Silicon Laboratories SiLinkPS-EVB User Manual

SiLINKPS-EVB USER’S GUIDE

High

Voltage

Battery Supply

Low

Voltage

VDD

Supply

Jumper

Selection

JP2, JP3,

JP4

JP6 VDD on/off

JP5 3.3 V/5 V Selector

VDC in

VBRNG

VBHI

VBLO

VDD

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1. Introduction

The SiLinkPS-EVB is a system power supply board that provides all the necessary supply voltages for a variety of Silicon Laboratories’ ProSLIC and silicon DAA evaluation boards. When used with an appropriate ac/ dc wall adapter, the SiLinkPS-EVB can provide up to 25 W of total output power. Table 1 lists some typical voltages and currents at the power supply outputs.

Table 1. Power Supply Specifications

Input/Output Voltage Current Power

VBRNG –96 V 100 mA 9.6 W

VBHI –52 V or

VBLO –26 V 200 mA 5.2 W

Any combination of outputs is possible as long as the simultaneous total power from all outputs does not exceed the maximum rated 25 W and can be sufficiently supported by the input power from the V

The SiLinkPS-EVB is designed with the same footprint as all ProSLIC evaluation board daughter cards

9–15 V 2.5 A 22–37 W

100 mA 5.2 W or

–78 V

7.8 W

3.3 V/5 V 1 A 3.3 W/5 W

allowing it to be used in conjunction with multiple ProSLIC daughter cards to create a modular evaluation platform.

The SiLinkPS-EVB circuit is based on two power supply controllers from Linear Technology that provide high efficiency and low bill-of-materials cost. Both circuits can be synchronized to the same switching frequency to reduce power supply switching noise. The outputs can be configured to support both internal and external ringing architectures by setting the provided jumpers to set the desired output voltages. Further modifications are possible to realize specific output voltage and current requirements provided the total output power does not exceed the rated maximum. Schematic capture and layout gerber files are available for integration into specific applications. Figure 1 illustrates a simplified block diagram of the SiLinkPS-EVB supply board.

2. Operating Instructions

The SiLinkPS-EVB board should always be connected to the ProSLIC evaluation board platform prior to turning on the power supply. Plugging any ProSLIC board into a live high-voltage supply can permanently damage the ProSLIC ICs. The user should exercise caution when touching any part of the SiLinkPS-EVB because dangerous high voltages are present and can cause injury.

Figure 1. SiLinkPS-EVB Power Supply Simplified Block Diagram

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FREQUENCY (kHz)

100

(kΩ)

300

1000

100

200 1000

900

800700600

500

400

2.1. High-Voltage Battery Supply

The schematic for this power circuit is illustrated in Figure 3 on page 4. The LTC3704 dc-dc controller IC is used to drive an external MOSFET and a multi-tap transformer to create four equal high-voltage negative outputs, VNEG (See Table 2), from the dc input supply. Only one output is regulated via close-loop feedback. The other three outputs are cross-regulated to the first output via the transformer ratio. The LTC3704’s negative feedback input eliminates inverting circuitry when creating negative outputs from a positive input. The six-winding 1:1 ratio transformer is configured in a manner that minimizes the need for multiple highvoltage output filter capacitors.

2.2. VNEG Voltage Adjustment

The transformer, T1, has four secondary windings, each producing an equal negative voltage, VNEG. These four windings are connected in series through the diode rectifying circuits to produce four negative voltage potentials with voltage levels equal to multiples from 1 to 4 of the VNEG magnitude. Any adjustment made to the VNEG has a direct effect on the voltage levels on all negative outputs.

Resistor R23 can be modified to realize custom output voltages as defined in the following equation.

VNEG = (1.23 x R23/R22) + 1.23

The SiLinkPS-EVB is shipped with R23 = 33.2 k and R22 = 1.65 k for VNEG equal to 26 V.

The VBLO is normally used for off-hook state and its voltage level can be programmed by the setting on the

JP7 jumper. The voltage on the VBHI and VBRNG outputs can be programmed by moving the jumper settings on JP2, JP3, and JP4. Table 2 provides several popular configurations and the required jumper settings.

2.3. Frequency Adjustment

The LTC3704 can be configured to run at switching frequencies from 50 kHz to 1 MHz allowing flexibility to choose the optimal efficiency/cost point for each specific application. Resistor R18 programs the switching frequency according to the characteristic curve shown in Figure 2.

