vicor corp. tel: 800-735-6200, 978-470-2900 fax: 978-475-6715 microram data sheet rev. 1.4 page 1 of 10 set your site on vicor at www.vicorpower.com features ? rohs compliant (with f or g pin option) ? > 40 db ripple attenuation from 60 hz to 1 mhz ? 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 ? 30 vdc 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 40 db of noise attenuation from 60 hz to 1 mhz. the microram operates over a range of 3 to 30 vdc, is available in either 20 or 30 a models and is compatible with most manufacturers switching converters including all vicor dc-dc converter models. 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. data sheet microram tm output ripple attenuation module actual size: 2.28 x 1.45 x 0.5 in 57,9 x 36,8 x 12,7 mm thermal resistance parameter typ unit baseplate to sink flat, greased surface 0.16 c/watt with thermal pad (p/n 20265) 0.14 c/watt baseplate to ambient free convection 8.0 c/watt 1000 lfm 1.9 c/watt uram 2 c 2 1 product baseplate 1 = slotted 2 = threaded 3 = thru-hole pin style* 1 = short pin 2 = long pin s = short modumate n = long modumate f = short rohs g = long rohs product grade temperatures (c) grade operating storage c = ? 20 to +100 ? 40 to +125 t = ? 40 to +100 ? 40 to +125 h = ? 40 to +100 ? 55 to +125 m = ? 55 to +100 ? 65 to +125 type 2 = 20 a 3 = 30 a part numbering *pin styles s & n are compatible with the modumate interconnect system for socketing and surface mounting. parameter rating unit notes +in to ? in 30 vdc continuous 40 vdc 100ms load current 40 adc continuous ripple input (vp-p) 100 mv 60 hzc 100 khz 500 mv 100 khz ? 2 mhz mounting torque 4 ? 6 in. lbs 6 each, 4-40 screw (0.45 ? 0.68) (nm) pin soldering temperature 500 (260) f (c) < 5 sec; wave solder 750 (390) f (c) < 7 sec; wave solder absolute maximum ratings
vicor corp. tel: 800-735-6200, 978-470-2900 fax: 978-475-6715 microram data sheet rev. 1.4 page 2 of 10 set your site on vicor at www.vicorpower.com parameter min typ max unit notes operating current range no internal current limiting. converter input must be ram2xxx 0.02 20 a properly fused such that the ram output current ram3xxx 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/sec see figures 9, 12, & 15, pp. 6-7 transient output response optional capacitance ctran can be used load current step <1a/sec 50 mvp-p to increase transient current capability; see figures (ctran = 820 f) 1 & 2 on p. 3 and figures 10, 13, & 16 on pp. 6-7 vhr headroom voltage range 1 see figures 5, 6 & 7 @ 1a load 325 425 mv see table 1 for headroom setting resistor values output ripple 10 mvp-p ripple frequency 60 hz to 100 khz; optional capacitor input vp-p = 100 mv 5 mvrms c hr = 100 f 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 100 khz to 2 mhz; input vp-p = 500 mv 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 ram bias current 60 ma power dissipation ram2xxx vhr = 380 mv@1 a 7.5 w vin = 28 v; iout = 20 a ram3xxx vhr = 380 mv@1 a 11.5 w vin = 28 v; iout = 30 a ram module specifications (-20c to +100c baseplate temperature) 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. 1 headroom is the voltage difference between the +input and +output pins. r hr = (ram +out/v hr ) x 2.3 k (see table 1 for example values) 2 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 r sc resistor values) r sc = ((ram +out)/1.23 v x 1k) ? 2 k ram out 3.0 v 5.0 v 12.0 v 15.0 v 24.0 v 28.0 v v hr @ 1a 375 mv 375 mv 375 mv 375 mv 375 mv 375 mv r hr value (ohms) 18.4 k 30.6 k 73.6 k 92.0 k 147.2 k 171.7 k r sc value (ohms) 0.439 k 2.07 k 7.76 k 10.20 k 17.50 k 20.76 k table 1 ? rhr and rsc are computed values for a 375 mv 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. 