

Page 56

Design Guide & Applications Manual

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

11. Filter Input Attenuator Module (FIAM) Family

Figure 11–3 — FIAM and model V48A12C500B DC-DC converter Conducted Emissions Typical

Figure 11–5 — Transient immunity: FIAM output response to an input transient Typical

Figure 11–4 — FIAM and model V48B24C250B DC-DC converter Conducted Emissions Typical

Figure 11–6 — Inrush limiting: Inrush current with 330 µF external capacitance Typical

Maxi, Mini, Micro Design Guide Rev 4.9 vicorpower.com

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Apps. Eng. 800 927.9474 800 735.6200

Page 57

12. Output Ripple Attenuator Module (MicroRAM)

DC-DC

Converter

+OUT

Vref

–OUT

+IN

TRAN

–IN

+OUT

–S

–

OUT

+IN

–IN

RSENSE

5.1

22 m F

RAN

ptional Component

RHR

CHR*

OAD

DC-DC

Converter

+OUT

–

OUT

–IN

μRAM

+OUT

Vref

–OUT

TRAN

–IN

RSC RHR

CTRAN*

HR*

*Optional Component

0 kΩ

1 µF

IRML6401

LOAD

Figure 12–1a — Typical configuration using remote sense

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

Design Guide & Applications Manual

Figure 12–1b — Typical configuration using SC control (Optional CHR, 25 µF maximum in SC configuration.)

FUNCTIONAL DESCRIPTION

The MicroRAM has an internal passive filter, (Figure 12–2) that effectively attenuates ripple in the 50 kHz to 1 MHz range. An active filter provides attenuation from low frequency up to the 1 MHz range. The user must set the headroom voltage of the active block with the external RHR resistor to optimize performance. The MicroRAM must be connected as shown in Figures 12–1a or 12–1b depending on the load-sensing method. The transient load current performance can be increased by the addition of optional C

TRAN capacitance to the CTRAN pin. The low-

frequency ripple attenuation can be increased by addition of optional CHR capacitance to the VREF pin as shown in Figures 12–3a and 12–3b.

Transient load current is supplied by the internal C

TRAN

capacitance, plus optional external capacitance, during the time it takes the converter loop to respond to the increase in load. The MicroRAM’s active loop responds in roughly one microsecond to output voltage perturbations. There are limitations to the magnitude and the rate of change of the transient current that the MicroRAM can sustain while the converter responds. See Figures 12–8 through

Maxi, Mini, Micro Design Guide Rev 4.9 vicorpower.com

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Apps. Eng. 800 927.9474 800 735.6200

12–16 for examples of dynamic performance. A larger headroom voltage setting will provide increased transient performance, ripple attenuation, and power dissipation while reducing overall efficiency. (Figures 12–4a, 12–4b, 12–4c, and 12–4d)

The active loop senses the output current and reduces the headroom voltage in a linear fashion to approximate constant power dissipation of MicroRAM with increasing loads. (Figures 12–7, 12–8 and 12–9) The headroom setting can be reduced to decrease power dissipation where the transient requirement is low and efficient ripple attenuation is the primary performance concern.

The active dynamic headroom range is limited on the low end by the initial headroom setting and the maximum expected load. If the maximum load in the application is 10 A, for example, the 1 A headroom can be set 75 mV lower to conserve power and still have active headroom at the maximum load current of 10 A. The high end or maximum headroom range is limited by the internal ORing diode function.

Page 58

Design Guide & Applications Manual

+Out

Vref

–Out

+In

TRAN

–In

Passive

Block

Active

Block

Control

Ripple Attenuation @ 28 V (Room Temp.)

-80.00

-60.00

-40.00

-20.00

0.00

20.00

10 1001,00010,000 100,000 1,000,000 10,000,000

Freq. (Hz)

Gain (dB)

10 A, 100 uF Vref 10 A, No Vref Cap

Ripple Attenuation @ 5 V (Room Temp.)

-80.00

-60.00

-40.00

-20.00

0.00

20.00

10 100 1,000 10,000 100,0001,000,00010,000,000

Freq. (Hz)

Gain (dB)

10 A, 100 uF Vref 10 A, No Vref Cap

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

12. Output Ripple Attenuator Module (MicroRAM)

The SC or trim-up function can be used when remote sensing is not available on the source converter or is not desirable. It is specifically designed for converters with a

.23 V reference and a 1 kΩ input impedance like Vicor

1 Maxi, Mini, Micro converters. In comparison to remote sensing, the SC configuration will have an error in the load voltage versus load current. It will be proportional to the output current and the resistance of the load path from the output of the MicroRAM to the load.

The ORing feature prevents current flowing from the output of the MicroRAM back through its input terminal in a redundant system configuration in the event that a converter output fails. When the converter output supplying the MicroRAM droops below the ORed output voltage potential of the redundant system, the input of the MicroRAM is isolated from it’s output. Less than 50 mA will flow out of the input terminal of the MicroRAM over the full range of input voltage under this condition.

Load capacitance can affect the overall phase margin of the MicroRAM active loop as well as the phase margin of the converter loop. The distributed variables such as

nductance of the load path, the capacitor type and

i value as well as its ESR and ESL also affect transient capa-

ility at the load. The following guidelines should

b be considered when point-of-load capacitance is used with the MicroRAM in order to maintain a minimum of 30 degrees of phase margin.

1. Using ceramic load capacitance with <1 mΩ ESR and <1 nH ESL:

a. 20 µF to 200 µF requires 20 nH of trace / wire

load path inductance

b. 200 µF to 1,000 µF requires 60 nH of trace / wire

load path inductance

2. For the case where load capacitance is connected directly to the output of the MicroRAM, i.e. no trace inductance, and the ESR is >1 mΩ:

a. 20 µF to 200 µF load capacitance needs an ESL

of >50 nH

b. 200 µF to 1,000 µF load capacitance needs an

ESL of >5 nH

Figure 12-2 — MicroRAM block diagram

Figure 12–3a — The small signal attenuation performance as

measured on a network analyzer with a typical module at 28 V and 10 A output. The low frequency attenuation can be enhanced by connecting a 100 µF capacitor, C Figures 12–1 and 12–2.

Maxi, Mini, Micro Design Guide Rev 4.9 vicorpower.com

Page 57 of 88

HR, to the VREF pin as shown in

Apps. Eng. 800 927.9474 800 735.6200

3. Adding low ESR capacitance directly at the output terminals of MicroRAM is not recommended and may cause stability problems.

4. In practice, the distributed board or wire inductance at a load or on a load board will be sufficient to isolate the output of the MicroRAM from any load capacitance and minimize any appreciable effect on phase margin.

Figure 12–3b — The small signal attenuation performance as measured on a network analyzer with a typical module at 5 V and 10 A. The low frequency attenuation can be enhanced by connecting a 100 µF capacitor, C 12–1 and 12–2.

HR, to the VREF pin as shown in Figures

Page 59

12. Output Ripple Attenuator Module (MicroRAM)

requency

10 Hz 100 Hz 1.0 KHz 10 KHz 100 KHz 1.0 MHz

... DB(V(VOUT))

-75

-50

-25

Rhr = 260 k (Vheadroom = 90 mV)

250 k (100 mV)

240 k (110 mV)

230 k (122 mV)

220 k (135 mV)

210 k (150 mV)

00 k (160 mV)

190 k (180 mV)

180 k (197 mV)

170 k (217 mV)

160 k (240 mV)

150 k (260 mV)

out = 28 V load = 20 A

100 degrees baseplate temperature

17 k

18 k

19 k

20 k

21 k

22 k

23 k

24 k

25 k

26 k

27 k

Rhr=28 k

-70

-60

-50

-40

-30

-20

-10

3.0 3.5 4.0 4.5 5.0 5.5 6.0

Watts

500 khz 3 V 1 Mhz 3 V

100 khz 3 V

Rhr = 260 k

250 k

240 k

230 k

220 k

210 k

200 k

190 k

180 k

170 k

160 k

150 k

-70

-60

-50

-40

-30

-20

-10

3.0 3.5 4.0 4.5 5.0 5.5 6.0

Watts

100 khz 28 V 500 khz 28 V 1 Mhz 28 V

requency

0 Hz

00 Hz

.0 KHz

0 KHz

00 KHz

.0 MHz

.. DB(V(VOUT))

-75

-0 Vout = 3 V load = 20 A

100 degrees baseplate temperature

Rhr = 28 k (Vheadroom = 90 mV)

7 k (100 mV)

2 k (160 mV)

3 k (150 mV)

24 k (135 mV)

25 k (122 mV)

6 k (110 mV)

17 k (260 mV)

18 k (240 mV)

9 k (217 mV)

20 k (197 mV)

21 k (180 mV)

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

Design Guide & Applications Manual

Figure 12–4a — Graph of simulated results demonstrating the tradeoff of attenuation vs. headroom setting at 20 A and a equivalent 100°C baseplate temperature at 3 V.

Figure 12–4b — Graph of simulated results demonstrating the tradeoff of attenuation vs. headroom setting at 20 A and a equivalent 100°C baseplate temperature at 28 V.

Figure 12–4c —

MicroRAM attenuation vs. power dissipation at 3 V, 20 A

Maxi, Mini, Micro Design Guide Rev 4.9 vicorpower.com

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Apps. Eng. 800 927.9474 800 735.6200

Figure 12–4d—MicroRAM attenuation vs. power dissipation at 28 V, 20 A

Page 60

Design Guide & Applications Manual

load

2A 4A 6A 8A 10A 12A 14A 16A 18A 20A1A

200 mV

00 mV

400 mV

450 mV

3 V

20k

Rhr=16k

17k

18k

19k

21k

headroom

2 A 4 A 6 A 8 A 10 A 12 A 14 A 16 A 18 A 20 A1 A

200 mV

300 mV

400 mV

450 mV

00 k

90 k

5 k

95 k

105 k

hr = 80 k

load

headroom

OUT

= 15 V

2 A 4 A 6 A 8 A 10 A 12 A 14 A 16 A 18 A 20 A1 A

200 mV

300 mV

400 mV

450 mV

OUT

=28 V

190k

Rhr=150k

160k

170k

180k

200k

load

headroom

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

Figure 12–5 — Headroom vs. load current at 3 V output

12. Output Ripple Attenuator Module (MicroRAM)

Figure 12–6 — Headroom vs. load current at 15 V output

Figure 12–7 — Headroom vs. load current at 28 V output

Maxi, Mini, Micro Design Guide Rev 4.9 vicorpower.com

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Apps. Eng. 800 927.9474 800 735.6200

Page 61

12. Output Ripple Attenuator Module (MicroRAM)

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

Design Guide & Applications Manual

Figure 12–8 — V375A28C600B and µRAM: Input and output ripple @ 50% (10 A) load CH1 = Vi; CH2 = Vo; Vi – Vo = 332 mV; R

HR = 178 k

Figure 12–10 — V375A28C600B and µRAM; Input and output dynamic response CTRAN = 820 µF Electrolytic; 33% of load step of

6.5 A (10 A–16.5 A); RHR = 178 k (Configured as in Figures 14–1a and 14–1b)

Figure 12–9 — V375A28C600B and µRAM; Input and output dynamic response no added CTRAN; 20% of 20 A rating load step of 4 A (10 A – 14 A); R

