1 application note 1574 ISL85033DUALEVAL1Z wide vin dual standard buck regulator with 3a/3a output current description the ISL85033DUALEVAL1Z kit is intended for use by individuals with requirements for point-of-load applications sourcing from 4.5v to 28v. the ISL85033DUALEVAL1Z evaluation board is used to demonstrate the performance of the isl85033 wide vin dual standard buck regulator with 3a/3a output current converter. the isl85033 is offered in a 4mmx4mm 28 ld tqfn package with 1mm maximum height. the complete converter occupies 6.25cm 2 area. key features ? wide input voltage range from 4.5v to 28v ? adjustable output voltage with continuous output current up to 3a ? current mode control ? adjustable switching frequency from 300khz to 2mhz ? independent power-good detection ? selectable in-phase or out-of-phase pwms switching operation ? independent, sequential, ratiometric or absolute tracking between outputs ? internal 2ms soft-start time ? overcurrent and hiccup mode short circuit protection, thermal overload protection, uvlo ? boot undervoltage detection ? channels are out-of-phase, reducing voltage ripple and component size recommended equipment the following materials are recommended to perform testing: ? 0v to 30v power supply with at least 7a source current capability or 5v battery ? electronic loads capable of sinking current up to 7a ? digital multimeters (dmms) ? 100mhz quad-trace oscilloscope ?signal generator quick setup guide 1. ensure that the circuit is correctly connected to the supply and loads prior to applying any power. 2. connect the bias supply to vin1, the plus terminal to vin1 and the negative return to gnd2. 3. verify that the position is on for s1 and s2. 4. turn on the power supply. 5. verify the output voltage is 5v for v out1 and 3.3v for v out2. evaluating the other output voltage the ISL85033DUALEVAL1Z kit outputs are preset to 5v for v out1 and 3.3v for v out2 ; however, output voltages can be adjusted from 0.8v to 5v. the output voltage programming resistor, r3 (or r14 in channel 2), will depend on the desired output voltage of the regulator and the value for the feedback resistor r2 (r16 respectively), as shown in equation 1. if the output voltage desired is 0.8v, then r3 (r14 respectively) is shorted. the value for r2 (r16 respectively) is typically between 1k and 10k. please note that if vout is less than 2.5v, the switching frequency and compensation must be changed for 300khz operation due to minimum on-time limitation. please refer to the data sheet for further information ( fn6676) . frequency control isl85033 has an fs pin that controls the frequency of operation. programmable frequency allows for optimization between efficiency and external component size. default switching frequency is 500khz when fs is tied to vcc (r 9=0). by removing r9 and connecting r10 to ground, the switching frequency could be changed from 300khz (r10 = 383k) to 2mhz (r10 = 40.2k). please refer to the data sheet ( fn6676 ) for calculating the value of r10. do not leave this pin floating. (eq. 1) r3 v out1 ( v fb ) r2 v fb ? ? ? = r14 v out2 ( v fb ) r16 v fb ? ? ? = caution: these devices are sensitive to electrostatic discharge; follow proper ic handling procedures. copyright intersil americas inc. 2010. all rights reserved. 1-888-intersil or 1-888-468-3774 | intersil (and design) is a trademark owned by in tersil corporation or one of its subsidiaries. all other trademarks mentioned are the property of their respective owners. november 29, 2010 an1574.2 author: paul orfanu
