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PRELIMINARY
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
Data Sheet
MICRORAM
TM
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
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.
Absolute Maximum Ratings
Parameter +In to -In +In to -In Load current Ripple Input (Vp-p) Ripple Input (Vp-p) Mounting torque Pin soldering temperature Pin soldering temperature Storage temperature (C, T-Grade) Storage temperature (H-Grade) Storage temperature (M-Grade) Operating temperature (C-Grade) Operating temperature (T, H-Grade) Operating temperature (M-Grade) Rating 30 40 40 100 500 4-6 (0.45-0.68) 500 (260) 750 (390) -40 to +125 -55 to +125 -65 to +125 -20 to +100 -40 to +100 -55 to +100 Unit Vdc Vdc Adc mV mV In. lbs (Nm) F (C) F (C) C C C C C C Notes Continuous 100ms Continuous 60Hzc100 kHz 100kHz-2MHz 6 each, 4-40 screw 5 sec; wave solder 7 sec; wave solder
Baseplate Baseplate Baseplate
Thermal Resistance
Parameter Baseplate to sink; flat, greased surface Baseplate to sink; with thermal pad (P/N 20264) Baseplate to ambient Baseplate to ambient; 1000 LFM Typ 0.16 0.14 8.0 1.9 Unit C/Watt C/Watt C/Watt C/Watt
Part Numbering
uRAM
Product
2
Type 2 = 20A 3 = 30A
C
Product Grade C = -20C to +100C T = -40C to +100C H = -40C to +100C M = -55C to +100C
2
Pin Style* 1 = Short Pin 2 = Long Pin S = Short ModuMate N = Long ModuMate
1
Baseplate 1 = Slotted 2 = Threaded 3 = Thru-hole
*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
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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.
RAM MODULE SPECIFICATIONS (-20C to +100C baseplate temperature)
Parameter Operating current range RAM2xxx RAM3xxx Operating input voltage Transient output response Load current step <1A/sec Transient output response Load current step <1A/sec (CTRAN = 820F) VHR headroom voltage range(1) @ 1A load Output ripple Input Vp-p = 100mV 325 Min 0.02 0.02 3.0 Typ Max 20 30 30 50 Unit A A Vdc mVp-p Notes No internal current limiting. Converter input must be properly fused such that the RAM output current does not exceed the maximum operating current rating by more than 30% under a steady state condition. Continuous Step load change; see Figures 9, 12, & 15, pp. 6-7 Optional capacitance CTRAN can be used to increase transient current capability; See Figures 1 & 2 on p. 3 and Figures 10, 13, & 16 on pp. 6-7 See Figures 5, 6 & 7 See Table 1 for headroom setting resistor values Ripple frequency 60Hz to 100kHz; optional capacitor CHR = 100F required to increase low frequency attenuation as shown in Figures 3a and 3b see Figures 8, 11, & 14, pp. 6-7 Ripple frequency 100kHz to 2MHz; see Figures 8, 11, & 14, pp. 6-7 See Table 1 RSC value Vin - Vout
50
mVp-p
425 10 5
mV mVp-p mVrms
Output ripple Input Vp-p = 500mV SC output voltage(2) OR'ing threshold RAM bias current Power Dissipation RAM2xxx VHR = 380mV@1A RAM3xxx VHR = 380mV@1A 7.5 11.5 1.23 10
10 5
mVp-p mVrms Vdc mV
60
mA W W Vin = 28V; Iout = 20A Vin = 28V; Iout = 30A
(1)
Headroom is the voltage difference between the +Input and +Output pins. RHR = (RAM +Out/VHR) x 2.3k (see Table 1 for example values) SC resistor is required to trim the converter output up to accommodate the headroom of the RAM 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 = ((RAM +Out)/1.23V x 1k) - 2k
(2)
RAM Out 3.0V 5.0V 12.0V 15.0V 24.0V 28.0V
VHR @ 1A 375mV 375mV 375mV 375mV 375mV 375mV
RHR Value (ohms) 18.4k 30.6k 73.6k 92.0k 147.2k 171.7k
RSC Value (ohms) 0.439k 2.07k 7.76k 10.20k 17.50k 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
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PRELIMINARY
Electrical Characteristics (continued)
APPLICATION SCHEMATIC DRAWINGS USING VICOR CONVERTERS AND THE RAM
RSENSE
(2) 5.1 +In +Out 22F PC +S +In SC SC CTRAN -S +Out
DC-DC Converter
PR -In
RAM
RHR VREF CHR*
-Out
CTRAN*
-In
-Out
*Optional Component
Figure 1--Typical Configuration using Remote Sensing
+In PC PR -In
+Out
+In
+Out
DC-DC Converter
RSC
SC
SC CTRAN
RAM
RHR VREF CHR*
-Out
-Out
CTRAN* *Optional Component
-In
Figure 2--Typical Configuration using SC Control (Oppional CHR 25F 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.