HR = 178 k (Configured as in Figures 14–1a and 14–1b)

Figure 12–11 — V375B12C250B and µRAM; Input and output ripple

@50% (10 A) load CH1=Vi; CH2=Vo; Vi – Vo=305 mV; R (Configured as in Figures 14–1a and 14–1b)

HR = 80 k

Figure 12–12 — V300B12C250B and µRAM; Input and output dynamic response no added C

TRAN; 18% of 20 A rating load step of

3.5 A (10 A – 13.5 A); RHR = 80 k (Configured as in Figures 14–1a

and 14–1b

)

Figure 12–13 — V300B12C250B and µRAM; Input and output dynamic response CTRAN = 820 µF Electrolytic; 30% of load step of 6 A (10 A – 16 A); R

and 14–1b

)

HR = 80 k (Configured as in Figures14–1a

Maxi, Mini, Micro Design Guide Rev 4.9 vicorpower.com

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Apps. Eng. 800 927.9474 800 735.6200

Page 62

Design Guide & Applications Manual

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

12. Output Ripple Attenuator Module (MicroRAM)

Figure 12–14 — V48C5C100B and µRAM; Input and output ripple @ 50% (10 A) load CH1 = Vi; CH2 = Vo; Vi – Vo = 327 mV; RHR = 31 k (Configured as in Figures 12–1a and 12–1b)

Figure 12–15 — V48C5C100B and µRAM; Input and output dynamic response no added C

TRAN; 23% of 20 A rating load step

of 4.5 A (10 A – 14.5 A); RHR = 31 k (Configured as in Figures 12–1a

and 12–1b

)

Figure 12–16 — V48C5C100B and µRAM; Input and output dynamic response C of 7 A (10 A – 17 A); R

and 12–1b)

TRAN = 820 µF Electrolytic; 35% of load step

HR = 31 k (Configured as in Figures 12–1a

NOTES: The measurements in Figures 12–8 through 12–16 were taken with a µRAM2C21 and standard scope probes set at 20 MHz bandwidth scope setting.

The criteria for transient current capability was as follows: The transient load current step was incremented from 10 A to the peak value indicated, then stepped back to 10 A until the resulting output peak to peak measured ~ 40 mV.

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Apps. Eng. 800 927.9474 800 735.6200

Page 63

13. Recommended Soldering Methods, Lead Free Pins (RoHS)

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

OVERVIEW

he following chapters contain soldering information for

T the following Vicor product families; Maxi, Mini, Micro;

VE-200, VE-J00; VI BRICK

, and similar package filters and front-ends. This document is intended to provide guidance for making high-quality solder connections of RoHScompliant Vicor power modules to printed circuit boards. This application note applies to lead-free soldering of Vicor’s RoHS- compliant modules. The following provides an outline for appropriate soldering procedures and the evaluation of solder joints to ensure an optimal connection to the power module. Common soldering defects will be examined and direction will be provided for detecting and handling them. Vicor’s manufacturing facilities use the IPC-A-610 standards for establishing quality solder joints. It is recommended that manufacturing processes using Vicor modules refer to these same standards, which can be found, along with supporting documentation, at

www.ipc.org.

hether they are soldered by hand, by fountain, or by

w wave.

In examining a solder joint, be sure that there is no solder connecting one pad to another. This is known as a solder bridge and will be discussed later.

Design Guide & Applications Manual

ANALYSIS OF A GOOD SOLDER JOINT

The IPC-A-610 standard requires that solder fill at least 75% of the barrel to ensure a solid connection. Ideally, all connections should have a 100% fill. To accomplish this, the solder applied to both the barrel and the pin must exhibit a process known as wetting. Wetting occurs when liquid solder on a surface is heated to the point that it loses a significant amount of latent surface tension and evenly coats the surface via capillary action (both cohesion and adhesion).

During the soldering process wetting can be identified by an even coating of solder on the barrel and pin. In addition, coating the surface of barrel and pin, the solder will gather at the intersection of the two and produce a trailing fillet along each surface. Once wetting has occurred, then upon solidification it will bond appropriately to both components, producing a quality connection.

Figure 13–1 shows a side profile of a good solder joint with a power module. Notice that the solder forms a concave meniscus between pin and barrel. This is an example of a properly formed fillet and is evidence of good wetting during the soldering process. The joint between solder and pin as well as solder and pad should always exhibit a feathered edge. In Figure 13–1 it can also be seen that the solder covers a good deal of the surface area of both the pin and the pad. This is also evidence of good wetting. (Notice also that the solder joint is dull compared to leaded processing). This is evidence of good immobilization of the joint during cooling as well as good cleaning of the board prior to soldering. All soldering connections should exhibit similar characteristics regardless of

Figure 13–1 — Side profile of Maxi or Mini module’s RoHS solder joint.

SOLDERING PROCEDURES

Hand Soldering. Before soldering, make sure that the PCB is clean and free of debris, chemical residue, or liquid. It is not recommended that additional flux other than what is contained in the solder be used during soldering because it potentially leaves a residue that cannot be removed without potentially damaging or compromising the power module. Also, the presence of these residues on the modules may cause harm or improper operation.

The pins on Vicor modules are optimized to provide a lowresistance electrical connection. The final mounting scheme for any module should be designed to minimize any potential mechanical stress on the pins and solder joints. Modules with heat sinks or modules used in systems that are subject to shock or vibration should use standoffs to minimize stress on the pins. It is not recommended that discrete wires or connectors be soldered directly onto a module.

Also necessary for a good solder connection is pin protrusion from the PCB. It is not possible to create a good solder joint without some protrusion of module pins from the PCB. If the PCB is too thick to allow good pin protrusion, consider using Vicor module accessories such as sockets to allow proper mounting. Before soldering, the module should be mechanically affixed or immobilized with

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13. Recommended Soldering Methods, Lead Free Pins (RoHS)

respect to the PCB to ensure no movement during the soldering process. The standoffs can be used for this process. Vicor power modules contain two types of pins:

ower pins (which deliver the power to the load and are

p typically sized according to the rated output current) and

ignal pins (which typically carry very little current and are

s of a uniform size across a given product family). The larger the pin, the more soldering time required to form an adequate connection. In addition to the sizing of the pin, the time required to create a robust connection will vary depending on several parameters:

1. PCB Thickness. The thicker the printed circuit board,

the more heat it is able to dissipate, and will require more soldering time.

2. Copper Trace Area. Power pins require large copper

traces to minimize resistive power losses in carrying the power to the load. Since the copper tends to conduct heat well, the actual sizes of these copper traces directly affect the amount of time necessary to heat the PCB socket.

3. Copper Trace Thickness. As above, the thickness of the

copper trace is a function of output current of the module, and has a direct impact on the amount of soldering time. Typically, PCB copper thickness is specified in terms of weight per square foot, typically 2 oz. or 3 oz. copper for current-carrying planes.

4. Soldering Iron Power. A higher power soldering iron

can source more heat and thus take less time to heat a PCB trace. As a soldering iron is heating a point on the board, everything that is adjacent to this point is being heated as well, including the Vicor power module. A large copper trace, because it conducts heat very well, will exhibit less of a thermal gradient, and thus a low-power soldering iron will have to heat the whole trace to a higher temperature before the area close to the iron is hot enough to flow solder. Because the trace and board are both dissipating and conducting thermal energy, some irons may not have enough power to heat a trace to the temperature that will allow proper soldering.

5. Tip Temperature. Typical SAC-type solder melts at

419 – 491°F (215 – 225°C). Pb-free soldering requires a tip temperature of about 800°F. A higher tip temperature will bring the barrel and pin above the melting point of solder faster. However, a higher tip temperature may cause damage to the pad, printed circuit board, or module pin.

6. Type of Lead-free Solder. The actual melting point of the solder varies depending on the type of solder used and affects the necessary temperature of the pad and

in for flow. Vicor recommends SAC305 SnAgCu

p solder for use on Vicor power modules.

7. Tip Size. A larger tip will be able to heat a larger surface area, thus lowering soldering time.

Since there are so many factors that influence soldering time, listing actual times is difficult. In general, it is recommended that the joint be examined post-process to insure a quality soldering joint. If necessary, different parameters can then be varied in order to ensure a solid process. The soldering times listed in Table 13–1 can be used as a guideline for establishing more application and process specific parameters. Below are some recommendations for general practice:

1. Do not

run tip temperature above 810°F (430°C). This will greatly increase the risk of damaging the pads, traces, printed circuit board, or Vicor power module. Check with the printed circuit board manufacturer that the boards are RoHS capable and for any additional recommendations in regard to temperature.

2. Apply the soldering iron to one side of the pin and pad and apply the solder to the other, allowing the heat from the pin and pad to melt the solder. Do not apply solder to the soldering iron and subsequently attempt to transfer it to the pad and pin. Melting the solder by applying it directly to the soldering iron does not guarantee adequate wetting on the joint and is not considered good technique.

3. Do not apply excessive pressure with the soldering iron to the printed circuit board, barrel, or pad. This could result in breaking a trace, dislodging a barrel, or damaging the PCB, which becomes noticeably softer when heated.

4. Do not apply the soldering iron to a connection for an extended period of time or damage to the module could result. If the soldering times exceed the upper limit listed in Table 13–1, consider using a larger tip or a higher power soldering iron.

5. Make sure PCB pads and holes are clean before to soldering.

6. Solders with no-clean flux may be used to facilitate soldering.

7. Keep the tip of the soldering iron clean and free from resin. Apply a small amount of solder directly to the tip of the iron. This process is known as tinning.

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or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

Design Guide & Applications Manual

8. Be careful not to jar the module or PCB while the solder is cooling. This could result in a cold solder joint, a void in the barrel, or a cracked joint.

9. If it is necessary to re-solder a joint, remove all existing solder from the pad and pin before reapplying solder.

10. Use of a soldering gun is not recommended for soldering Vicor modules.

11. It is not recommended that Maxi / Mini / Micro module pins be trimmed under any circumstances.

As a procedural benchmark, given an 800°F (427ºC) temperature on a 60 W iron with a 3 mm tip, approximate times to solder a Vicor power module to a 0.062 (1,5 mm) thick PCB board with an appropriately sized copper trace would be in the range of Table 13–1.

Converter Family Pin Type

VE-200 / VE-J00 Signal 3 – 5 seconds VE-200 Power 5 – 8 seconds VE-J00 Power 4 – 7 seconds Maxi/ Mini / Micro Signal 3 – 5 seconds Maxi Power 5 – 8 seconds Mini Power 4 – 7 seconds Micro Power 3 – 5 seconds VI BRICK Input & Signal 3 – 5 seconds VI BRICK Power 4 – 7 seconds Also relevant for similar packaged accessory modules

Table 13–1 — Recommended pin soldering times for RoHS family modules

Soldering

Time (range)

Again, please note that soldering for significantly longer periods of time than those listed above could result in damage to the module. Table 13–1 should not be used without verifying that the times will produce a quality soldering joint as defined in the previous sections.