2 an1574.2 november 29, 2010 disabling/enabling function the isl85033 evaluation board contains s1, s2 switches to enable or disable each of the channels, thus allowing low quiescent current state. table 1 details this function. if en1 or en2 are floating, then the outputs will start in the sequencing described in the data sheet section on output sequencing and also summarized in table 2. sync control the isl85033 evaluation board has an si pin that allows external synchronization freque ncy to be applied. default board configuration has r18 = 0 to gnd, which defaults to the internal selected switching frequency. removing r18 allows the synchronization to be external between 600khz to 4mhz. do not leave this pin floating. table 1. switch settings s1 s2 on/off control on off enable v out1; disable v out2 off on disable v out1; enable v out2 on on enable v out1; enable v out2 off off disable v out1; disable v out2 table 2. en1 en2 v out1 v out2 note high floating first after v out1 > 90% floating high after v out2 >90% first high high same time as v out2 same time as v out1 floating floating not allowed application note 1574
3 an1574.2 november 29, 2010 ISL85033DUALEVAL1Z schematic dnp b340b dnp on open off off open on dnp dnp dnp dnp vout1=5v vout2=3.3v b340b sgnd 26 boot1 d3 pgood1 fs 24 20 ss2 boot2 open l2 7uh vin2 ss1 vout1 r12 dnp r13 dnp vcc 15 17 21 comp2 c15 12pf r11 19 18 comp1 c13 12pf 2 3 r5 fb1 gnd3 4.7uf fb2 ss1 d1 l1 r15 vout2 25.5k 42.2k c4 470pf 10uf c7 en2 boot1 r3 0.01uf en1 vin1 r20 10uf c18 c6 10uf d2 boot1 10 vout1 470pf vcc 47uf 11 12 13 14 8.06k r16 vo2 jlx2 gnd4 69.8k 27 pgood2 ss1 8.06k 68pf c16 0 c1 68pf ss2 jvo2 9 29 r2 pgood2 47uf 7uh open r1 0 jlx1 vout1 isl85033irtz 1 c14 dnp c12 c17 en2 d4 boot2 r23 6 22 vin2 vout2 dnp d6 syncin r10 r8 c2 ext_5v r27 r26 dnp boot2 d5 ss2 s1 en1 en2 vo1 vcc vcc r19 c3 en1 dnp fs s2 5 4 c5 7 pgood1 16 c11 jvo1 25 dnp fb2 c10 r21 r14 c9 r6 r4 r22 r24 r25 r17 c8 r7 r18 r9 pg2 so si fs gnd gnd2 vin1 gnd1 8 28 23 u1 syncin ss1 100k 100k dnp dnp dnp vout2 comp2 ss2 vin2 0 dnp 0 comp1 dnp vout2 0 vin1 fb1 vcc 0 0 0.01uf vout1 69.8k pg1 ep ss1 pgnd1 phase1 pgood1 nc fs syncin sgnd syncout pgood2 comp2 fb2 ss2 pgnd2 boot2 phase2 phase2 vin2 vin2 en2 vcc en1 vin1 vin1 phase1 fb1 boot1 comp1 a a a a a a a a a a a a a a a a a a a aa a a a a a a a aa a a a application note 1574
4 an1574.2 november 29, 2010 table 3. bill of materials part number qty units reference designator description manufacturer manufacturer part # isl85033eval1zrevbpcb 1 ea see label-rename board pwb-pcb, isl85033eval1z, revb, rohs tbd isl85033eval1zrevbpcb eee-fk1v101p-t 0 ea dnp (c2, c12) cap, smd, 8x10.2, 100f, 35v, 20%, al.el., rohs panasonic eee-fk1v101p gmk325bj106kn-t 2 ea c6, c8 cap, smd, 1210, 10f, 35v, 10%, x5r, rohs taiyo yuden gmk325bj106kn-t h1044-00120-50v5-t 2 ea c13, c15 cap, smd, 0402, 12pf, 50v, 5%, npo, rohs avx 04025c120jat venkel c0402c0g500-120jne h1044-00680-50v5-t 2 ea c1, c16 cap, smd, 0402, 68pf, 50v, 5%, npo, rohs murata grm36cog680j050aq panasonic ecj-0ec1h680j venkel c0402cog500-680jne h1045-00103-50v10-t 2 ea c5, c9 cap, smd, 0603, 0.01f, 50v, 10%, x7r, rohs murata grm39x7r103k050 avx 06035c103kat2a venkel c0603x74500-103kne