Vicor Corp. Tel: 800-735-6200, 978-470-2900 Fax: 978-475-6715
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).
MICRORAM Rev. 1.1 Page 3 of 8
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PRELIMINARY
Functional Description (continued)
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 (see Figures 5, 6 & 7, p. 6). 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 Amps, for example, the 1 Amp headroom can be set 75mV lower to conserve power and still have active headroom at the maximum load current of 10 Amps. The high end or maximum headroom range is limited by the internal OR'ing diode function. 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 1.23 Volt reference and a 1k ohm input impedance like Vicor 2nd Generation 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 OR'ing feature prevents current flowing from the output of the MICRORAM back through it's 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 OR'ed output voltage potential of the redundant system, the input of the MICRORAM is isolated from it's output. Less than 50mA will flow out of the input terminal of the MICRORAM over the full range of input voltage under this condition.
+In SC CTRAN -In
Passive Block
Active Block
+Out
SC Control
VREF
-Out
RAM Block Diagram
Application Notes
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 inductance of the load path, the capacitor type and value as well as its ESR and ESL also affect transient capability at the load. The following guidelines should be considered when point of load capacitance is used with the MICRORAM in order to maintain a minimum of 30 degrees of phase margin. 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 milliohm: (a) 20F to 200F load capacitance needs an ESL of >50nH (b) 200F to 1,000F load capacitance needs an ESL of >5nH 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.
1) Using ceramic load capacitance with <1milliohm ESR and <1nH ESL: (a) 20F to 200F requires 20nH of trace/wire load path inductance (b) 200F to 1,000F requires 60nH of trace/wire load path inductance
Vicor Corp. Tel: 800-735-6200, 978-470-2900 Fax: 978-475-6715
MICRORAM Data Sheet
Rev. 1.1
Page 4 of 8
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PRELIMINARY
RAM2xxx
Ripple Attenuation @ 28V (Room Temp.)
20.00 20.00
Ripple Attenuation @ 5V (Room Temp.)
0.00
0.00
-20.00 Gain (dB) Gain (dB) -40.00
-20.00
-40.00
-60.00
-60.00
-80.00 10 100 1,000 10,000 Freq. (Hz) 100,000 1,000,000 10,000,000
-80.00 10 100 1,000 10,000 Freq. (Hz) 100,000 1,000,000 10,000,000
10A, 100uF Vref
10A, No Vref Cap
10A, 100uF Vref
10A, No Vref Cap
Figure 3a, 3b--Curves demonstrating the small signal attenuation performance as measured on a network analyzer with a typical module at (a) 28V and 10A output and (b) 5V and 10A. The low frequency attenuation can be enhanced by connecting a 100F capacitor, CHR, to the VREF pin as shown in Figures 1 and 2.