Wave Soldering. Vicor modules achieve an adequate solder connection on a wave-soldering machine with conveyor speeds from three to seven feet per minute. As with hand soldering, times and parameters vary with the properties of the PCB and copper traces. As a standard benchmark, the parameters below may be used. As with hand-soldered boards, the results should be examined to ensure a quality soldering joint and a sound process.

Wave Soldering Profile.

1. Bottom-side preheaters: Zone 1: 350°F (177°C),

Zone 2: 300°F (149°C), Zone 3: 675°F (357°C)

2. Top-side preheaters: 220 – 235°F (104 – 113°C)

3. Wave temperature: 510°F (266°C)

Preheating of the PCB is generally required for wave soldering operations to ensure adequate wetting of the solder to the PCB. The recommended temperature for PCB

opside is 203 – 248°F (95 – 120°C) prior to the molten

t wave. Thick, multilayer PCBs should be heated toward the

pper limit of this range, while simple two-layer PCBs

u should be heated to the lower limit. These parameters are consistent with generally accepted requirements for circuit-card assembly. The power module is often much more massive than other components mounted to the PCB. During wave solder preheating, the pins will dissipate much of their absorbed heat within the module; therefore, adjustments to preheaters alone will not improve module soldering significantly. A more effective way to improve the soldering of the module is to lower the conveyor speed and increase the dwell time in the molten wave. Approximately 5 seconds of exposure to the molten wave is required to achieve an acceptable solder joint for a Maxi / Mini / Micro power module. The VE-200 / VE-J00/

VE-HAM and VI BRICK

modules should solder in approxi-

mately 4 seconds of molten wave exposure.

Post Solder Cleaning. Vicor modules are not hermetically sealed and must not be exposed to liquid, including but not limited to cleaning solvents, aqueous washing solutions or pressurized sprays. Cleaning the backside of the PCB is acceptable provided no solvent contacts the body of the module.

When soldering, it is recommended that no-clean flux solder be used, as this will ensure that potentially corrosive mobile ions will not remain on, around, or under the module following the soldering process.

If the application requires the PCB to be subject to an aqueous wash after soldering, then it is recommended that Vicor module accessories such as through-hole or surface-mount sockets be used. These sockets should be mounted to the PCB, and the modules subsequently inserted following the aqueous washing sequence.

De-soldering Vicor Modules. Vicor modules should not be re-used after desoldering for the following reasons:

1. Most de-soldering procedures introduce damaging mechanical and thermal stresses to the module.

2. Devices or processes that may be capable of desoldering a Vicor module from a printed-circuit board without causing damage have not been qualified for use with Vicor modules.

For applications that require removal of a module with the intent of reuse, use Vicor socketing systems.

4. Wave type: 4.25 in (107,95 mm) standard laminar wave

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13. Recommended Soldering Methods, Lead Free Pins (RoHS)

Index of Common Soldering defects.

1. Solder Bridge. A short circuit between two electrically inadvertently forming a “bridge” or connection between the two points.

ecommended Solution. Use a smaller soldering tip,

or hold the tip at a different angle when soldering, so as to contact only one pad at a time.

2. Cold Solder. An incomplete or poor connection caused by either the barrel or the pin not being heated to the flow temperature of solder. A cold solder joint will typically exhibit a convex meniscus with possibly a dark spot around the barrel or pad. Also, a cold solder joint will not be shiny, but will typically have a “dirty” appearance.

CAUTION: A cold solder joint is not necessarily an open connection electrically, and cannot be diagnosed by a simple continuity check. A cold solder joint is frequently an electrically intermittent connection and is best diagnosed by way of visual inspection. A cold solder joint will likely become electrically open following a period of temperature cycling.

Recommended Solution. Increase soldering iron temperature, soldering time, or use a soldering iron with a higher output wattage if hand soldering. If wave soldering, lower conveyor speed or increase preheat temperature.

4. De-wetting. The solder initially appears to wet but then pulls back to expose the pad surface. More common in wave-soldering.

Recommended Solution. Make sure the PCB is clean prior to soldering.

5. Dry Joint. The solder has a dull gray appearance as opposed to a bright silver surface. The solder joint may have a mottled look as well, with jagged ridges. It is caused by the solder joint moving before it has completely cooled.

Recommended Solution. Immobilize the module with respect to the PCB to ensure that the solder joint cools properly.

6. Icicles. Jagged or conical extensions from solder fillet. These are caused by soldering with the temperature too low, or soldering to a highly heat absorbent surface.

Recommended Solution. Increase the soldering temperature, but not outside the recommended limits. If necessary, use a higher power soldering iron.

7. Pinholes. Small or large holes in surface of solder joint, most commonly occurring in wave solder systems.

Recommended Solution. Increase preheat or topside heater temperature, but not outside the recommended limits.

3. PC Board Damage. An intermittent or poor connection caused by damage to a trace, pad, or barrel. A damaged pad is best identified by a burn mark on the PCB, or a trace pad that moves when prodded with a mechanical object.

Recommended Solution. Lower the soldering iron temperature or the soldering time. If damage persists, use a lower power iron, or consult with the manufacturer of the PCB for recommended soldering guidelines.

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Design Guide & Applications Manual

References

Organizations

ww.ipc.org

Commercial

www.aimsolder.com

www.alphametals.com

www.kester.com

www.multicore-association.org

Maxi / Mini / Micro Standoff Kits for Solder Mounted Modules

Board Mounting Slotted Through-Hole Threaded

Thickness Options Baseplate Baseplate Baseplate

Nom. Mounting Pin Through-Hole Threaded Through-Hole Threaded Through-Hole

(Min/Max) Style Style Heat Sink Heat Sink Heat Sink Heat Sink Heat Sink

0.062"

(0.055"/0.071")

1,5 mm

(1,4 mm / 1,8 mm)

0.093

(0.084"/0.104")

2,4 mm

(2,1 mm / 2,6 mm)

In-Board F

On-Board G

In-Board G

Kit-18150 Kit-18151 Kit-18146 Kit-18147 Kit-18146

Bag-19126 Bag-19127 Bag-19122 Bag-19123 Bag-19122

Kit-18156 Kit-18157 Kit-18150 Kit-18152 Kit-18150

Bag-19132 Bag-19133 Bag-19126 Bag-19128 Bag-19126

Kit-18150 Kit-18151 Kit-18146 Kit-18147 Kit-18146

Bag-19126 Bag-19127 Bag-19122 Bag-19123 Bag-19122

Table 13–2 — Standoff Kits for solder mounted modules

Kits include six (6) standoffs and screws. Mini and Micro modules require a minimum of four (4) standoffs. Bags contain 100 standoffs only (#4-40 screws required).

VI BRICK®Standoff Kits

Standoffs Description Part No.

(includes M3 x 5 mm and M3 x 6 mm screws)

F-F Standoff

0.287” long

M-F Standoff

0.287” long

Bags contain 100 standoffs only (M3 screws required).

12 pc Kit for 0.125” PCB

12 pc Kit for 0.062” PCB

(includes M3 x 5 mm screws)

100 pc bag 34709

12 pc Kit

(includes M3 x 6 mm screws)

100 pc bag 34710

34717

34718

34719

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OVERVIEW

he following chapters contain soldering information for

T the following Vicor product families; Maxi, Mini, Micro;

VI-200, VI-J00; VI BRICK

, and similar package filters and front-ends. This document is intended to provide guidance in utilizing soldering practices to make high-quality connections of Vicor power modules to printed circuit boards. Some care will be taken to outline appropriate soldering procedures as well as the evaluation of solder joints in a manner that enables the customer to ensure that the end application has an optimal connection to the power module. Common soldering defects will be examined and direction will be provided for detecting and handling the common defects.

Vicor’s manufacturing facilities use the IPC-A-610C standards as a means of establishing quality solder joints. It is recommended that manufacturing processes using Vicor modules refer to these same standards, which can be found, along with supporting documentation, at

www.ipc.org.

14. Recommended Soldering Methods, Tin Lead Pins, and InMate Sockets

imilar characteristics regardless of whether they are

s soldered by hand or wave soldered.

Figure 14–1 — Side profile of a Mini module solder joint

ANALYSIS OF A GOOD SOLDER JOINT

The IPC-A-610C standard requires that solder fill at least 75% of the barrel in order to ensure a solid connection. Ideally, all connections should have a 100% fill. In order to accomplish this, the solder applied to both the barrel and the pin must exhibit a process known as wetting. Wetting occurs when liquid solder on a surface is heated to the point that it loses a significant amount of latent surface tension and evenly coats the surface via capillary action (both cohesion and adhesion).

During the soldering process wetting can be identified by an even coating of solder on the barrel and pin. In addition to coating the surface of barrel and pin, the solder will gather at the intersection of the two and produce a trailing fillet along each surface. Once wetting has occurred, then upon solidification it will bond appropriately to both components, producing a quality connection. Figure 14–1 shows a side profile of a good solder joint with a Mini power module. Notice that for both examples the solder forms a concave meniscus between pin and barrel. This is an example of a properly formed fillet and is evidence of good wetting during the soldering process. The joint between solder and pin as well as solder and pad should always exhibit a feathered edge. In Figure 14–1 it can also be seen that the solder covers a good deal of the surface area of both the pin and the pad. This is also evidence of good wetting. Notice also that the solder joint has a smooth surface with a silver color. This is evidence of good immobilization of the joint during cooling as well as good cleaning of the board prior to soldering. All soldering connections should exhibit

Figure 14–2 — Maxi / Mini output power pin and Sense pin

Figure 14–2 is a top view of the signal and power pin of a Maxi or Mini module properly soldered to a printed circuit board. Notice that both the joint and the area around the joint are clean and free from resin and solder residue. Also the pad and printed circuit board adjacent to the barrel are not burnt or discolored and are solidly attached to each other. In examining a solder joint, be sure that there is no solder connecting one pad to another. This is known as a solder bridge and will be discussed further along with other potential soldering defects.

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SOLDERING PROCEDURES

and Soldering. Before soldering, make sure that the

PCB is clean and free of debris, chemical residue, or liquid. It is not recommended that additional flux other than what is contained in the solder be used during soldering as it potentially leaves a residue that cannot be removed without potentially damaging or compromising the power module. Also, the presence of these residues themselves on the modules may cause harm or improper operation. The pins on Vicor modules are optimized in design for providing a low-resistance electrical connection. The final mounting scheme for any module should be designed so as to minimize any potential mechanical stress on the pins and solder joints. Modules with heat sinks or modules used in systems that are subject to shock or vibration should use standoffs to minimize stress on the pins. Tin / lead pins are specifically designed for soldering applications while gold pin options are specified for socketed applications (see SurfMate or InMate mounting systems). It is not recommended that discrete wires or connectors be soldered directly onto a module.

Before soldering, the module should be mechanically affixed or immobilized with respect to the PCB to ensure no movement during the soldering process. The standoffs can be used for this process.

Vicor power modules contain two types of pins: power pins (which deliver the power to the load and are typically sized according to the rated output current) and signal pins (which typically carry very little current and are of a uniform size across a given product family). The larger the pin, the more soldering time required to form an adequate connection. In addition to the sizing of the pin the time required to create a robust connection will vary depending on several parameters:

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

. Copper Trace Thickness. As above, the thickness of

Design Guide & Applications Manual

the copper trace is a function of output current of the module, and has a direct impact on the amount of soldering time. Typically, PCB copper thickness is specified in terms of weight per square foot, typically 2 oz. or 3 oz. copper for current-carrying planes.

