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
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Shown actual size: |
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2.28 x 1.45 x 0.5 in |
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57,9 x 36,8 x 12,7 mm |
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Absolute Maximum Ratings |
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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 |
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Storage temperature (H-Grade) |
-55 to +125 |
°C |
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Storage temperature (M-Grade) |
-65 to +125 |
°C |
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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 |
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Thermal Resistance |
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Parameter |
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Typ |
Unit |
Baseplate to sink; flat, greased surface |
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0.16 |
°C/Watt |
Baseplate to sink; with thermal pad (P/N 20264) |
0.14 |
°C/Watt |
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Baseplate to ambient |
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8.0 |
°C/Watt |
Baseplate to ambient; 1000 LFM |
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1.9 |
°C/Watt |
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Part Numbering
uRAM |
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2 |
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C |
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2 |
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1 |
Product |
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Type |
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Product Grade |
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2 |
= |
20A |
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C = –20°C to +100°C |
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3 |
= |
30A |
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T = –40°C to +100°C |
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H = –40°C to +100°C |
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M = –55°C to +100°C |
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Pin Style* |
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Baseplate |
1 |
= Short Pin |
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1 |
= Slotted |
2 |
= Long Pin |
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2 |
= Threaded |
S = Short ModuMate |
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3 |
= Thru-hole |
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N = Long ModuMate |
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*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 |
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No internal current limiting. Converter input must be |
µRAM2xxx |
0.02 |
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20 |
A |
properly fused such that the µRAM output current |
µRAM3xxx |
0.02 |
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30 |
A |
does not exceed the maximum operating current |
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rating by more than 30% under a steady state condition. |
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Operating input voltage |
3.0 |
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30 |
Vdc |
Continuous |
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Transient output response |
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50 |
mVp-p |
Step load change; |
Load current step <1A/µsec |
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see Figures 9, 12, & 15, pp. 6-7 |
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Transient output response |
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Optional capacitance CTRAN can be used |
Load current step <1A/µsec |
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50 |
mVp-p |
to increase transient current capability; See Figures |
(CTRAN = 820µF) |
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1 & 2 on p. 3 and Figures 10, 13, & 16 on pp. 6-7 |
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VHR headroom voltage range(1) |
325 |
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425 |
mV |
See Figures 5, 6 & 7 |
@ 1A load |
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See Table 1 for headroom setting resistor values |
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Output ripple |
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10 |
mVp-p |
Ripple frequency 60Hz to 100kHz; optional capacitor |
Input Vp-p = 100mV |
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5 |
mVrms |
CHR = 100µF required to increase low frequency |
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attenuation as shown in Figures 3a and 3b |
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see Figures 8, 11, & 14, pp. 6-7 |
Output ripple |
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10 |
mVp-p |
Ripple frequency 100kHz to 2MHz; |
Input Vp-p = 500mV |
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5 |
mVrms |
see Figures 8, 11, & 14, pp. 6-7 |
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SC output voltage(2) |
1.23 |
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Vdc |
See Table 1 RSC value |
OR’ing threshold |
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10 |
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mV |
Vin – Vout |
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µRAM bias current |
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60 |
mA |
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Power Dissipation |
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µRAM2xxx VHR = 380mV@1A |
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7.5 |
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W |
Vin = 28V; Iout = 20A |
µRAM3xxx VHR = 380mV@1A |
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11.5 |
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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 |
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5.0V |
375mV |
30.6k |
2.07k |
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12.0V |
375mV |
73.6k |
7.76k |
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15.0V |
375mV |
92.0k |
10.20k |
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24.0V |
375mV |
147.2k |
17.50k |
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28.0V |
375mV |
171.7k |
20.76k |
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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
PRELIMINARY
Electrical Characteristics (continued)
APPLICATION SCHEMATIC DRAWINGS USING VICOR CONVERTERS AND THE µRAM
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RSENSE |
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(2) |
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5.1 |
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+In |
+Out |
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+S |
22 F |
+In |
+Out |
PC |
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RHR |
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DC-DC |
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SC |
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RAM |
VREF |
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SC |
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Converter |
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CTRAN |
CHR* |
PR |
–S |
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CTRAN* |
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–In |
–Out |
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–In |
–Out |
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*Optional Component |
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Figure 1—Typical Configuration using Remote Sensing
+In |
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+Out |
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+In |
+Out |
PC |
DC-DC |
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RSC |
SC |
RHR |
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Converter |
SC |
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RAM |
VREF |
PR |
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CTRAN |
CHR* |
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–In |
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–Out |
CTRAN* |
–In |
–Out |
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*Optional Component |
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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