-0 Vout=3V Iload=20A 100 degrees baseplate temperature Rhr=28k (Vheadroom=90mV) 27k (100mV) 26k (110mV) 25k (122mV) 24k (135mV) 23k (150mV) 22k (160mV) -0 Vout=28V Iload=20A 100 degrees baseplate temperature Rhr=260k (Vheadroom=90mV) 250k (100mV) 240k (110mV) 230k (122mV) 220k (135mV) 210k (150mV) 200k (160mV)
-25
-25
-50
-50
-75
17k (260mV) 18k (240mV) 19k (217mV) 20k (197mV) 21k (180mV) 100Hz 1.0KHz ... DB(V(VOUT)) Frequency 10KHz 100KHz 1.0MHz
-75
150k (260mV) 160k (240mV) 170k (217mV) 180k (197mV) 190k (180mV) 100Hz 1.0KHz ... DB(V(VOUT)) Frequency 10KHz 100KHz 1.0MHz
10Hz
10Hz
Figure 4a-4b--Simulated graphs demonstrating the tradeoff of attenuation versus headroom setting at 20 Amps and an equivalent 100C baseplate temperature at 3V and 28V.
-10 -20
Rhr=28k 27k 100khz 3V 500khz 3V 1Mhz 3V 26k
dB
-10
Rhr=260k
28V 20A
-20 -30 -40 -50
dB
250k 240k 230k
100khz 28V 500khz 28V 1Mhz 28V
-30 -40 -50 -60 -70 3.0
25k 24k 23k 22k 21k 20k
220k 210k 200k 190k 180k 170k 160k 150k
19k
18k 17k
-60 -70
3.5
4.0
4.5
Watts
5.0
5.5
6.0
3.0
3.5
4.0
4.5
Watts
5.0
5.5
6.0
Figure 4c-4d--MICRORAM attenuation vs. power dissipation at 3V 20A, and 28V 20A.
Notes:The measurements in Figures 8-16 were taken with a RAM2C21 and standard scope probes with a 20MHz bandwidth scope setting. The criteria for transient current capability was as follows: The transient load current step was incremented from 10A to the peak value indicated, then stepped back to 10A until the resulting output peak to peak was around 40mV.
Vicor Corp. Tel: 800-735-6200, 978-470-2900 Fax: 978-475-6715
MICRORAM
Rev. 1.1
Page 5 of 8
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PRELIMINARY
RAM2xxx (RAM3xxx data not included in this rev.)
450mV
450mV
VOUT=3V 400mV 400mV
VOUT=15V
Figure 5--Headroom vs. load current at 3V output.
Figure 7--Headroom vs. load current at 28V output.
Figure 9--V375A28C600A and RAM; Input and output dynamic response no added CTRAN; 20% of 20A rating load step of 4A (10A14A);RHR=178k (Configured as in Figs. 1 & 2)
Vicor Corp. Tel: 800-735-6200, 978-470-2900 Fax: 978-475-6715
Vheadroom Vheadroom
Vheadroom
Rhr=16k 300mV 17k 18k 19k 20k 200mV 21k
Rhr=80k 300mV 85k 90k 95k 100k 200mV 105k
1A
2A
4A
6A
8A
10A I_Iload
12A
14A
16A
18A
20A
1A
2A
4A
6A
8A
10A I_Iload
12A
14A
16A
18A
20A
V(VSOURCE) -V(VOut)
V(VSOURCE) -V(VOut)
Figure 6--Headroom vs. load current at 15V output.