4. Soldering Iron Power. A higher power soldering iron can source more heat and thus take less time to heat a PCB trace. When a soldering iron is heating a point on the board, everything that is adjacent to this point is being heated as well, including the Vicor power module. A large copper trace, because it conducts heat very well, will exhibit less of a thermal gradient and thus a low-power soldering iron will have to heat the whole trace to a higher temperature before the area close to the iron is hot enough to flow solder. Because the trace and board are both dissipating and conducting thermal energy, some irons may not have enough power to heat a trace to the temperature that will allow proper soldering.

5. Tip Temperature. Typical 63 / 37 solder melts at 392°F (200°C). A higher tip temperature will bring the barrel and pin above the melting point of solder faster. However, a higher tip temperature may cause damage to the pad, printed circuit board, or module pin.

6. Type of Solder. The actual melting point of the solder varies depending on the type of solder used and affects the necessary temperature of the pad and pin for flow. Vicor recommends 63 / 37 SnPb solder for use on Vicor power modules.

7. Tip Size. A larger tip will be able to heat a larger surface area, thus lowering soldering time.

1. PCB Thickness. The thicker the printed circuit board is, the more heat it is able to dissipate, and thus it will require more soldering time.

2. Copper Trace Area. Power pins require large copper traces to minimize resistive power losses in carrying the power to the load. Since the copper tends to conduct heat rather well, the actual size of these copper traces directly affect the amount of time necessary to heat the PCB socket.

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14. Recommended Soldering Methods, Tin Lead Pins, and InMate Sockets

Since there are so many factors that influence soldering time, listing actual times is difficult. In general, it is recommended that the joint be examined post-process to

nsure a quality soldering joint. If necessary, different

e parameters can then be varied in order to ensure a solid

rocess. The soldering times listed in Table 14–1 can be

p used as a guideline for establishing more application and process-specific parameters. Below are some recommendations for general practice:

1. Do not run tip temperature above 750°F (400°C) because it will greatly increase the risk of damaging the pads, traces, printed circuit board, or Vicor power module. Check with the printed circuit board manufacturer for any additional recommendations with regards to temperature.

3. Do not apply excessive pressure with the soldering iron to the printed circuit board, barrel, or pad. This could result in breaking a trace, dislodging a barrel or damaging the PCB, which becomes noticeably softer when heated.

4. Do not apply the soldering iron to a connection for an extended period of time or damage to the module could result. If the soldering times exceed the upper limit listed in Table 14–1, consider using a larger tip or a higher power soldering iron.

5. Make sure PCB pads and holes are clean prior to soldering.

6. Solders with no-clean flux may be used to facilitate soldering.

7. Keep the tip of the soldering iron clean and free from resin. Apply a small amount of solder directly to the tip of the iron. This process is known as tinning.

8. Be careful not to jar the module or PCB while the

solder is cooling. This could result in a cold solder joint, a void in the barrel, or a cracked joint.

9. If it is necessary to re-solder a joint, remove all

existing solder from the pad and pin prior to reapplying solder.

10. Use of a soldering gun is not

recommended for

soldering Vicor modules.

11. It is not

recommended that Maxi, Mini, Micro module

pins be trimmed under any circumstances.

12. The caps of the InMate socket are designed to repel solder. It is normal for this surface to be free of solder.

s a procedural benchmark, given a 750°F (400°C) tem-

A perature on a 60 W iron with a 0.19 in (3 mm) tip, approximate times to solder a Vicor power module to a

0.062 (1,5 mm) thick PCB board with an appropriately

sized copper trace would be in the range of Table 14–1.

Converter Family Pin Type

VI-200 / VI-J00 Signal 3 – 5 seconds VI-200 Power 5 – 8 seconds VI-J00 Power 4 – 7 seconds Maxi/ Mini / Micro Signal 3 – 5 seconds Maxi Power 5 – 8 seconds Mini Power 4 – 7 seconds Micro Power 3 – 5 seconds

Table 14–1 — Recommended pin soldering times for Vicor modules

Soldering

Time (range)

Again, please note that soldering for significantly longer periods of time than the time listed above could result in damage to the module. The time listed in Table 14–1 should not be used without verifying that the times will produce a quality soldering joint as defined in the previous sections.

Wave Soldering. Vicor modules achieve an adequate solder connection on a wave soldering machine with conveyor speeds from three to seven feet per minute. As with hand soldering, times and parameters vary with the properties of the PCB and copper traces. As a standard benchmark the parameters below may be used. As with hand-soldered boards, the results should be examined to ensure a quality soldering joint and a sound process.

Wave Soldering Profile.

1. Bottom-side preheaters: Zone 1: 650°F (343°C),

Zone 2: 750°F ( 398°C)

2. Top-side preheaters: 203 – 248°F (95 – 120°C)

3. Wave temperature: 500°F (260°C)

4. Wave type: 4.25 in (107,9 mm) standard laminar wave

Preheating of the PCB is generally required for wave soldering operations to ensure adequate wetting of the solder to the PCB. The recommended temperature for PCB topside is 203 – 248°F (95 – 120°C) prior to the molten wave. Thick, multilayer PCBs should be heated toward the upper limit of this range, while simple two-layer PCBs should be heated to the lower limit. These parameters are consistent with generally accepted requirements for circuit-card assembly.

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or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

Design Guide & Applications Manual

The power module is often much more massive than other components mounted to the PCB. During wave solder preheating, the pins will dissipate much of their

bsorbed heat within the module. Adjustments to pre-

a heaters alone, therefore, will not improve module

oldering significantly.

A more effective way to improve the soldering of the module is to lower the conveyor speed and increase the dwell time in the molten wave. Approximately 5 seconds of exposure to the molten wave is required to achieve an acceptable solder joint for a Maxi, Mini, or Micro power module.

Post Solder Cleaning. Vicor modules are not hermetically sealed and must not be exposed to liquid, including but not limited to cleaning solvents, aqueous washing solutions, or pressurized sprays. Cleaning the backside of the PCB is acceptable provided no solvent contacts the body of the module.

If the application requires the PCB to be subject to an aqueous wash after soldering, then it is recommended that Vicor module accessories such as through-hole or surface-mount sockets be used. These sockets should be mounted to the PCB and the modules subsequently inserted following the aqueous washing sequence.

De-soldering Vicor Modules. Vicor modules should not be re-used after desoldering for the following reasons:

Index of Common Soldering defects.

1. Solder Bridge. A short circuit between two electrically

unconnected points caused by a piece of solder inadvertently forming a “bridge” or connection between the two points.

Recommended Solution. Use a smaller soldering tip, or hold the tip at a different angle when soldering, so as to only contact one pad at a time.

2. Cold Solder. An incomplete or poor connection

caused by either the barrel or the pin not being heated to the flow temperature of solder. A cold solder joint will typically exhibit a convex meniscus with possibly a dark spot around the barrel or pad. Also a cold solder joint will not be shiny, but will typically have a “dirty”appearance.

CAUTION

: A cold solder joint is not necessarily an open connection electrically, and cannot be diagnosed by a simple continuity check. A cold solder joint is frequently an electrically intermittent connection and is best diagnosed by visual inspection. A cold solder joint will likely become electrically open following a period of temperature cycling.

1. Most de-soldering procedures introduce damaging mechanical and thermal stresses to the module.

2. Devices or processes that may be capable of de-soldering a Vicor module from a printed circuit board without causing damage have not been qualified for use with Vicor modules. For applications that require removal of a module with the intent of reuse, use Vicor socketing systems.

3. PC Board Damage. An intermittent or poor connection caused by damage to a trace, pad, or barrel. A damaged pad is best identified by a burn mark on the PCB, or a trace of pad that moves when prodded with a mechanical object.

Recommended Solution. Lower the soldering iron temperature or the soldering time. If damage persists use a lower power iron, or consult with the manufacturer of the PCB for recommended soldering guidelines.

4. De-wetting. The solder initially appears to wet but then pulls back to expose the pad surface, more common in wave soldering.

Recommended Solution. Make sure the PCB is clean prior to soldering.

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14. Recommended Soldering Methods, Tin Lead Pins, and InMate Sockets

5. Dry Joint. The solder has a dull gray appearance as opposed to a bright silver surface. The solder joint may have a mottled look as well, with jagged ridges.

t is caused by the solder joint moving before

I completely cooled.

7. Pinholes. Small or large holes in surface of solder joint, most commonly occurring in wave-solder systems.

Recommended Solution. Increase preheat or topside heater temperature, but not outside the recommended limits.

Recommended Solution. Immobilize the module with respect to the PCB to ensure that the solder joint cools properly.

References

6. Icicles. Jagged or conical extensions from solder fillet. These are caused by soldering with the temperature too low, or soldering to a highly heat-absorbent surface.

Recommended Solution. Increase the soldering temperature, but not outside the recommended limits. If necessary, use a higher power soldering iron.

Organizations

www.ipc.org

Commercial

www.aimsolder.com

www.alphametals.com

www.kester.com

www.multicore-association.org

Maxi / Mini / Micro Standoff Kits for Solder Mounted Modules*

Board Mounting Slotted Through-Hole Threaded

Thickness Options Baseplate Baseplate Baseplate

Nom. Mounting Pin Through-Hole Threaded Through-Hole Threaded Through-Hole

(Min/Max) Style Style Heat Sink Heat Sink Heat Sink Heat Sink Heat Sink

0.062"

(0.055"/ 0.071")

(1,5 mm)

(1,4 mm / 1,8 mm)

0.093

(0.084"/ 0.104")

2,4 mm

(2,1 mm / 2,6 mm)

In-Board

On-Board L

In-Board L

Short

Tin/Lead

Kit-18150 Kit-18151 Kit-18146 Kit-18147 Kit-18146

Bag-19126 Bag-19127 Bag-19122 Bag-19123 Bag-19122

Kit-18156 Kit-18157 Kit-18150 Kit-18152 Kit-18150

Bag-19132 Bag-19133 Bag-19126 Bag-19128 Bag-19126

Kit-18150 Kit-18151 Kit-18146 Kit-18147 Kit-18146

Bag-19126 Bag-19127 Bag-19122 Bag-19123 Bag-19122

Table 14–2 — Standoff kits for solder mounted modules

* Kits include six (6) standoffs and screws. Mini and Micro modules require a minimum of four (4) standoffs.

100 piece bags contain standoffs only (#4-40 screws required).

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Page 73

15. Surface Mount Socketing System (SurfMate)

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

Design Guide & Applications Manual

SurfMate is a surface-mount connector system for use with pin-compatible Maxi, Mini, Micro Family converters and input / front-end modules. For the first time, circuit-

oard designers and assemblers have the ability to surface

b mount high-density DC-DC converters having current

atings up to 50 A. (Table 15–1)

SurfMate utilizes a pair of surface-mounted headers that contain sockets to accept the input and output pins of the module. (Table 15–2) The SurfMate header assembly is compatible with any thickness PC board, does not increase the module mounting height above the board, and is available for all three standard module size: Maxi, Mini, and Micro (full, half, and quarter bricks).

