VICOR URAM3TS3, URAM3TS1, URAM3TN3, URAM3TN2, URAM3TN1, URAM3T23, URAM3T22, URAM3T21, URAM3T13, URAM3T11, URAM3MS3, URAM3MS2, URAM3MS1, URAM3MN3, URAM3H11, URAM3CS3, URAM3CS2, URAM3CS1, URAM3CN3, URAM3CN2, URAM3CN1, URAM3C23, URAM3C22, URAM3C21, URAM3C13, URAM2TS3, URAM2TS2, URAM2TS1, URAM2TN3, URAM2TN2, URAM2TN1, URAM2T23, URAM2T22, URAM3MN2, URAM3MN1, URAM3M23, URAM3M22, URAM3M21, URAM3M13, URAM3M12, URAM3M11, URAM3HS3, URAM3HS2, URAM3HS1, URAM3HN3, URAM3HN2, URAM3HN1, URAM3H23, URAM3H22, URAM3H21, URAM3H13, URAM3H12, URAM2M12, URAM2HS3, URAM2HS2, URAM2HS1, URAM2HN3, URAM2HN2, URAM2HN1, URAM2T21, URAM2T13, URAM2T11, URAM2MN2, URAM2MN1, URAM2M23, URAM2M22, URAM2M21, URAM2M13, URAM2H23, URAM2H22, URAM2H21, URAM2H13, URAM2H11, URAM2CS3, URAM2CS2, URAM2CS1, URAM2CN2, URAM2CN1, URAM2C23, URAM2C22, URAM2C21, URAM2C13, URAM2C12, URAM2C11 Datasheet

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45

Features

>40dB ripple attenuation from 60Hz to 1MHz

Integrated OR’ing diode supports N+1 redundancy

Significantly improves load transient response

Efficiency up to 98%

User selectable performance optimization

Combined active and passive filtering

3-30Vdc input range

20 and 30 Ampere ratings

Product Highlights

Vicor’s MicroRAM output ripple attenuation module combines both active and passive filtering to achieve greater than 40dB of noise attenuation from 60Hz to 1Mhz. The MicroRAM operates over a range of 3 to 30Vdc, is available in either 20 or 30A models and is compatible with most manufacturers switching converters including Vicor’s 1st and 2nd Generation DC-DC converters.

The MicroRAM’s closed loop architecture greatly improves load transient response and with dual mode control, insures precise point of load voltage regulation, The MicroRAM supports redundant and parallel operation with its integrated OR’ing diode function.

It is available in Vicor’s standard micro package (quarter brick) with a variety of terminations for through hole, socket or surface mount applications.

PRELIMINARY

Data Sheet

MicroRAMTM

Output Ripple Attenuation Module

Patents Pending

 

 

 

Shown actual size:

 

 

2.28 x 1.45 x 0.5 in

 

 

57,9 x 36,8 x 12,7 mm

Absolute Maximum Ratings

 

 

 

 

 

 

 

 

 

 

 

Parameter

Rating

Unit

Notes

+In to –In

30

Vdc

Continuous

+In to –In

40

Vdc

100ms

Load current

40

Adc

Continuous

Ripple Input (Vp-p)

100

mV

60Hzc100 kHz

Ripple Input (Vp-p)

500

mV

100kHz–2MHz

Mounting torque

4-6 (0.45-0.68)

In. lbs (Nm)

6 each, 4-40 screw

Pin soldering temperature

500 (260)

°F (°C)

5sec; wave solder

Pin soldering temperature

750 (390)

°F (°C)

7sec; wave solder

Storage temperature (C, T-Grade)

-40 to +125

°C

 

Storage temperature (H-Grade)

-55 to +125

°C

 

Storage temperature (M-Grade)

-65 to +125

°C

 

Operating temperature (C-Grade)

-20 to +100

°C

Baseplate

Operating temperature (T, H-Grade)

-40 to +100

°C

Baseplate

Operating temperature (M-Grade)

-55 to +100

°C

Baseplate

 

 

 

 

Thermal Resistance

 

 

 

 

 

 

 

 

 

 

 

Parameter

 

Typ

Unit

Baseplate to sink; flat, greased surface

 

0.16

°C/Watt

Baseplate to sink; with thermal pad (P/N 20264)

0.14

°C/Watt

Baseplate to ambient

 

8.0

°C/Watt

Baseplate to ambient; 1000 LFM

 