Figure 2. Timing Resistor R18 Value

Table 2. Popular Application Configurations and Jumper Settings

Dual ProSLIC

Part Number

Si3211/Si3212 Si3220/Si3232

Si3225 N/A (external) — –52 V

PK-PK Ringing

Amplitude

75 V — –78 V

90 V –104 V

VBRNG VBHI VBLO JP2 JP3 JP4 JP7

4xVNEG

–26 V

3xVNEG

VNEG

—–26V

VNEG

–26 V

2xVNEG

Rev. 0.2 2

VNEG

2–3 2–3 1–2 2–3

1–2 — — 2–3

2–3 — 2–3 2–3

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2.4. Low Voltage VDD Supply

The low-voltage supply provides a switchable 3.3 V or 5 V output with a 1 A maximum load current. The schematic for this power supply circuit is illustrated in Figure 4 on page 5. The LT1375 IC integrated 1.5 A bipolar switching transistor and current-sensing circuitry eliminate external power transistors and sense resistors and provide a high-efficiency V footprint. The switching frequency is internally fixed at 500 kHz and can be synchronized to higher frequencies up to 1 MHz when a higher frequency signal (above 550 kHz) is provided on the SYNC pin. Table 3 provides the jumper settings for selecting a 3.3 V or 5 V output as well as for disconnecting the V

supply in a small

supply altogether.

Table 3. VDD Supply Jumper Settings

Function JP5 JP6 Comments

output

enable

3.3 V/5 V configuration

— 1–2 VDD connected

— 2–3 V

1–2 — 5 V selected

2–3 — 3.3 V selected

disconnected

2.5. Frequency Synchronization

The LTC3704 is wired as a clock master device to provide its switching frequency to the SYNC pin on the LT1375 IC. To synchronize the frequency between the two power circuits, R18 needs to be adjusted to set the LTC3704 switching frequency at or above 550 kHz. The LT1375 IC operates at its internal fixed 500 kHz and is only synchronized with the LTC3704 frequency when it senses the frequency on the SYNC pin going above 550 kHz. The SiLinkPS-EVB power circuits are designed to operate safely with switching frequency on the LTC3704 ranging from 200 kHz to 1 MHz.

2.6. Initialization Steps

1. Configure all jumpers according to the application requirements.

2. (Optional) Plug in the input power source and measure all outputs to verify correct settings.

3. Unplug input power source.

4. Assemble all ProSLIC daughter cards.

5. Plug in the input power source.

2.7. Cost-Optimized Design

The negative high-voltage circuit can be reduced for cost optimization. The four equal VNEG outputs in series arrangement provide some discrete voltage adjustments to the outputs but require additional rectifying diode circuits and increase cost. Figure 6 on page 8 illustrates a lost-optimized design with two negative outputs. The first secondary winding produces a negative voltage according to the VNEG equation described in the previous section to produce the VBLO voltage. The other three secondary windings are connected in series to produce a negative voltage with an amplitude of 3 x VNEG. This output is connected in series with the VBLO output to generate VBHI output with a voltage level of 4 x VNEG.

The use of the simplified secondary rectifying circuit, smaller transformer, and switching MOSFET lower the component costs and also reduce the maximum output power of the negative high-voltage circuit to 13 W.

Rev. 0.2 3

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IntVcc

-78Vdc

-104Vdc

-25Vdc

-96V

DC_Input

-52V

-78V

-52V

VBRNG

VBHI

VBLO

DC_Input_Diode

VDD

DC_Input_Diode

VBLO

VBHI

VBRNG

Gate

-52Vdc

VBHI JP3 JP4

-52V X 2-3

-78V 2-3 1-2

-96V 1-2 1-2

VBRNG JP2

-96V 1-2

n/c 2-3

Post-regulator

Turn-on at 9.9V

Turn-off at 9.1V

(Farside)

VBLO JP7

-25V 2-3

-50V 2-1

10uF, 25V

B1100B

JS3

CONN SOCKET 5x2

10uF, 25V

4.7k

JS1

CONN SOCKET 5x2

112

334

556

778

9910

10k

100k

C24

330uF 35V

10uH

113

C20

100pF

C25

4.7uF, 50V

LTC3704EMS

Run1NFB3Ith

Gnd

Sense

Gate

IntVcc

Vin

Freq4Mode/Sync

IRL540NS

C21

4.7uF, 10V

C22

.001uF

C19

4.7uF, 50V

R21

82k

B1100B

10k

1uF, 25V

R23

33.2k, 1%

R15

10k

R22

1.65k, 1%

R20

.02, 1%

C11

1uF, 25V

JP3

123

JP7

123

CMR3-02

JP4

123

C15

1uF, 25V

T1D

R17

4.7

T1C

C18

0.1uF

T1F

JS2

CONN SOCKET 2x2/SM

C14

.001uF

T1E

T1B

D12

B1100B

C17

10uF, 25V

C13

1uF, 100V

JS4

CONN SOCKET 5x2

JP1

CONN HEADER 2x2/SM

112

334

R14

82k

R19

R13

13k

C23

.001uF

C12

10uF, 25V

D11

B1100B

C10

1uF, 100V

FZT953CT

JS5

CONN SOCKET 5x2

112

334

556

778

9910

R11

10k

R25

47V

JP2

123

T1A

VP5

R18

31.6k, 1%

D10

47V

4 Rev. 0.2

Figure 3. High-Voltage Negative Battery Supply

+ 8 hidden pages

Silicon Laboratories SiLinkPS-EVB User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual