PRELIMINARY 45 Features Data Sheet MicroRAM TM Output Ripple Attenuation Module • >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 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 2 1 Product Grade C = –20°C to +100°C T = –40°C to +100°C H = –40°C to +100°C M = –55°C to +100°C Pin Style* 1 = Short Pin 2 = Long Pin S = Short ModuMate N = Long ModuMate 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 Set your site on VICOR at www.vicorpower.com Rev. 1.1 Page 1 of 8 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 Operating current range µRAM2xxx µRAM3xxx Operating input voltage Max Unit 0.02 0.02 20 30 A A 3.0 30 Vdc Transient output response Load current step <1A/µsec 50 mVp-p Step load change; see Figures 9, 12, & 15, pp. 6-7 Transient output response Load current step <1A/µsec (CTRAN = 820µF) 50 mVp-p 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. 6-7 425 mV Output ripple Input Vp-p = 100mV 10 5 mVp-p mVrms Ripple frequency 60Hz to 100kHz; optional capacitor 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 Input Vp-p = 500mV 10 5 mVp-p mVrms Ripple frequency 100kHz to 2MHz; see Figures 8, 11, & 14, pp. 6-7 VHR headroom voltage range(1) @ 1A load SC output voltage(2) Typ 325 1.23 OR’ing threshold 10 µRAM bias current 60 Notes No internal current limiting. Converter input must be properly fused such that the µRAM output current does not exceed the maximum operating current rating by more than 30% under a steady state condition. Continuous See Figures 5, 6 & 7 See Table 1 for headroom setting resistor values Vdc See Table 1 R SC value mV Vin – Vout 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 VHR @ 1A RHR 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 µRAM Out RSC Value (ohms) 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 Set your site on VICOR at www.vicorpower.com Rev. 1.1 Page 2 of 8 PRELIMINARY Electrical Characteristics (continued) APPLICATION SCHEMATIC DRAWINGS USING VICOR CONVERTERS AND THE µRAM RSENSE (2) 5.1 +In +Out PC +S 22µF DC-DC Converter PR SC SC µRAM RHR VREF CTRAN –S –In +Out +In CTRAN* CHR* –In –Out +In +Out –Out *Optional Component Figure 1—Typical Configuration using Remote Sensing +Out +In PC PR –In DC-DC Converter RSC SC SC µRAM RHR VREF CTRAN CTRAN* –Out –In CHR* –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. 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 Set your site on VICOR at www.vicorpower.com Rev. 1.1 Page 3 of 8 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 Passive Block Active Block SC VREF SC Control CTRAN +Out –Out –In µRAM 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. 