1.4 page 3 of 10 set your site on vicor at www.vicorpower.com application schematic drawings using vicor converters and the ram electrical characteristics (cont.) dc-dc converter +out vref ?out +in sc c tran ?in +out +s sc ?s ?out +in pc pr ?in r sense 5.1 22 f c tran * * optional component r hr c hr * load figure 1 ? typical configuration using remote sensing dc-dc converter +out s c ?out +in pc pr ?in ram +out vref ?out +in s c c tran ?in r s c r hr c tran * c hr * * option a l component 20 k 1 f irml6401 load 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 50 khz to 1 mhz range. an active filter provides attenuation from low frequency up to the 1 mhz range. the user must set the headroom voltage of the active block with the external r hr 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 in creased by the addition of optional c tran capacitance to the c tran pin. the low frequency ripple attenuation can be increased by addition of optional c hr capacitance to the v ref pin as shown in figures 3a and 3b, on p. 5. transient load current is supplied by the internal c tran 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 vo ltage 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 data sheet rev. 1.4 page 4 of 10 set your site on vicor at www.vicorpower.com functional description (cont.) 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 maxi, mini, micro 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. 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 c onsidered 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) 20 f to 200 f requires 20 nh of trace/wire load path inductance (b) 200 f to 1,000 f requires 60 nh of trace/wire load path inductance 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) 20 f to 200 f load capacitance needs an esl of > 50 nh (b) 200 f to 1,000 f load capacitance needs an esl of > 5 nh 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. +o u t vref ?o u t +in s c c tran ?in passive block active block sc control block diagram
vicor corp. tel: 800-735-6200, 978-470-2900 fax: 978-475-6715 microram data sheet rev. 1.4 page 5 of 10 set your site on vicor at www.vicorpower.com ripple attenuation @ 28 v (room temp.) - 8 0.00 -60.00 -40.00 -20.00 0.00 20.00 10 100 1,000 10,000 100,000 1,000,000 10,000,000 freq. (hz) gain (db) 10 a, 100 u f vref 10 a, no vref c a p ripple attenuation @ 5 v (room temp.) - 8 0.00 -60.00 -40.00 -20.00 0.00 20.00 10 100 1,000 10,000 100,000 1,000,000 10,000,000 freq. (hz) gain (db) 10 a, 100 u f vref 10 a, no vref c a p figure 3a, 3b ? curves demonstrating the small signal attenuation performance as measured on a network analyzer with a typical module at (a) 28 v and 10 a output and (b) 5 v and 10 a. the low frequency attenuation can be enhanced by connecting a 100 f capacitor, chr, to the vref pin as shown in figures 1 and 2. ram2xxx figure 3a
vicor corp. tel: 800-735-6200, 978-470-2900 fax: 978-475-6715 microram data sheet rev. 1.4 page 6 of 10 set your site on vicor at www.vicorpower.com 17 k 18 k 19 k 20 k 21 k 22 k 23 k 24 k 25 k 26 k 27 k rhr=28 k -70 -60 -50 -40 -30 -20 -10 3.0 3.5 4.0 4.5 5.0 5.5 6.0 watts 500 khz 3 v 1 mhz 3 v 100 khz 3 v db rhr = 260 k 250 k 240 k 230 k 220 k 210 k 200 k 190 k 180 k 170 k 160 k 150 k -70 -60 -50 -40 -30 -20 -10 3.0 3.5 4.0 4.5 5.0 5.5 6.0 watts db 100 khz 28 v 500 khz 28 v 1 mhz 28 v frequency 10 hz 100 hz 1.0 khz 10 khz 100 khz 1.0 mhz ... db(v(vout)) -75 -50 -25 -0 rhr = 260 k (vheadroom = 90 mv) 250 k (100 mv) 240 k (110 mv) 230 k (122 mv) 220 k (135 mv) 210 k (150 mv) 200 k (160 mv) 190 k (180 mv) 180 k (197 mv) 170 k (217 mv) 160 k (240 mv) 150 k (260 mv) vout = 28 v load = 20 a 100 degrees baseplate temperature figure 4a ? 4b ? simulated graphs demonstrating the tradeoff of attenuation versus headroom setting at 20 amps and an equivalent 100c baseplate temperature at 3 v and 28 v. frequency 10 hz 100 hz 1.0 khz 10 khz 100 khz 1.0 mhz ... db(v(vout)) -75 -50 -25 -0 vout = 3 v load = 20 a 100 degrees baseplate temperature rhr = 28 k (vheadroom = 90 mv) 27 k (100 mv) 22 k (160 mv) 23 k (150 mv) 24 k (135 mv) 25 k (122 mv) 26 k (110 mv) 17 k (260 mv) 18 k (240 mv) 19 k (217 mv) 20 k (197 mv) 21 k (180 mv) figure 4a ram2xxx figure 4c figure 4c ? 4d ? microram attenuation vs. power dissipation at 3 v 20 a, and 28 v 20 a.
