rev1.0 4/29/2005 IRDC3637eval 1 ir3637 evaluation board user guide description the ir3637 controller ic is designed to provide a low cost synchronous buck regulator for on-board dc to dc applications in a small 8-pin soic. the output voltage can be precisely regulated using the internal 0.8v reference voltage for low voltage applications. the ir3637 operates at a fixed internal 400khz switching freq uency to reduce the component size. the device features under-voltage lockout for both input supplies, an external programmable soft-start function as well as output under-voltage detection that latches off the device when an output short is detected. input / output connections the following is the input / output connections: inputs:jp1: input (+5v) and gnd ju1: v c outputs: jp2: v out (+1.8v) and gnd other connections: j1: scope connection for v out j2: scope connection for inductor point specification data v c = 12v v cc =v in =5v v out =1.8v iout =7a output ripple = 50mv f s = 400khz the reference board is designed for 1.8v output using +5v and +12v supplies. this will demonstrate the main features of ic. this user guide contains the schematic and bill of materi als, the design guidelines are described in data sheet. the connection points are shown in figure1. connect the power supply cables according to this figure, minimizing wire lengths to reduce losses in the wire. test points j1 and j2 provide easy connection for oscilloscope voltage probe to monitor the inductor points and output voltage. package information fb vcc ldrv gnd hdrv vc comp ss/sd 4 3 2 1 5 6 7 8 downloaded from: http:///
rev1.0 4/29/2005 IRDC3637eval 2 connection diagram figure 1 C connection diagram of evaluation board for ir3637 +5vsupply +12vsupply 7aload downloaded from: http:///
rev1.0 4/29/2005 IRDC3637eval layout the top side (component) layer for ir3637 eval board is shown in figure 2. the input capacit ors are all located close to the mosfets. all the decoupling capacitors, and feedback components are located close to ic. the feedback resistors are tied to the output voltage at the point of regulation. the pcb is 4-laye rs board, one layer is dedicated to power gnd and the analog gnd is kept separated from the pgnd and it is connected at a single point. figure 2 C top layer of evaluation board for ir3637 3 downloaded from: http:///
rev1.0 4/29/2005 IRDC3637eval schematic figure 3 C schematic of the evaluation board 4 1 2 34 a b c d 4 3 2 1 d c b a title number revi sion si ze orcad a date: 10-mar-2005 sheet of file: c:\pcb2\pcb_last6 .dd b drawn by: vo vin + c12 l1 + c13 + c9 + c8 in pu t ou tp ut + vi n gn d jp1 jp2 d3 d1 bat54sct ldr v ss comp fb n15 n40 hdrv vgh vgl j1 n25 vc ju1 ir3637 - dual so8 mosfet vcc je3637s-v1r0 ss 8 comp 7 vc 6 hdrv 5 fb 1 vcc 2 ldr v 3 gnd 4 u1 ir36 37 gnd vo s1 g1 s2 g2 d1 d1 d2 d2 q1 mosfet n_dual c10 c6 c5 c1 c2 c11 c3 c4 c7 r3 r1 r2 r9 r8 r10 r7 r6 r4 r5 j2 vc/vcc lx downloaded from: http:///
rev1.0 4/29/2005 IRDC3637eval bill of material ref desig description value qty part# manuf q1 dual mosfet 20v, 13.4mohm 1 irf8910 ir u1 controller synchronous pwm 1 ir3637 ir d3 diode fast switching 1 bat54a ir l1 inductor 1.5uh, 8a, 10 mohm 1 do3316p-152 coilcraft c8,9,12,13 cap, poscap 150uf, 6.3v, 40mohm 4 6tpc150m sanyo c2,c5 cap, ceramic 0.1uf, x7r, 16v 2 ecj-1vb1c104k panasonic c1,10,11 cap, ceramic 1uf, x5r, 6.3v 3 ecj-1vb0j105k panasonic c3 cap, ceramic 22pf, npo, 100v 1 ecj-1vc2a220j panasonic c4 cap, ceramic 1800pf, x7r, 50v 1 ecj-1vb1h182k panasonic r3 resistor 16k, 1% 1 any r8 resistor 1.24k, 1% 1 any r9 resistor 1k, 1% 1 any r2,4,6,7 resistor 0 ohm 4 any r1,5,10 resistor not used 3 c6,7 capacitor not used 2 d1 diode not used 1 j1,j2 socket scope probe 2 131-5031-00 tektronix jp1,jp2 terminal wire connect 2 ed1973-nd digi-key ju1 terminal 2-pin header 1 s1012-02-nd digi-key 5 downloaded from: http:///
rev1.0 4/29/2005 IRDC3637eval typical operating waveforms test conditions: vcc=vin=5v, vc=12v, vout=1.8v, iout =0-7a, ta=room temp, no air flow. unless otherwise specified. 6 figure 4 - start up waveforms ch1: vin=vcc, ch2: vc, ch3: vss, ch4: vout figure 5 - start up waveforms ch1: vin=vcc, ch2: vc, ch3: vss, ch4: vout figure 6 - gates waveforms ch1: hdrv, ch2ldrv,, ch4:inductor current iload=5a figure 7 - gates waveforms ch1: hdrv, ch2ldrv,, ch3:inductor point iload=5a downloaded from: http:///
rev1.0 4/29/2005 IRDC3637eval typical operating waveforms test conditions: vcc=vin=5v, vc=12v, vout=1.8v, iout =0-7a, ta=room temp, no air flow. unless otherwise specified. figure 8 - shutdown by shorting the ss pin ch1: hdrv, ch2ldrv,, ch3:ss iload=5a figure 9 - output voltage ripple ch1: vout, ch4: inductor current iload=5a figure 10 - load transient (0-5a) ch1: vout, ch4: step load current figure 11 - load transient (5-0a) ch1: vout, ch4: step load current downloaded from: http:///
rev1.0 4/29/2005 IRDC3637eval typical performanmce curves test conditions: vcc=vin=5v, vc=12v, vout=1.8v, iout =0-7a, ta=room temp, no air flow. unless otherwise specified. efficiency vc=12v, vcc=vbus=5v, iout=0-8a, fs=400khz 0 10 20 30 40 50 60 70 80 90 100 0123456789 iout (a) efficiency (%) figure 12 - efficiency using irf8910 dual mosfet ir world headquarters: 233 kansas st., el segundo, califor nia 90245, usa tel: (310)252-7105 tac fax: (310) 252-7903 visit us at www.irf.com for sales contact information data and specification subject to change without notice. 02/01 this product has been designed and qualified for the industrial market. downloaded from: http:///
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