SurfMates are available packaged in standard recyclable JEDEC-style trays for use with automated pick-and-place equipment and are compatible with standard reflow solder operations. After reflow, the modules are simply inserted into the SurfMates. Any secondary soldering operation used for through-hole sockets or pins can now be entirely eliminated —reducing manufacturing time and eliminating dual processes.

This unique interconnect scheme combines the inherent flexibility of component power designs with the manufacturing efficiency of surface-mount assembly.

PRINTED CIRCUIT BOARD DESIGN AND SOLDER GUIDELINES FOR THE SURFMATE SOCKETING SYSTEM

Recommended PCB layout drawings for SurfMates are provided on the Vicor website. All unspecified PCB dimensional tolerances comply with ANSI/IPC-D-300 for Class “B” boards. DXF versions of the PCB outlines are available in the Accesorries section of the Vicor website.

Recommended PCB Construction. The SurfMate system is capable of very high current-carrying capacity. We therefore recommend a multilayer PCB with 3-ounce copper and internal power and ground planes. Consult the drawings for the recommended size and quantity of via holes for carrying current to the internal planes.

Solder Mask and Pad. Two solder mask keep-out areas are recommended. The larger area encompasses the complete pad area at either end. It ensures the proper height of the 3-ounce solder pads to the surrounding laminate. This provides for the optimum gap between the SurfMate and the PCB 0.0042" ±0.0004" (0,106 mm ±0,010 mm), minimizing the solder paste thickness required for quality solder joints. Without this solder mask keep-out area, the gap may widen, (see “Flush-Mounted Pads”), requiring thicker solder paste to fill the larger gap.

The smaller solder mask keep-out areas are circular, and are located on each pad, for the solder joint between the PCB and the SurfMate. The remainder of the pad has a

overing of solder mask. The solder paste is dispensed in

c a rectangular area covering the soldering area and part of

he solder mask area. During soldering, the paste will

t migrate away from the solder mask area to the soldering area, providing ample volume for quality solder joints.

Each pad features a non-plated through hole in the center of the pad to provide a venting function. It is normal for the solder joint to have a slight void centered on this through hole.

Solder Paste. Solder paste thickness requirements will vary depending on whether the board pads are flush or elevated from the laminate.

Elevated Pads (preferred). The ideal height for elevated pads is 0.0042"( 0,106 mm) ±10%. This can be achieved by using a 3-ounce copper surface layer. With this height, a minimum solder paste thickness of 0.006" should be used. Thicker stencils of between 0.008" (0,203 mm) and

0.012" (0,305 mm) are preferred.

Flush-Mounted Pads. For boards with flush-mounted pads a minimum of 0.010" (0,254 mm) solder paste should be used. Preferred thickness is between 0.012" (0,305 mm) and 0.016" (0,406 mm).

Placement. SurfMate locating pins will engage in the corresponding PCB holes with a light push of the SurfMate into the solder paste. The SurfMate should not be taped or adhered in place. The surface tension of the solder during reflow will center the SurfMate parts on the PCB, resulting in accurate positioning.

Equipment and Solder. Soldering of SurfMates should be done using either an infrared or convection oven reflow process. Solder type Sn63Pb37, or equivalent, with a eutectic temperature of 361°F (183°C) should be used. Higher temperature solder is not

recommended.

Standoffs. Mounting standoffs are required for SurfMate applications. The location for standoff holes is shown on the PCB layout. A selection chart of recommended standoff kits is provided in this section.

Module Pins. SurfMates must be used with modules with the “S” or “F” pin style.

Module Insertion / Extraction. Sockets and modules are rated for up to 5 insertions and extractions before requiring replacement. When installing a module, lightly place it into position so that all pins are properly aligned over each socket. Then apply even pressure by uniformly tightening each of the mounting screws through the mounting slots on the baseplate into the pcb mounted standoffs. For

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or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

15. Surface Mount Socketing System (SurfMate)

module removal, Vicor highly recommends the use of our Module Exchange Tool in order to ensure that the sockets

Removing the module at an angle should be avoided as this can damage the sockets.

are not damaged during the module removal process.

SurfMate: Surface Mount Sockets

Full Brick (Maxi) Half Brick (Mini) Quarter Brick (Micro)

Board Mounting

Thickness Style Style

All

Surface

mount

Input Output 5 Sets Input Output 5 Sets Input Output 5 Sets

22100 22101 16017 22100 22102 16021 22103 22104 16025 S, F

1. 2. 3.

Parameter Specification Value Reference

Compatibility F Short RoHS pins

Module pin style S Short ModuMate pins

Mechanical

Contact normal force 100 grams EOL min. GR-1217-CORE, R5-23

Number of mating cycles 5 max.

(Note4)

Module engagement force 32 lbs per connector set max. GR-1217-CORE, R5-31,32 Module disengagement force 32 lbs per connector set max. GR-1217-CORE, R5-31,32

Electrical

Current rating 50 A Maxi

(Note1)

, Mini; 25 A Micro Gold plating standards, and accepted

(Based on 248°F (120°C) max. socket temp. industry standards such as

& 86°F (30°C) max temperature rise of contact) IICIT, EIA, Bellcore guidelines

Low level contact resistance

0.080" (2,03 mm) dia socket (LLCR) Low level contact resistance

0.150" (3,81 mm) dia socket (LLCR) Low level contact resistance

0.180" (4,57 mm) dia sockets (LLCR)

Thermal

Max socket temperature temperature for gold plating

400 µΩ max. GR-1217-CORE, 6.2.1

300 µΩ max. GR-1217-CORE, 6.2.1

200 µΩ max. GR-1217-CORE, 6.2.1

248°F (120°C) max.

Temperature rise 86°F (30°C) max.

Environmental SurfMate products are tested in random vibration environments to best simulate the broad Shock and vibration spectrum of frequencies and amplitudes that may be encountered in typical applications.

Actual system resonant frequencies will depend on PCB construction and mounting details. For critical, or unusual, shock and vibration environments, the performance of the system should be independently verified.

Table 15–1 — SurfMate Specifications and Materials

Exception to GR-1217-CORE

which specifies 25 mating cycle

Max continuous use

GR-1217-CORE

EIA-364-70A

(Note2)

(Note3)

(Note1)

For 80 A operation with Maxi, contact Applications Engineering.

(Note2)

GR-1217-CORE issue 1, November 1995 Generic requirements for separable electrical connectors used in telecommunications hardware. A module of NEBSFR, FR-2063

(Note3)

ANSI/EIA-364 American National Standards Institute / Electronic Industries Association (Electronic Components, Assemblies & Materials Association)

(Note4)

The module and socket must be replaced after 5 mating cycles.

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15. Surface Mount Socketing System (SurfMate)

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

Design Guide & Applications Manual

Materials Ratings

Headers

Material: Vectra E150i LCP Liquid Crystal Polymer Flammability UL94 V-0/5VA Thermal stability (short term) 500°F (260°C) Thermal stability (long term) 392°F (200°C)

Solder Cap

Material 260 cartridge brass (70 Cu, 30 Zn)

Plating

Sockets

Material Brush Wellman Alloy #25 C17200 deep draw quality or equiv. 0.010" thick

Plating

100 µ in. min. Cu, followed by 50 to 100 µ in. min. low stress sulfamate-based electrolytic nickel, followed by 20 µ in. min. soft gold

Woods nickel strike followed by 50 µ in. min. low stress sulfamate-based electrolytic nickel, followed by 20 µ in. min. hard gold, followed by 10 µ in. min. soft gold

Table 15–2 — Material properties of SurfMate components

SurfMates

Figure 15–1 — SurfMates; Five pair sets Figure 15–2 — SurfMates; Individual part numbers

Package Maxi Mini Micro Notes

Five pair sets 16017 16021 16025 Inputs and outputs for five modules

Individual part numbers

Input 22100 22100 22103 Sold only in multiples of 35 Maxi, Mini, or 40 Micro.

Output 22101 22102 22104

Shipped in JEDEC trays

Table 15–3 — SurfMates: Part numbering and packaging

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or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

15. Surface Mount Socketing System (SurfMate)

Module Exchange Tool

Used in facilitating the proper extraction of modules from InMate or SurfMate sockets.

Removal without using the Exchange Tool may cause damage to the sockets.

Description Part Number

Maxi Exchange Tool 22827 Mini Exchange Tool 22828 Micro Exchange Tool 22829

22827

22829

22828

Standoff Kits for SurfMate Mounted Modules

Figure 15–3 — Slotted baseplate; Height above board with standoff Figure 15–4 — Though-hole or threaded baseplate; Height above

board with standoff

Heat Sinks Module Kit # 100 Piece Kit

Slotted Baseplate

Through-hole 20178 20188

Threaded 20179 20189

Through-hole Baseplate

Through-hole 20176 20186

Threaded 20177 20187

No heat sink 20184 20186

Threaded Baseplate

Through-hole 20176 20186

Threaded N/A N/A

No heat sink 20184 20186

Table 15–4 — Standoff kits for SurfMate mounted modules: Part numbering and packaging; Module kits contain enough standoffs and screws for one module. 100 piece kits contain standoffs only.

Standoff Kits for SurfMate Mounted Modules*

Board Mounting Slotted Through-Hole Threaded

Thickness Options Baseplate Baseplate Baseplate

Nom. Mounting Through-Hole Threaded Through-Hole Threaded Through-Hole

(Min/Max) Style Heat Sink Heat Sink Heat Sink Heat Sink Heat Sink

All

* Kits include six (6) standoffs and screws. Mini and Micro modules require a minimum of four (4) standoffs.

Bags of one hundred (100) do not include screws; #4-40 thread hardware required.

Surface

Mount

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Kit-20178 Kit-20179 Kit-20176 Kit-20177 Kit-20176

Bag-20188 Bag-20189 Bag-20186 Bag-20187 Bag-20186

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Page 77

16. Through-hole Socket Mount System (InMate)

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

Design Guide & Applications Manual

InMates are an innovative solution for through-hole socket requirements. Consisting of individual plastic carriers for the input and the output, each contains an array of sockets

or either a full, half or quarter-brick sized module. The

f sockets are factory loaded into the carrier, which holds

hem rigidly in place throughout the assembly and soldering

t process. The carriers are later removed, leaving the sockets accurately positioned.

Designed for use with pin-compatible Maxi, Mini, and Micro Family converters, InMates are available for a wide range of PCB sizes and mounting styles. PCB thicknesses can range from 0.055"(1,39 mm) to 0.1375"(3,49 mm).

Insert



Sockets also allow for mounting modules either inboard, with a cutout in the PCB for the module, to minimize the height above the board, or onboard. InMates are compati-

le with the ModuMate or RoHS pin style.

InMates are available in standard recyclable JEDEC style trays for use with automated pick-and-place equipment and are compatible with most standard wave or hand solder operations. The sockets are soldered into the board as part of the PCB assembly process. The module can then be plugged into place at anytime later.

NOTE: Please refer to

Section 13 of the design guide

for the InMate soldering procedure.