vicor corp. tel: 800-735-6200, 978-470-2900 fax: 978-475-6715 microram data sheet rev. 1.4 page 7 of 10 set your site on vicor at www.vicorpower.com figure 9 ? v375a28c600b and ram; input and output dynamic response no added c tran ; 20% of 20 a rating load step of 4 a (10 a ? 14 a);r hr = 178 k (configured as in figs. 1 & 2) figure 10 ? v375a28c600b and ram; input and output dynamic response c tran = 820 f electrolytic; 32.5% of load step of 6.5 a (10 a ? 16.5 a);r hr = 178 k (configured as in figs. 1 & 2) figure 7 ? headroom vs. load current at 28 v output. 2 a 4 a 6 a 8 a 10 a 12 a 14 a 16 a 18 a 20 a 1 a 200 mv 300 mv 400 mv 450 mv v out =28 v 190k rhr=150k 160k 170k 180k 200k l load v headroom figure 5 ? headroom vs. load current at 3 v output. l lo a d 2a 4a 6a 8 a 10a 12a 14a 16a 1 8 a 20a 1a 200 mv 3 00 mv 400 mv 450 mv v out = 3 v 20k rhr=16k 17k 1 8 k 19k 21k v he a droom 2 a 4 a 6 a 8 a 10 a 12 a 14 a 16 a 18 a 20 a 1 a 200 mv 300 mv 400 mv 450 mv 100 k 90 k 85 k 95 k 105 k rhr = 80 k l load v headroom v out = 15 v ram2xxx ( ram3xxx data not included in this rev.) 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 b ack to 10a until the resulting output peak to peak was around 40mv. figure 8 ? v375a28c600b and ram; input and output ripple @50% (10 a) load ch1 = vi; ch2 = vo; vi-vo = 332 mv; rhr= 178 k figure 6 ? headroom vs. load current at 15 v output.
vicor corp. tel: 800-735-6200, 978-470-2900 fax: 978-475-6715 microram data sheet rev. 1.4 page 8 of 10 set your site on vicor at www.vicorpower.com figure 15 ? v48c5c100b and ram; input and output dynamic response no added c tran ; 22.5% of 20 a rating load step of 4.5 a (10 a ? 14.5 a);r hr = 31k (configured as in figs. 1 & 2) figure 16 ? v48c5c100b and ram; input and output dynamic response c tran = 820 f electrolytic; 35% of load step of 7 a (10 a ? 17 a);r hr =31 k (configured as in figs. 1 & 2) figure 13 ? v300b12c250b and ram; input and output dynamic response c tran = 820 f electrolytic; 30% of load step of 6 a (10 a ? 16 a);r hr = 80 k (configured as in figs. 1 & 2) figure 14 ? v48c5c100b and ram; input and output ripple @50% (10 a) load ch1 = vi; ch2 = vo; vi-vo = 327mv; r hr = 31k (configured as in figs. 1 & 2) figure 12 ? v300b12c250b and ram; input and output dynamic response no added c tran ; 17.5% of 20 a rating load step of 3.5 a (10 a ? 13.5 a);r hr = 80 k (configured as in figs. 1 & 2) figure 11 ? v375b12c250b and ram; input and output ripple@50% (10 a) load ch1 = vi; ch2 = vo; vi-vo = 305mv; r hr = 80k (configured as in figs. 1 & 2) ram2xxx
vicor corp. tel: 800-735-6200, 978-470-2900 fax: 978-475-6715 microram data sheet rev. 1.4 page 9 of 10 set your site on vicor at www.vicorpower.com mechanical drawings 5 6 7 4 3 2 1 (ref) 0.080 2,03 dia. (7x) 0.21 5,2 0.27 6,9 (2x) 1.04 26,4 1.45 36,8 .275 6,99 0.800 20,32 0.525 13,34 0.400 10,16 0.12* 3,1 0.20** 5,08 0.01 0.54 13,7 0.43 10,9 pin style 2&n (long pin) 0.62 15,7 pin style 1&s (short pin) (7x) (7x) slotted (style 1) or threaded (style 2) 4-40 unc-2b (6x) or thru hole (style 3) #30 drill thru (6x) (0.1285) (all markings this surface) aluminum baseplate 12,7 0,5 0.50 0.02 * style 1 baseplate only ** style 2 & 3 baseplates *** reserved for vicor accessories not for mounting style 2 & 3 baseplates only (4x)*** 0.490 .015 12,45 0,38 (ref) in out uram 2.000 50,80 0.235 .015 5,97 0,38 (ref) 0.350 .015 8,89 0,38 (ref) full r (6x) 0.10 2,5 chamfer (ref.) (6x) 0.65 16,5 0.49 12,4 1.30 33,0 2.28 57,9 1.45 36,8 0.13 3,3 0.06 1,5 r (3x) x 45? use a 4-40 screw (6x) torque to: 5 in-lbs 0.57 n-m 1.27 32,3 0.09 2,3 pin center line c l pin c l 23 6 1 7 4 5 plated thru hole dia 0,08 *denotes tol = 0.133 3,38 1.734** 44,04 .400* 10,16 1.140** 28,96 0.170* 4,32 0.800* 20,32 0.525* 13,34 0.275* 6,99 2.000* 50,80 0.06 1,5 r (4x) inboard solder mount short pin style 0.094 0.003 2,39 0,08 0.43 10,9 (7x) **pcb window pcb thickness 0.062 0.010 1,57 0,25 0.53 13,5 onboard solder mount long pin style 0.094 0.003 2,39 0,08 0.003 pins styles solder:tin/lead hot solder dipped modumate: gold plated copper rohs: gold plated copper aluminum baseplate all markings this surface unless otherwise specified, dimensions are in inches mm decimals tol. angles 0.xx 0.01 0,25 1 0.xxx 0.005 0,127 uram pins no. function label 1+in + 2 control sc 3 c ext. ctran 4?in ? 