1) Using ceramic load capacitance with <1milliohm ESR and <1nH ESL: (a) 20µF to 200µF requires 20nH of trace/wire load path inductance (b) 200µF to 1,000µF requires 60nH of trace/wire load path inductance Vicor Corp. Tel: 800-735-6200, 978-470-2900 Fax: 978-475-6715 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) 20µF to 200µF load capacitance needs an ESL of >50nH (b) 200µF to 1,000µF 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. MicroRAM Data Sheet Set your site on VICOR at www.vicorpower.com Rev. 1.1 Page 4 of 8 PRELIMINARY µRAM2xxx Ripple Attenuation @ 28V (Room Temp.) Ripple Attenuation @ 5V (Room Temp.) 20.00 0.00 0.00 -20.00 -20.00 Gain (dB) Gain (dB) 20.00 -40.00 -40.00 -60.00 -60.00 -80.00 -80.00 10 100 1,000 10,000 100,000 1,000,000 10,000,000 10 100 1,000 10,000 Freq. (Hz) 10A, 100uF Vref 100,000 1,000,000 10,000,000 Freq. (Hz) 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 100µF capacitor, CHR, to the VREF pin as shown in Figures 1 and 2. -0 Rhr=28k (Vheadroom=90mV) 27k (100mV) 26k (110mV) 25k (122mV) 24k (135mV) 23k (150mV) 22k (160mV) Vout=3V Iload=20A 100 degrees baseplate temperature -25 -0 Rhr=260k (Vheadroom=90mV) 250k (100mV) 240k (110mV) 230k (122mV) 220k (135mV) 210k (150mV) 200k (160mV) Vout=28V Iload=20A 100 degrees baseplate temperature -25 -50 -50 17k (260mV) 18k (240mV) 19k (217mV) 20k (197mV) 21k (180mV) -75 10Hz 100Hz 1.0KHz ... DB(V(VOUT)) 10KHz 150k (260mV) 160k (240mV) 170k (217mV) 180k (197mV) 190k (180mV) -75 100KHz 1.0MHz 10Hz 100Hz 1.0KHz ... DB(V(VOUT)) 10KHz 100KHz 1.0MHz Frequency Frequency Figure 4a-4b—Simulated graphs demonstrating the tradeoff of attenuation versus headroom setting at 20 Amps and an equivalent 100°C baseplate temperature at 3V and 28V. 28V 20A -10 -10 Rhr=260k -20 -20 100khz 3V Rhr=28k 250k 500khz 3V 27k 1Mhz 3V -30 100khz 28V 500khz 28V 1Mhz 28V 240k -30 230k 25k -40 dB dB 26k 24k 220k -40 210k 200k 23k 22k -50 190k -50 21k 180k 170k 20k 19k -60 -70 3.0 160k 18k 17k 150k -60 -70 3.5 4.0 4.5 5.0 5.5 6.0 3.0 3.5 4.0 4.5 5.0 5.5 6.0 Watts Watts 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 µRAM2C21 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 Set your site on VICOR at www.vicorpower.com Rev. 1.1 Page 5 of 8 PRELIMINARY µRAM2xxx (µRAM3xxx data not included in this rev.) 450mV 450mV VOUT=3V VOUT=15V 400mV 400mV 17k Vheadroom Vheadroom Rhr=16k 300mV Rhr=80k 300mV 85k 18k 1A 95k 20k 100k 21k 200mV 2A 4A 6A 8A V(VSOURCE) –V(VOut) 10A 12A 14A 16A 18A 90k 19k 20A 105k 200mV 1A 2A 4A 6A 8A V(VSOURCE) –V(VOut) I_Iload 10A 12A 14A 16A 18A 20A I_Iload Figure 6—Headroom vs. load current at 15V output. Figure 5—Headroom vs. load current at 3V output. 450mV VOUT=28V 400mV Vheadroom Rhr=150k 300mV 160k 170k 180k 190k 200k 200mV 1A 2A 4A 6A V(VSOURCE) –V(VOut) 8A 10A 12A 14A 16A 18A 20A I_Iload Figure 7—Headroom vs. load current at 28V output. Figure 8—V375A28C600A and µRAM; Input and output ripple @50% (10A) load CH1=Vi; CH2=Vo; Vi-Vo=332mV; RHR=178k Figure 9—V375A28C600A and µRAM; Input and output dynamic response no added CTRAN; 20% of 20A rating load step of 4A (10A➟14A);RHR=178k (Configured as in Figs. 1 & 2) Figure 10—V375A28C600A and µRAM; Input and output dynamic response