Figure 16–1

Solder



Remove Carrier

Insert Module

— InMate carrier / socket assembly and soldering process



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or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

InMate: Through-hole Sockets

16. Through-hole Socket Mount System (InMate)

1. 4.

Board Thickness Full Brick (Maxi) Half Brick (Mini) Quarter Brick (Micro)

Norm. Mounting

(Min. / Max.) Style Style

.062"

(0.055"/ 0.071")

1,5 mm

,4 mm / 1,8 mm)

0.093

.084"/ 0.104")

2,4 mm

(2,1 mm / 2,6 mm)

.125"

.1125"/0.1375")

(

3,1 mm

(2,8 mm / 3,5 mm)

Table 16–1 — Guide to InMate selection

1. Select Board Thickness. Nominal 0.062"

0.125"

(3,1 mm)

2. Select Mounting Style. Inboard requires a PCB cutout for the “belly” of the module. See dotted lines in PCB drawing links on Page 80 for cut out area.

3. Identify Module Type.

Full brick (Maxi), half brick (Mini) or

2. 3.

Input Output 5 Sets Input Output 5 Sets Input Output 5 Sets

Inboard 18374 18382 18362 18374 18384 18366 18376 18386 18370 S or F

Onboard 18378 18388 18364 18378 18390 18368 18380 18392 18372 N or G

Inboard 18375 18383 18363 18375 18385 18367 18377 18387 18371 S or F

Onboard 18379 18389 18365 18379 18391 18369 18381 18393 18373 N or G

Onb oard 21539 21543 21510 21539 21544 21511 21540 21545 21512 N or G

4. Select the Ordering Part Number.

(1,5 mm)

, 0.093"

(2,4 mm)

Order packages of five input / output sets or in higher quantities order input and output InMates separately. For individual input or output InMates, minimum orders of 35 for Maxi or Mini and 40 for Micro apply.

5. Verify Correct Pin Style for the Module. For predefined parts, “S” or “F”= short ModuMate and “N” or “G”= long ModuMate

See Table 16–4 for standoff recommendations.

quarter brick (Micro).

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16. Through-hole Socket Mount System (InMate)

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

Design Guide & Applications Manual

Parameter Specification Value Reference

Compatibility F = short Au plated Short RoHS pins

Module pin styles

Mechanical

Contact normal force 100 grams EOL min. GR-1217-CORE, R5-23

Number of mating cycles 5 max.

Module engagement force 32 lbs per connector max. GR-1217-CORE, R5-31,32 Module disengagement force 32 lbs per connector max. GR-1217-CORE, R5-31,32

Electrical

Current rating for output pin sockets

50 A Maxi

(Based on 248°F (120°C) max socket temp. & accepted industry standards

86°F (30°C) max temperature rise of contact) such as IICIT, EIA, Bellcore guidelines

Low level contact resistance

0.080" (2,03 mm) dia socket (LLCR) 400 µΩ max. GR-1217-CORE, 6.2.1 Low level contact resistance

0.150" (3,81 mm) dia socket (LLCR) 300 µΩ max. GR-1217-CORE, 6.2.1 Low level contact resistance

0.180" (4,57 mm) dia sockets (LLCR) 200 µΩ max. GR-1217-CORE, 6.2.1

Thermal

Max socket temperature

Temperature rise

Environmental InMate products are tested in random vibration environments to best simulate the broad spectrum

Shock and vibration of frequencies and amplitudes that may be encountered in typical applications. Actual system

resonant frequencies will depend on PCB construction and mounting details. For critical, or unusual, shock and vibration environments, the performance of the system should be independently verified.

Table 16–2 — InMate specifications and materials

S = short Au plated Short ModuMate pins G = long Au plated Long RoHS pins

N = long Au plated Long ModuMate pins

(Note4)

Exception to GR-1217-CORE

which specifies 25 mating cycle

(Note1)

/ 50 A Mini / 25 A Micro Gold plating standards, and

248°F (120°C) max.

86°F (30°C) max.

EIA-364-70A

(Note2)

Max continuous use

temperature for gold plating

GR-1217-CORE

(Note3)

Materials Ratings

Headers

Material: RytonTMR–7 PPS, 65% glass fiber and mineral filled compound Poly-Phenylene Sulfide Flammability UL94 V-0/5VA Thermal stability (short term) 500°F (260°C) Thermal stability (long term) 392°F (200°C)

Solder Cap

Material Plating Clear passivate to repel solder

Sockets Brush Wellman Alloy #25

Material C17200 deep draw quality or equiv. 0.010" thick

Woods nickel strike followed by 50 µ in. min. low stress

Plating

sulfamate-based electrolytic nickel, followed by

20 µ in min hard gold followed by 10 µ in. min. soft gold

Table 16–3 — Material properties of InMate components

(Note1)

For 80 A operation with Maxi, contact Applications Engineering.

(Note2)

GR-1217-CORE issue 1, November 1995 Generic requirements for separable electrical connectors used in telecommunications hardware. A module of NEBSFR, FR-2063

(1)

For 80 A operation with Maxi, contact Applications Engineering.

(Note3)

ANSI/EIA-364 American National Standards Institute / Electronic Industries Association (Electronic Components, Assemblies & Materials Association)

(Note4)

The module and socket must be replaced after 5 mating cycles.

305 stainless steel

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Design Guide & Applications Manual

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

16. Through-hole Socket Mount System (InMate)

Standoff Kits for InMate Mounted Modules*

Board Thickness Slotted Baseplate Through-Hole Baseplate Threaded Baseplate

Nom. Mounting Through-Hole Threaded Through-Hole Threaded Through-Hole

(Min. / Max.) Style Heat Sink Heat Sink Heat Sink Heat Sink Heat Sink

0.062"

0.055"/ 0.071")

(

,5 mm

(1,4 mm /1,8 mm)

0.093"

0.084"/ 0.104")

(

,4 mm

(2,1 mm /2,6 mm)

Inboard

Onboard

Inboard

Onboard

Kit-18153 Kit-18154 Kit-18148 Kit-18149 Kit-18148

Bag-19129 Bag-19130 Bag-19124 Bag-19125 Bag-19124

Kit-18158 Kit-18159 Kit-18153 Kit-18155 Kit-18153

Bag-19134 Bag-19135 Bag-19129 Bag-19131 Bag-19129

Kit-18153 Kit-18154 Kit-18148 Kit-18149 Kit-18148

Bag-19129 Bag-19130 Bag-19124 Bag-19125 Bag-19124

Kit-18156 Kit-18157 Kit-18150 Kit-18152 Kit-18150

Bag-19132 Bag-19133 Bag-19126 Bag-19128 Bag-19126

0.125"

.113"/ 0.138"

(

,1 mm

(2,8 mm /3,5 mm)

)

Onb oard

Kit - 24054 Kit-18157 Kit-24056 Kit - 18152 Kit- 24056

Bag-19132 Bag-19133 Bag -19126 Bag - 19128 Bag-19126

Table 16–4 — InMate standoff recommendations

* Kits include six (6) standoffs and screws. Mini and Micro modules require a minimum of four (4) standoffs.

Bags of one hundred (100) do not include screws; #4-40 thread hardware required.

References

InMate PCB layout drawing for Maxi Module

http://asp.vicorpower.com/cadUtil/display_cad.asp?pn=18400&ct=PDF

InMate PCB layout drawing for Mini Module

http://asp.vicorpower.com/cadUtil/display_cad.asp?pn=18399&ct=PDF

InMate PCB layout drawing for Micro Module

http://asp.vicorpower.com/cadUtil/display_cad.asp?pn=18398&ct=PDF

InMate and Socket outline drawing for Inboard Maxi Modules

http://asp.vicorpower.com/cadUtil/display_cad.asp?pn=18483-XX&ct=PDF

InMate and Socket outline drawing for Inboard Mini Modules

http://asp.vicorpower.com/cadUtil/display_cad.asp?pn=18482-XX&ct=PDF

InMate and Socket outline drawing for Inboard Micro Modules

http://asp.vicorpower.com/cadUtil/display_cad.asp?pn=18481-XX&ct=PDF

InMate and Socket outline drawing for Onboard Maxi Modules

http://asp.vicorpower.com/cadUtil/display_cad.asp?pn=18480-XX&ct=PDF

InMate and Socket outline drawing for Onboard Mini Modules

http://asp.vicorpower.com/cadUtil/display_cad.asp?pn=20030-XX&ct=PDF

InMate and Socket outline drawing for Onboard Micro Modules

http://vdac2.vicr.com/cadUtil/display_cad.asp?pn=20029-XX&ct=PDF

Module Exchange Tool

Used in facilitating the proper extraction of modules from InMate or SurfMate sockets.

Removal without using the Exchange Tool may cause damage to the sockets.

Description Part Number

Maxi Exchange Tool 22827 Mini Exchange Tool 22828 Micro Exchange Tool 22829

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22827

22829

22828

Page 81

17. Glossary of Technical Terms

or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

Design Guide & Applications Manual

AC-OK Signal. The signal used to indicate the loss of AC input voltage from the 115 / 230 V line.

ltitude Testing. Generally performed to determine the

proper functionality of equipment in airplanes and other flying objects. MIL-STD-810.

Ambient Temperature. The temperature of the environment, usually the still air in the immediate proximity of the power supply.

Apparent Power. A value of power for AC circuits that is calculated as the product of rms current times rms voltage, without taking power factor into account.

Bandwidth. A range of frequencies over which a certain phenomenon is to be considered.

Baseplate. All modular products have an aluminum mounting base at which Vicor specifies operating temperatures and which should be affixed to a thermally conductive surface for cooling.

Bellcore Specification. A telecommunications industry standard developed by Bellcore.

Bipolar Transistor. A transistor that operates by the action of minority carriers across a PN junction; and is a current controlled device as opposed to a voltage controlled device.

Bleeder Resistor. A resistor added to a circuit for the purpose of providing a small current drain, to assure discharge of capacitors.

Bobbin. A device upon which the windings of a transformer or inductor are wound, it provides a form for the coil and insulates the windings from the core.

Booster Converter. A “slave” module in a Driver / Booster combination, where the Driver is the master. Several Boosters can be paralleled with a Driver module for higher output power.

Breakdown Voltage. A voltage level at which dielectric insulation fails by excessive leakage current or arcing. In reference to power supplies the breakdown voltage is the maximum AC or DC voltage that can be applied from input to output and / or chassis.

Bridge Converter. A DC-DC converter topology (configuration) employing two or four active switching components in a bridge configuration across a power transformer.

Bridge Rectifier. A full wave rectifier circuit employing four rectifiers in a bridge configuration.

ritish Telecom Standards. A telecommunications

industry standard developed by the British PTT authorities.

Brownout. A reduction of the AC mains distribution voltage, usually caused deliberately by the utility company to reduce power consumption when demand exceeds generation or distribution capacity.

Burn-In. Operating a newly manufactured power supply, usually at rated load, for a period of time in order to force component infant mortality failures or other latent defects.

Capacitive Coupling. Coupling of a signal between two circuits, due to discrete or parasitic capacitance between the circuits.

Center Tap. An electrical connection made at the center of a transformer or inductor winding, usually so as to result in an equal number of turns on either side of the tap.