5?out ? 6 reference vref 7+out + figure 17 ? module outline figure 18 ? pcb mounting specifications
vicor corp. tel: 800-735-6200, 978-470-2900 fax: 978-475-6715 microram data sheet rev. 1.4 2/08 set your site on vicor at www.vicorpower.com vicor corporation 25 frontage road andover, ma, usa 01810 tel: 800-735-6200 fax: 978-475-6715 email customer service: custserv@vicorpower.com technical support: apps@vicorpower.com vicors comprehensive line of power solutions includes high density ac-dc and dc-dc modules and accessory components, fully configurable ac-dc and dc-dc power supplies, and complete custom power systems. information furnished by vicor is believed to be accurate and reliable. however, no responsibility is assumed by vicor for its use. vicor components are not designed to be used in applications, such as life support systems, wherein a failure or malfunction could result in injury or death. all sales are subject to vicor?s terms and conditions of sale, which are available upon request. specifications are subject to change without notice. intellectual property notice vicor and its subsidiaries own intellectual property (including issued u.s. and foreign patents and pending patent applications) relating to the products described in this data sheet. interested parties should contact vicor's intellectual property department. warranty vicor products are guaranteed for two years from date of shipment against defects in material or workmanship when in normal use and service. this warranty does not extend to products subjected to misuse, accident, or improper application or maintenance. vicor shall not be liable for collateral or consequential damage. this warranty is extended to the original purchaser only. except for the foregoing express warranty, vicor makes no warranty, express or implied, including, but not limited to, the warranty of merchantability or fitness for a particular purpose. vicor will repair or replace defective products in accordance with its own best judgement. for service under this warranty, the buyer must contact vicor to obtain a return material authorization (rma) number and shipping instructions. products returned without prior authorization will be returned to the buyer. the buyer will pay all charges incurred in returning the product to the factory. vicor will pay all reshipment charges if the product was defective within the terms of this warranty. information published by vicor has been carefully checked and is believed to be accurate; however, no responsibility is assumed for inaccuracies. vicor reserves the right to make changes to any products without further notice to improve reliabilit y, function, or design. vicor does not assume any liability arising out of the application or use of any product or circuit; neith er does it convey any license under its patent rights nor the rights of others. vicor general policy does not recommend the use of its components in life support applications wherein a failure or malfunction may directly threaten life or injury. per vicor terms and conditions of sale, the user of vicor components in life support applications assumes all risks of such use and indemnifies vicor against all damages.
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