1.9

°C/Watt

 

 

 

 

Part Numbering

uRAM

 

2

 

C

 

2

 

1

Product

 

 

Type

 

Product Grade

 

2

=

20A

 

C = –20°C to +100°C

 

 

 

 

3

=

30A

 

T = –40°C to +100°C

 

 

 

 

 

 

H = –40°C to +100°C

 

 

 

 

 

 

M = –55°C to +100°C

 

 

 

 

 

 

 

 

Pin Style*

 

 

Baseplate

1

= Short Pin

 

1

= Slotted

2

= Long Pin

 

2

= Threaded

S = Short ModuMate

 

3

= Thru-hole

N = Long ModuMate

 

 

 

 

 

 

 

 

 

 

 

*Pin styles S & N are compatible with the ModuMate interconnect system for socketing and surface mounting.

Vicor Corp. Tel: 800-735-6200, 978-470-2900 Fax: 978-475-6715

MicroRAM

Rev. 1.1

Page 1 of 8

Set your site on VICOR at www.vicorpower.com

PRELIMINARY

Electrical Characteristics

Electrical characteristics apply over the full operating range of input voltage, output power and baseplate temperature, unless otherwise specified. All temperatures refer to the operating temperature at the center of the baseplate.

µRAM MODULE SPECIFICATIONS (-20°C to +100°C baseplate temperature)

Parameter

Min

Typ

Max

Unit

Notes

Operating current range

 

 

 

 

No internal current limiting. Converter input must be

µRAM2xxx

0.02

 

20

A

properly fused such that the µRAM output current

µRAM3xxx

0.02

 

30

A

does not exceed the maximum operating current

 

 

 

 

 

rating by more than 30% under a steady state condition.

 

 

 

 

 

 

Operating input voltage

3.0

 

30

Vdc

Continuous

 

 

 

 

 

 

Transient output response

 

 

50

mVp-p

Step load change;

Load current step <1A/µsec

 

 

see Figures 9, 12, & 15, pp. 6-7

 

 

 

 

 

 

 

 

 

 

Transient output response

 

 

 

 

Optional capacitance CTRAN can be used

Load current step <1A/µsec

 

 

50

mVp-p

to increase transient current capability; See Figures

(CTRAN = 820µF)

 

 

 

 

1 & 2 on p. 3 and Figures 10, 13, & 16 on pp. 6-7

 

 

 

 

 

 

VHR headroom voltage range(1)

325

 

425

mV

See Figures 5, 6 & 7

@ 1A load

 

See Table 1 for headroom setting resistor values

 

 

 

 

 

 

 

 

 

 

Output ripple

 

 

10

mVp-p

Ripple frequency 60Hz to 100kHz; optional capacitor

Input Vp-p = 100mV

 

 

5

mVrms

CHR = 100µF required to increase low frequency

 

 

 

 

 

attenuation as shown in Figures 3a and 3b

 

 

 

 

 

see Figures 8, 11, & 14, pp. 6-7

Output ripple

 

 

10

mVp-p

Ripple frequency 100kHz to 2MHz;

Input Vp-p = 500mV

 

 

5

mVrms

see Figures 8, 11, & 14, pp. 6-7

 

 

 

 

 

 

SC output voltage(2)

1.23

 

 

Vdc

See Table 1 RSC value

OR’ing threshold

 

10

 

mV

Vin – Vout

 

 

 

 

 

 

µRAM bias current

 

 

60

mA

 

 

 

 

 

 

 

Power Dissipation

 

 

 

 

 

µRAM2xxx VHR = 380mV@1A

 

7.5

 

W

Vin = 28V; Iout = 20A

µRAM3xxx VHR = 380mV@1A

 

11.5

 

W

Vin = 28V; Iout = 30A

(1) Headroom is the voltage difference between the +Input and +Output pins.

RHR = (µRAM +Out/VHR) x 2.3k (see Table 1 for example values)

(2)SC resistor is required to trim the converter output up to accommodate the headroom of the µRAM module when remote sense is not used. This feature can only be used when the trim reference of the converter is in the 1.21 to 1.25 Volt range.