Centralized Power Architecture (CPA). One of the oldest power systems architectures, generates all system voltages at a central location and distributes them to load locations via distribution buses. This can be effective if the voltages are high and the currents low or if the distances between the power supply and the loads are small.

C-Grade. Industry standard where the operating temperature of a device does not drop below –20°C.

Chassis Mount Configuration. A configuration where the modules or AC front ends are mounted directly to the chassis.

Common-Mode Noise. Noise present equally on two conductors with respect to some reference point; often used specifically to refer to noise present on both the hot and neutral AC lines with respect to ground.

ComPAC. A Vicor DC input power supply that provides EMC filtering and transient suppression for industrial, military and telecommunications markets.

Constant Current Power Supply. A power supply designed to regulate output current for changes in line, load, ambient temperature and drift resulting from time.

Constant Voltage Power Supply. A power supply designed to regulate output voltage for changes in line, load, ambient temperature and drift resulting from time.

Control Circuit. A circuit in a closed-loop system, typically containing an error amplifier, that controls the operation of the system to achieve regulation.

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or Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies

17. Glossary of Technical Terms

Converter. An electrical circuit that accepts a DC input and generates a DC output of a different voltage usually achieved by high frequency switching action employing inductive and capacitive filter elements.

rest Factor. In an AC circuit, the mathematical ratio of

the peak to rms values of a waveform. Crest factor is sometimes used for describing the current stress in AC mains supply wires, since for a given amount of power transferred, the rms value, and hence the losses, become greater with increasing peak values. Crest factor gives essentially the same information as power factor, and is being replaced by power factor in power supply technology.

Cross Regulation. The effect of a load change on one output to the regulation of another output. It usually only applies to non postregulated (quasi) outputs.

Crowbar. An overvoltage protection method that shorts the power supply output to ground in order to protect the load when an overvoltage fault is detected.

CSA. Canadian Standards Association. Defines the standards and safety requirements for power components.

Current Limiting. An overload protection circuit that limits the maximum output current of a power supply in order to protect the load and / or the power supply.

power sources with a single bulk supply that is converted to the end-use voltages by DC-DC converters located at the point of need. The growth of this design technique is demonstrated by the size of the DC-DC converter market. Distributed power can reduce the system size, reduce the system weight, provide better operation with battery power, and deliver more efficient sub-system isolation and redundancy.

Drift. The change in an output voltage, after a warm-up period, as a function of time when all other variables such as line, load, and operating temperature are held constant.

Driver Module. The controlling module in a standalone or Driver / Booster configuration. The Driver module contains all the control circuitry.

Dropout. The lower limit of the AC input voltage where the power supply just begins to experience insufficient input to maintain regulation. The dropout voltage for linears is largely line dependent, whereas for most switchers it is largely load dependent, and to a smaller degree line dependent.

Dynamic Load Regulation. The delta in output voltage when the output load is rapidly changed.

Current Mode. A control method for switch-mode converters where the converter adjusts its regulating pulsewidth in response to measured output current and output voltage, using a dual loop control circuit.

Current Monitor. An analog power supply signal that is linearly proportional to output current flow.

DC-OK Signal. Signal used to monitor the status of the DC output.

Derating. A reduction in an operating specification to improve reliability. For power supplies it is usually a specified reduction in output power to facilitate operation at higher temperatures.

Design Life. The expected lifetime of a power supply during which it will operate to its published specifications.

Differential-Mode Noise. Noise that is measured between two lines with respect to a common reference point excluding common-mode noise. The resultant measurement is the difference of the noise components of the two lines. The noise between the DC output and DC return is usually measured in power supplies.

Efficiency. The ratio of total output power to input power expressed as a percentage.

Electronic Load. An electronic device designed to provide a load to the outputs of a power supply, usually capable of dynamic loading, and frequently programmable or computer controlled.

EMC. Electromagnetic Compatibility. Relating to compliance with electromagnetic emissions and susceptibility standards.

EMI. Electromagnetic Interference. The generation of unwanted noise during the operation of a power supply or other electrical or electronic equipment.

ESR. Equivalent Series Resistance. The value of resistance in series with an ideal capacitor that duplicates the performance characteristics of a real capacitor.

Distributed Power Architecture (DPA). A power distribution architecture that replaces multiple central

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Factorized Power Architecture (FPA). A power distribution architecture that is inherently more granular and leverages an allocation of the DC-DC converter functions consistent with efficient power distribution principles. An optimal power distribution architecture should efficiently support demanding low voltage, high current loads. FPA is a higher level power architecture that offers dramatic improvements in onboard power distribution systems, in performance, reliability and economy.

Fault Tolerant Configuration. A method of parallel operation, using output Oring diodes, in which the failure of a single supply (module) will not result in a loss of power. The total current of the parallel system must not exceed the load requirements to a point where the failure of a single unit will not result in a system overload.

FET. Field Effect Transistor. A majority carrier-voltage controlled transistor.

FinMod. A flangeless /finned packaging option available on Vicor’s VI-/MI-Family converters and accessory modules.

FlatPAC. A Vicor AC-DC switcher available with one, two or three outputs, with total power rating from 50 – 600 W.

Floating Output. An output of a power supply that is not connected or referenced to any other output, usually denoting full galvanic isolation. Floating outputs can generally be used as either positive or negative outputs. Non floating outputs share a common return line and are hence DC referenced to one another.

Foldback Current Limiting. A type of protection circuit where the output current decreases as the overload increases. The output current reaches a minimum as the load approaches a short circuit condition.

Forward Converter. A switching power supply in which the energy is transferred from the input to the output during the “on” time of the primary switching device.

GATE IN. The GATE IN pin of the module may be used to turn the module on or off. When GATE IN is pulled low, the module is turned off. When GATE IN is floating (open collector) the module is turned on. The open circuit voltage of the GATE IN pin is less than 10 V, referenced to –Vin. A GATE OUT / GATE IN connection is necessary to run Driver / Booster configurations.

GATE OUT. The GATE OUT pin is the clock pulse of the converter. It is used to synchronize Booster modules to a Driver module for high power arrays.

Ground. An electrical connection to earth or some other conductor that is connected to earth. Sometimes the term “ground” is used in place of “common,” but such usage is not correct unless the connection is also connected to earth.

Ground Loop. An unintentionally induced feedback loop caused by two or more circuits sharing a common electrical ground.

Haversine. A waveform that is sinusoidal in nature, but consists of a portion of a sine wave superimposed on another waveform. The input current waveform to a typical offline power supply has the form of a haversine.

Headroom. Used in conjunction with series pass regulators, headroom is the difference between the input and output voltages.

Heat Sink. A medium of high thermal mass that can absorb (sink) heat indefinitely with negligible change in temperature. Heat sinks are not necessarily needed with Vicor modules, and their use is highly dependent on the individual application, power and ambient temperature.

High Line Input. The maximum steady-state input voltage on the input pin.

Hipot. Abbreviation for high potential, and generally refers to the high voltages used to test dielectric withstand capability for regulatory agency electrical safety requirements.

Hold-Up Capacitor. A capacitor whose energy is used to provide output voltage for a period after the removal of input voltage.

Hold-Up Time. The length of time a power supply can operate in regulation after failure of the AC input. Linears have very short hold-up times due to the energy stored on the low-voltage secondary side output capacitors. Switchers have longer times due to higher-voltage primary-side energy storage capacitors.

Hot Swap. Insertion and extraction of a power supply into a system while power is applied.

I-Grade. Industry standard where the operation temperature of a device does not drop below –40°C.

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Impedance. The ratio of voltage to current at a specified frequency.

Induced Noise. Noise generated in a circuit by varying a magnetic field produced by another circuit.

Input Line Filter. An internally or externally mounted lowpass or band-reject filter at the power supply input that reduces the noise fed into the power supply.

Inrush Current. The peak current flowing into a power supply the instant AC power is applied. This peak may be much higher than the steady state input current due to the charging of the input filter capacitors.

Inrush Current Limiting. A circuit that limits the amount of inrush current when a power supply is turned on.

Isolation. Two circuits that are completely electrically separated with respect to DC potentials, and almost always AC potentials. In power supplies, it is defined as the electrical separation of the input and output via the transformer.

Isolation Voltage. The maximum AC or DC test voltage that may be applied from input to output and / or chassis of a power supply. Usually this has a time limit per preregulatory agency such as EN60950.

Line Voltage (Mains). The sine wave voltage provided to the power supply, usually expressed in volts rms.

Load Regulation. The change in output voltage when the load on the output is changed.

Local Sensing. Using the voltage output terminals of the power supply as sense points for voltage regulation.

Long Term Stability. Power supply output voltage change due to time with all other factors held constant. This is expressed in percent and is a function of component aging.

Low Line. The minimum steady state voltage that can be applied between the +IN and –IN pins of a converter and still maintain output regulation.

Mains. The utility AC power distribution wires.

Margining. Adjusting a power supply output voltage

up or down from its nominal setting in order to verify system performance margin with respect to supply voltage. This is usually done electrically by a systemgenerated control signal.

Intermediate Bus Architecture (IBA). A power distribution architecture that relies on non-isolated point-of-load regulators (niPOLs), reducing the POL function to regulation and transformation. The niPOLs operate from an intermediate bus voltage provided by upstream isolated converters. However, IBA has inherent limitations that require tradeoffs between distribution and conversion loss that limit responsiveness to rapid load changes. IBA has proven effective as an interim method of containing power system cost while addressing the trend toward a proliferation of lower load voltages.

Leakage Current. A term relating to current flowing between the AC supply wires and earth ground. The term does not necessarily denote a fault condition. In power supplies, leakage current usually refers to the 60 Hz current that flows through the EMC filter capacitors connected between the AC lines and ground (Y caps).

Linear Regulator. A regulating technique where a dissipative active device such as a transistor is placed in series with a power supply output to regulate the output voltage.

Line Regulation. The change in output voltage when the AC input voltage is changed from minimum to maximum specified.

MegaMod. A chassis mount packaging option that incorporates one, two or three VI- /MI-200 Family converters for single, dual or triple outputs having a combined power of up to 600 W.

M-Grade. An industry standard where the operating temperature of a device does not drop below –55°C.

MIL-SPECS. Military standards that a device must meet to be used in military environments.

MiniMod. A junior size (VI- / MI-J00) version of the VI-/MI-200 Family of DC-DC converters offering up to half the power in a 2.28" x 2.4" x 0.5" (57,9 x 61,0 x 12,7 mm) package.

Minimum Load. The minimum load current / power that must be drawn from the power supply in order for the supply to meet its performance specifications. Less frequently, a minimum load is required to prevent the power supply from failing.

Module Evaluation Board. A test fixture used to evaluate Vicor DC-DC converters.

MTBF (Mean Time Between Failure). MTBF is the point at which 63% of a given population no longer meet specification. It can either be calculated or demonstrated. The usual calculation is per MIL-STD-217 Rev. E. Demonstrated reliability is usually determined by temperature accelerated life testing and is usually greater than calculated MTBF.

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Nominal Input. The center value for the input voltage range.

Nominal Value. A usual, average, normal, or expected

perating condition. This stated value will probably not be

o equal to the value actually measured.

Offline. A power supply that receives its input power from the AC line, without using a 50 / 60 Hz power transformer prior to rectification and filtering, hence the term “offline” power supply.