CTRAN=820µF Electrolytic; 32.5% of load step of 6.5A (10A➟16.5A);RHR=178k (Configured as in Figs. 1 & 2) Vicor Corp. Tel: 800-735-6200, 978-470-2900 Fax: 978-475-6715 MicroRAM Data Sheet Set your site on VICOR at www.vicorpower.com Rev. 1.1 Page 6 of 8 PRELIMINARY µRAM2xxx Figure 11—V375B12C250A and µRAM; 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 µRAM; Input and output dynamic response no added CTRAN; 17.5% of 20A rating load step of 3.5A (10A➟13.5A);RHR=80k (Configured as in Figs. 1 & 2) Figure 13—V300B12C250A and µRAM; Input and output dynamic response CTRAN=820µF Electrolytic; 30% of load step of 6A (10A➟16A);RHR=80k (Configured as in Figs. 1 & 2) Figure 14—V48C5C100A and µRAM; 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 µRAM; Input and output dynamic response no added CTRAN; 22.5% of 20A rating load step of 4.5A (10A➟14.5A);RHR=31k (Configured as in Figs. 1 & 2) Figure 16—V48C5C100A and µRAM; Input and output dynamic response CTRAN=820µF Electrolytic; 35% of load step of 7A (10A➟17A);RHR=31k (Configured as in Figs. 1 & 2) Vicor Corp. Tel: 800-735-6200, 978-470-2900 Fax: 978-475-6715 MicroRAM Set your site on VICOR at www.vicorpower.com Rev. 1.1 Page 7 of 8 PRELIMINARY Mechanical Drawings MODULE OUTLINE 0.50 ±0.02 12,7 ±0,5 uRAM Pins Function Label +In + Control SC C ext. CTRAN –In – –Out – No. 1 2 3 4 5 style 2 & 3 baseplates only (4X)*** .275 6,99 2 12,45 ±0,38 4 uRAM 0.350±.015 8,89±0,38 (REF) 3 0.49 12,4 0.12* 0.20** 3,1 5,08 0.490 ±.015 1 Vref + 7 (REF) 0.27 (2X) 6,9 ALUMINUM BASEPLATE 2.000 50,80 6 0.21 5,2 (REF) or Threaded (Style 2) 2.28 57,9 0.65 16,5 FULL R (6X) 1.30 33,0 0.13 (6X) 3,3 5 0.080 DIA. (7X) 2,03 Slotted (Style 1) 0.09 2,3 0.10 X 45˚ 2,5 CHAMFER 1.27 32,3 OUT (ALL MARKINGS THIS SURFACE) Reference +Out 0.235±.015 5,97±0,38 (REF) 0.01 IN 6 7 0.800 20,32 0.525 13,34 0.43 10,9 0.400 10,16 1.04 26,4 1.45 36,8 0.54 (7X) 13,7 R 0.06 (3X) 1,5 Use a 4-40 Screw (6x) Torque to: 5 in-lbs 0.57 N-m 1.45 36,8 (REF.) Pin Style 1&S (Short Pin) 0.62 (7X) Pin Style 2&N 15,7 (Long Pin) 4-40 UNC-2B (6X) or Thru Hole (Style 3) * Style 1 baseplate only ** Style 2 & 3 baseplates *** Reserved for Vicor accessories Not for mounting #30 Drill Thru (6X) (0.1285) PCB MOUNTING SPECIFICATIONS 0.062 ±0.010 1,57 ±0,25 PCB THICKNESS 0.800* INBOARD SOLDER MOUNT 20,32 0.525* 13,34 PLATED THRU HOLE DIA 0.275* 6,99 0.170* 4,32 PIN STYLE 1&S (7X) 0.094 ±0.003 2,39 ±0,08 ONBOARD SOLDER MOUNT ALL MARKINGS THIS SURFACE PIN STYLE 2&N 0.094 ±0.003 2,39 ±0,08 0.133 3,38 1 2 3 4 ALUMINUM BASEPLATE 1.734** 44,04 2.000* 50,80 7 6 PINS STYLES STYLE 1 & 2: TIN/LEAD HOT SOLDER DIPPED STYLE S & N: GOLD PLATED COPPER 5 0.06 R (4X) 1,5 .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 Tol. ±0,25 0.XXX Angles ±0.01 ±1° ±0.005 ±0,127 Vicor Corp. Tel: 800-735-6200, 978-470-2900 Fax: 978-475-6715 MicroRAM Data Sheet P/N 25774 Set your site on VICOR at www.vicorpower.com Rev.1.1 11/02/10M