(see Table 1 with calculated RSC resistor values)

RSC = ((µRAM +Out)/1.23V x 1k) – 2k

µRAM Out

VHR @ 1A

RHR Value (ohms)

RSC Value (ohms)

3.0V

375mV

18.4k

0.439k

 

 

 

 

5.0V

375mV

30.6k

2.07k

 

 

 

 

12.0V

375mV

73.6k

7.76k

 

 

 

 

15.0V

375mV

92.0k

10.20k

 

 

 

 

24.0V

375mV

147.2k

17.50k

 

 

 

 

28.0V

375mV

171.7k

20.76k

 

 

 

 

Table 1—RHR and RSC are computed values for a 375mV case. To compute different headroom voltages, or for standard resistor values and tolerances, use Notes 1 and 2.

Vicor Corp. Tel: 800-735-6200, 978-470-2900 Fax: 978-475-6715

MicroRAM Data Sheet

Rev. 1.1

Page 2 of 8

Set your site on VICOR at www.vicorpower.com

VICOR URAM3TS3, URAM3TS1, URAM3TN3, URAM3TN2, URAM3TN1, URAM3T23, URAM3T22, URAM3T21, URAM3T13, URAM3T11, URAM3MS3, URAM3MS2, URAM3MS1, URAM3MN3, URAM3H11, URAM3CS3, URAM3CS2, URAM3CS1, URAM3CN3, URAM3CN2, URAM3CN1, URAM3C23, URAM3C22, URAM3C21, URAM3C13, URAM2TS3, URAM2TS2, URAM2TS1, URAM2TN3, URAM2TN2, URAM2TN1, URAM2T23, URAM2T22, URAM3MN2, URAM3MN1, URAM3M23, URAM3M22, URAM3M21, URAM3M13, URAM3M12, URAM3M11, URAM3HS3, URAM3HS2, URAM3HS1, URAM3HN3, URAM3HN2, URAM3HN1, URAM3H23, URAM3H22, URAM3H21, URAM3H13, URAM3H12, URAM2M12, URAM2HS3, URAM2HS2, URAM2HS1, URAM2HN3, URAM2HN2, URAM2HN1, URAM2T21, URAM2T13, URAM2T11, URAM2MN2, URAM2MN1, URAM2M23, URAM2M22, URAM2M21, URAM2M13, URAM2H23, URAM2H22, URAM2H21, URAM2H13, URAM2H11, URAM2CS3, URAM2CS2, URAM2CS1, URAM2CN2, URAM2CN1, URAM2C23, URAM2C22, URAM2C21, URAM2C13, URAM2C12, URAM2C11 Datasheet

PRELIMINARY

Electrical Characteristics (continued)

APPLICATION SCHEMATIC DRAWINGS USING VICOR CONVERTERS AND THE µRAM

 

 

RSENSE

 

 

(2)

 

5.1

 

 

+In

+Out

 

 

 

 

 

 

+S

22 F

+In

+Out

PC

 

 

RHR

 

DC-DC

 

SC

 

 

 

 

 

RAM

VREF

 

SC

 

 

Converter

 

CTRAN

CHR*

PR

–S

 

 

CTRAN*

 

 

 

–In

–Out

 

 

–In

–Out

 

 

 

 

 

 

 

 

 

*Optional Component

 

 

Figure 1—Typical Configuration using Remote Sensing

+In

 

+Out

 

+In

+Out

PC

DC-DC

 

RSC

SC

RHR

 

Converter

SC

 

RAM

VREF

PR

 

 

CTRAN

CHR*

 

 

 

 

 

–In

 

–Out

CTRAN*

–In

–Out

 

 

 

*Optional Component

 

 

Figure 2—Typical Configuration using SC Control (Oppional CHR 25µF maximum in SC configuration.)

Functional Description

The MicroRAM has an internal passive filter that effectively attenuates ripple in the 50kHz to 1MHz range. An active filter provides attenuation from low frequency up to the 1MHz 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 1 or 2 depending on the load sensing method. The transient load current performance can be increased by the addition of optional CTRAN 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 3a and 3b, on p. 5.

Transient load current is supplied by the internal CTRAN 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 8-16, on pp. 6 and 7, for examples of dynamic performance. A larger headroom voltage setting will provide increased transient performance, ripple attenuation and power dissipation while reducing overall efficiency (see Figures 4a, 4b, 4c and 4d on p. 5).

Vicor Corp. Tel: 800-735-6200, 978-470-2900 Fax: 978-475-6715

MicroRAM

Rev. 1.1

Page 3 of 8

Set your site on VICOR at www.vicorpower.com

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