Open Frame. A power supply where there is no external metal chassis; the power supply is provided to the end user essentially as a printed circuit board that provides mechanical support as well as supporting the components and making electrical connections.

Operating Temperature. The range of temperatures in which a unit can operate within specifications.

Optoisolator. An electro-optical device that transmits a signal across a DC isolation boundary.

ORing Diodes. Diodes used to isolate supplies from one another under a fault condition.

Output Filtering. Filter used to reduce switching power supply noise and ripple.

Output Good. A power supply status signal that indicates the output voltage is within a certain tolerance. An output that is either too high or too low will deactivate the Output Good signal.

Output Impedance. The ratio of change in output voltage to change in load current.

Output Noise. The AC component that may be present on the DC output of a power supply. Switch-mode power supply output noise usually has two components: a lower frequency component at the switching frequency of the converter and a high frequency component due to fast edges of the converter switching transitions. Noise should always be measured directly at the output terminals with a scope probe having an extremely short grounding lead.

Output Power Rating. The maximum power in watts that the power supply can provide and still maintain safety agency approvals.

Output Voltage Accuracy. See Setpoint Accuracy.

Overload Protection. A power supply protection circuit

that limits the output current under overload conditions.

Overshoot. A transient output voltage change exceeding the high limit of the voltage accuracy specification caused by turning the power supply on or off, or abruptly changing line or load conditions.

Overtemp Warning. A TTL compatible signal that indicates an overtemperature condition exists in the power supply.

Overvoltage Protection (OVP). A circuit that either shuts down the power supply or crowbars the output in the event of an output overvoltage condition.

Parallel Boost. VI-/MI-200 Family Booster modules may be added to a Driver to create multi-kilowatt arrays. Boosters do not contain any feedback or control circuitry.

Parallel Operation. Connecting the outputs of two or more power supplies together for the purpose of obtaining a higher output current. This requires power supplies specially designed for load sharing.

PARD. Periodic And Random Deviation. Referring to the sum of all ripple and noise components on the DC output of a power supply, regardless of nature or source.

Peak Power. The absolute maximum output power that a power supply can produce without immediate damage. Peak power capability is typically well beyond the continuous output power capability and the resulting average power should not exceed rated specifications.

Pi Filter. A commonly used filter at the input of a switching supply or DC-DC converter to reduce reflected ripple current. The filter usually consists of two shunt capacitors with inductance between them.

Post Regulator. A secondary regulating circuit on an auxiliary output of a power supply that provides regulation on that output.

Power Fail. A power supply interface signal that gives a warning that the input voltage will no longer sustain full power regulated output.

Power Factor. The ratio of true power to apparent power in an AC circuit. In power conversion technology, power factor is used in conjunction with describing AC input current to the power supply.

Preload. A small amount of current drawn from a power supply to stabilize its operation.

Primary. The input section of an isolated power supply, it is connected to the AC mains and hence has dangerous voltage levels present.

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Product Grade. The environmental and acceptance tests performed on Vicor products.

Pulse Width Modulation (PWM). A switching power conversion technique where the on-time (or width) of a duty cycle is modulated to control power transfer for regulating power supply outputs.

Push-Pull Converter. A switch-mode power supply topology that utilizes a center-tapped transformer and two power switches. The two switches are alternately driven on and off.

Quasi-Regulated Output. The regulation of an auxiliary output that is accomplished by regulation of the main output. A transformer turns ratio, commensurate with the desired auxiliary output voltage, is used in conjunction with the output around which the main control loop is closed. Quasi-regulated outputs are significantly affected by second order effects in the converter.

Remote Sense. Wires connected in parallel with power supply output cables such that the power supply can sense the actual voltage at the load to compensate for

oltage drops in the output cables and / or isolation devices.

Return. The designation of the common terminal for the power supply outputs. It carries the return current for the outputs.

Reverse Voltage Protection. A protection circuit that prevents the power supply from being damaged in the event that a reverse voltage is applied at the input or output terminals.

RFI. Radio Frequency Interference. Undesirable noise produced by a power supply or other electrical or electronic device during its operation. In power supply technology, RFI is usually taken to mean the same thing as EMC.

Ripple and Noise. The amplitude of the AC component on the DC output of a power supply usually expressed in millivolts peak-to-peak or rms. For a linear power supply it is usually at the frequency of the AC mains. For a switching power supply, it is usually at the switching frequency of the converter stage.

Rated Output Current. The maximum load current that a power supply can provide at a specified ambient temperature.

Reflected Ripple Current. The rms or peak-to-peak AC current present at the input of the power supply that is a result of the switching frequency of the converter.

Regulation. The ability of a power supply to maintain an output voltage within a specified tolerance as referenced to changing conditions of input voltage and / or load.

Regulation Band. The total error band allowable for an output voltage. This includes the effects of all of the types of regulation: line, load, temperature and time.

Regulatory Agencies. CSA: Canadian Standards Association; FCC: Federal Communications Commission; FTZ: Fernmelde Technisches Zentralamt; TÜV: Technischer Überwachungs Verein; U.L.: Underwriters Laboratory; VDE: Verband Deutscher Electrotechniker.

Remote Inhibit. A power supply interface signal, usually TTL compatible, that commands the power supply to shut down one or all outputs.

Remote On/Off. Enables power supply to be remotely turned on or off. Turn-on is typically performed by open circuit or TTL logic “1”, and turn-off by switch closure or TTL logic “0”.

Safety Ground. A conductive path to earth that is designed to protect persons from electrical shock by shunting away any dangerous currents that might occur due to malfunction or accident.

Secondary. The output section of an isolated power supply, it is isolated from the AC mains and specially designed for safety of personnel who might be working with power on the system.

SELV. An acronym for Safety Extra Low Voltage, a term generally defined by the regulatory agencies as the highest voltage that can be contacted by a person and not cause injury. It is often specifically defined as 30 Vac or 42.4 Vdc.

Setpoint Accuracy. Ratio of actual to specified output voltage.

Sequencing. The technique of establishing a desired order of activating the outputs of a multiple output power supply.

Soft Start. A technique for gradually activating a power supply circuit when the power supply is first turned on. This technique is generally used to provide a gradual rise in output voltages and inrush current limiting.

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Soft Line. A condition where there is substantial impedance present in the AC mains feeding input power to a power supply. The input voltage to the power supply drops sig-

ificantly with increasing load.

Split Bobbin Winding. A transformer winding technique where the primary and secondary are wound side-by-side on a bobbin with an insulation barrier between them.

Standby Current. The input current drawn by a power supply when shut down by a control input (remote inhibit) or under no load.

Stiff Line. A condition where there is no significant impedance present in the AC mains feeding input power to a power supply. The input voltage to the power supply does not change appreciably with load.

Switching Frequency. The rate at which the DC voltage is switched on and off in a switching power supply.

Temperature Coefficient. The average output voltage change expressed as a percent per degree Celsius of ambient temperature change. This is usually specified for a predetermined temperature range.

Undershoot. A transient output voltage change which does not meet the low limit of the voltage accuracy specification and is caused by turning the power supply on or off, or abruptly changing line or load conditions.

Universal Input. An AC input capable of operating from major AC lines worldwide, without straps or switches.

VI Chip

(VIC). VI Chips are the smallest power compo-

nents available today — about the size of a 1/16 brick and very power dense. They can be used as building blocks to replace existing circuits (quarter bricks and silver box power supplies). VI Chips offer flexible thermal management: a low thermal impedance package and the design of the package simplifies heat sink design.

Voltage Balance. The difference in magnitudes, in percent, of two output voltages that have equal nominal voltage magnitudes but opposite polarities.

Voltage Mode. A method of closed loop control of a switching converter to correct for changes in the output voltage.

Temperature Derating. Reducing the output power of a power supply with increasing temperature to maintain reliable operation.

Thermal Pad. A phase change material (ThermMate) used as a thermal interface between the converter and a heat sink or chassis.

Thermal Protection. A power supply protection circuit that shuts the power supply down in the event of unacceptably high internal temperatures.

Topology. The design type of a converter, indicative of the configuration of switching transistors, utilization of the transformer, and type of filtering. Examples of topologies are the Flyback, Forward, Half Bridge, Full Bridge, Resonant and Zero-Current-Switching.

Tracking. A characteristic in a multiple output power supply where any changes in the output voltage of one output caused by line, load, and / or temperature are proportional to similar changes in accompanying outputs.

Transient Recovery Time. The time required for an output voltage to be within specified accuracy limits after a step change in line or load conditions.

Warm-Up Drift. The initial change in the output voltage of a power supply in the time period between turn-on and when the power supply reaches thermal equilibrium at 25°C, full load and nominal line.

Warm-Up Time. The time required after initial turn-on for a power supply to achieve compliance to its performance specifications.

X-Capacitor. A capacitor connected across the supply lines to suppress normal mode interference.

True Power. In an AC circuit, true power is the actual power consumed. It is distinguished from apparent power by eliminating the reactive power component that may be present.

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Y-Capacitor. Power conversion modules generally require bypass capacitors from line to chassis (earth ground) to

hunt common-mode noise currents and keep them local

s to the converter. In cases where the converters are

perating from rectified AC line voltage, the failure of a

o bypass capacitor could result in excessive leakage current to the equipment chassis thus creating a ground fault and shock hazard. For this reason, a special classification of capacitor, referred to as a Y-capacitor, is recommended. These capacitors contain a dielectric with unique “selfhealing” properties to help prevent against excessive leakage.

To meet general EMC requirements (Section 9), Vicor recommends the use of Y-capacitors with all power conversion modules. Y-capacitors meet IEC384-14, EN132400, and UL1283 standards.

17. Glossary of Technical Terms

Zero-Current-Switching. The turn-on and turn-off of a switching device at zero current, resulting in essentially lossless switching. The zero-current-switching topology allows Vicor converters to operate at frequencies up to 1 MHz, with efficiencies higher than 80% and power densities greater than conventional topologies.

Zero-Voltage-Switching. This technique significantly minimizes the switching losses and dv/dt noise due to the discharge of the switching MOSFET junction capacitance and reverse recovery of the diode, and enables switch mode converters to operate at higher frequencies.

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Vicor’s comprehensive line of power solutions includes high density AC-DC and DC-DC modules and accessory components, fully configurable AC-DC and DC-DC power supplies, and complete custom power systems.

Information furnished by Vicor is believed to be accurate and reliable. However, no responsibility is assumed by Vicor for its use. Vicor components are not designed to be used in applications, such as life support systems, wherein a

ailure or malfunction could result in injury or death. All sales are subject to Vicor’s Terms and Conditions of Sale,

f which are available upon request.

Specifications are subject to change without notice.

Intellectual Property Notice

Vicor and its subsidiaries own Intellectual Property (including issued U.S. and Foreign Patents and pending patent applications) relating to the products described in this data sheet. Interested parties should contact Vicor's Intellectual Property Department.

Vicor Corporation

25 Frontage Road

Andover, MA, USA 01810

Tel: 800-735-6200

Fax: 978-475-6715

Customer Service:

Technical Support: apps@vicorpower.com

custserv@vicorpower.com

vicorpower.com

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