450mV
VOUT=28V 400mV
Rhr=150k 300mV 160k 170k 180k 190k 200mV 200k
1A
2A
4A
6A
8A
10A I_Iload
12A
14A
16A
18A
20A
V(VSOURCE) -V(VOut)
Figure 8--V375A28C600A and RAM; Input and output ripple @50% (10A) load CH1=Vi; CH2=Vo; Vi-Vo=332mV; RHR=178k
Figure 10--V375A28C600A and RAM; Input and output dynamic response CTRAN=820F Electrolytic; 32.5% of load step of 6.5A (10A16.5A);RHR=178k (Configured as in Figs. 1 & 2)
MICRORAM Data Sheet Rev. 1.1 Page 6 of 8
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PRELIMINARY
RAM2xxx
Figure 11--V375B12C250A and RAM; Input and output ripple @50% (10A) load CH1=Vi; CH2=Vo; Vi-Vo=305mV; RHR=80k (Configured as in Figs. 1 & 2)
Figure 12--V300B12C250A and RAM; Input and output dynamic response no added CTRAN; 17.5% of 20A rating load step of 3.5A (10A13.5A);RHR=80k (Configured as in Figs. 1 & 2)
Figure 13--V300B12C250A and RAM; Input and output dynamic response CTRAN=820F Electrolytic; 30% of load step of 6A (10A16A);RHR=80k (Configured as in Figs. 1 & 2)
Figure 14--V48C5C100A and RAM; Input and output ripple @50% (10A) load CH1=Vi; CH2=Vo; Vi-Vo=327mV; RHR=31k (Configured as in Figs. 1 & 2)
Figure 15--V48C5C100A and RAM; Input and output dynamic response no added CTRAN; 22.5% of 20A rating load step of 4.5A (10A14.5A);RHR=31k (Configured as in Figs. 1 & 2)
Vicor Corp. Tel: 800-735-6200, 978-470-2900 Fax: 978-475-6715
Figure 16--V48C5C100A and RAM; Input and output dynamic response CTRAN=820F Electrolytic; 35% of load step of 7A (10A17A);RHR=31k (Configured as in Figs. 1 & 2)
MICRORAM Rev. 1.1 Page 7 of 8
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PRELIMINARY
Mechanical Drawings
MODULE OUTLINE
0.50 0.02 12,7 0,5
No. 1 2 3 4 5 6 7
uRAM Pins Function Label +In + Control SC C ext. CTRAN -In - -Out - Reference +Out Vref +
0.800 20,32 0.525 13,34
0.235.015 5,970,38 (REF)
style 2 & 3 baseplates only (4X)***
0.01
.275 6,99
0.12* 0.20** 3,1 5,08
0.49 12,4
1.27 32,3
0.490 .015
1
(ALL MARKINGS THIS SURFACE)
2
3
4
12,45 0,38
(REF) 0.27 (2X) 6,9 0.65 16,5 1.30 33,0
0.09 2,3 0.10 X 45 2,5 CHAMFER
IN
0.350.015 8,890,38 (REF)
2.000 50,80
ALUMINUM BASEPLATE
2.28 57,9
FULL R (6X) 0.13 (6X) 3,3
uRAM OUT
6 5
7
0.080 DIA. (7X) 2,03 0.400 10,16 1.04 26,4 1.45 36,8
0.43 10,9 0.54 (7X) 13,7
R
0.06 (3X) 1,5
Slotted (Style 1) or Threaded (Style 2)
4-40 UNC-2B (6X)
0.21 5,2 (REF)
Pin Style 1&S
(Short Pin)
1.45 36,8 (REF.)
Use a 4-40 Screw (6x) Torque to: 5 in-lbs 0.57 N-m
0.62 (7X) Pin Style 2&N 15,7 (Long Pin)
or Thru Hole (Style 3)
#30 Drill Thru (6X) (0.1285)
* Style 1 baseplate only ** Style 2 & 3 baseplates *** Reserved for Vicor accessories Not for mounting
PCB MOUNTING SPECIFICATIONS
PCB THICKNESS
0.062 0.010 1,57 0,25
0.800* 20,32 0.525* 13,34 0.275* 6,99 0.170* 4,32 PLATED THRU HOLE DIA 0.133 3,38 1 2 3 4 ALUMINUM BASEPLATE PINS STYLES STYLE 1 & 2: TIN/LEAD HOT SOLDER DIPPED STYLE S & N: GOLD PLATED COPPER INBOARD SOLDER MOUNT PIN STYLE 1&S (7X) 0.094 0.003 2,39 0,08 ONBOARD SOLDER MOUNT PIN STYLE 2&N 0.094 0.003 2,39 0,08
ALL MARKINGS THIS SURFACE
2.000* 50,80
1.734** 44,04
7 0.06 R (4X) 1,5
6
5
.400* 10,16 1.140** 28,96
*DENOTES TOL = 0.003 0,08 **PCB WINDOW
0.43 10,9
0.53 13,5
Unless otherwise specified, dimensions are in inches mm Decimals 0.XX 0.XXX Tol. 0.01 0,25 0.005 0,127 1 Angles
Vicor Corp. Tel: 800-735-6200, 978-470-2900 Fax: 978-475-6715
MICRORAM Data Sheet
P/N 25774
Rev.1.1
11/02/10M
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