h1045-00471-50v5-t 2 ea c4, c10 cap, smd, 0603, 470pf, 50v, 5%, npo, rohs panasonic ecj-1vc1h471j venkel c0603cog500-471jne h1045-00475-6r3v10-t 1 ea c7 cap, smd, 0603, 4.7f, 6.3v, 10%, x5r, rohs venkel c0603x5r6r3-475kne tdk c1608x5r0j475k panasonic ecj-1vb0j475k murata grm188r60j475ke19d kemet c0603c475k9pactu taiyo yuden jmk107bj475ka-t h1045-dnp 0 ea c3, c11 cap, smd, 0603, dnp-place holder, rohs h1082-00106-50v10-t 1 ea c18 cap, smd, 1210, 10f, 50v, 10%, x5r, rohs taiyo yuden umk325bj106km-t h1082-00476-16v20-t 2 ea c14, c17 cap, smd, 1210, 47f, 16v, 20%, x5r, rohs tdk c3225x5r1c476m panasonic ecj-4yb1c476m murata grm32er61c476me15l taiyo yuden emk325bj476mm-t kemet c1210c476m4pactu venkel c1210x5r160-476mne sql004 2 ea l1, l2 coil-pwr inductor, smd, 10mm, 7h, 25%, 4.8a, rohs falco sql004 131-4353-00 4 ea jlx1, jlx2, jvo1, jvo2 conn-scope probe test pt, compact, pcb mnt, rohs tektronix 131-4353-00 application note 1574
5 an1574.2 november 29, 2010 1514-2 8 ea vo1, vo2, gnd1- gnd4, vin1, vin2 conn-turret, terminal post, th, rohs keystone 1514-2 5002 11 ea a) fs, si, so, en1, en2, gnd, pg1, pg2 conn-mini test point, vertical, white, rohs keystone 5002 5002 0 ea b) ss1, ss2, ext_5v conn-mini test point, vertical, white, rohs keystone 5002 b340b-13-f-t 2 ea d1, d2 diode-schottky, smd, smb, 2p, 40v, 3a, rohs diodes inc. b340b-13-f isl85033irtz 1 ea u1 ic-3a dual std regulator, 28p, tqfn, 4x4, rohs intersil isl85033irtz h2505-dnp 0 ea r10, r17, r19, r20, r23-r27 resistor, smd, 0603, 0.1%, mf, dnp-place holder h2510-00r00-1/16w-t 2 ea r1, r15 res, smd, 0402, 0 , 1/16w, 5%, tf, rohs venkel cr0402-16w-00t panasonic erj-2ge0jr00 h2510-02552-1/16w1-t 1 ea r14 res,smd, 0402, 25.5k, 1/16w, 1%, tf, rohs venkel cr0402-16w-2552ft panasonic erj-2rkf2552x vishay/dale crcw040225k5fked stackpole rmc 1/16s 25.5k 1% r h2510-04222-1/16w1-t 1 ea r3 res,smd, 0402, 42.2k, 1/16w, 1%, tf, rohs panasonic erj-2rkf4222x venkel cr0402-16w-4222ft h2510-08061-1/16w1-t 2 ea r2, r16 res, smd, 0402, 8.06k, 1/16w, 1%, tf, rohs venkel cr0402-16w-8061ft panasonic erj-2rkf8061x rohm mcr01mzpf8061 yageo rc0402fr-078k06l vishay/dale crcw04028k06fked h2511-00r00-1/10w-t 4 ea r7-r9, r18 res, smd, 0603, 0 , 1/10w, tf, rohs venkel cr0603-10w-000t rohm mcr03ezpj000 panasonic erj-3gey0r00v yageo rc0603jr-070rl vishay/dale crcw06030000z0ea h2511-01004-1/10w1-t 2 ea r4, r6 res, smd, 0603, 1m, 1/10w, 1%, tf, rohs panasonic erj-3ekf1004v venkel cr0603-10w-1004ft yageo rc0603fr-071ml rohm mcr03ezpfx1004 koa rk73h1jttd1004f vishay/dale crcw06031m00fkea table 3. bill of materials (continued) part number qty units reference designator description manufacturer manufacturer part # application note 1574
6 an1574.2 november 29, 2010 h2511-06982-1/10w1-t 2 ea r5, r11 res, smd, 0603, 69.8k, 1/10w, 1%, tf, rohs venkel cr0603-10w-6982ft yageo rc0603fr-0769k8l vishay/dale crcw060369k8fkea koa rk73h1jttd6982f h2511-dnp 0 ea r12, r13 res, smd, 0603, dnp-place holder, rohs h2514-00r00-1/4w-t 1 ea r22 res, smd, 1210, 0 , 1/4w, tf, rohs venkel cr1210-4w-000 h2514-dnp 0 ea r21 res, smd, 1210, d n p, d n p, d n p, t f, rohs gt13mcbe 2 ea s1, s2 switch-toggle, thru-hole, 5pin, spdt, 3pos, on- off-on, rohs c&k components gt13mcbe sj-5003-black 4 ea bottom four corners bumpons, 0.44? w x 0.20? h, dometop, black 3m sj-5003spbl 5x8-static-bag 1 ea place assy in bag bag, static, 5x8, ziploc, rohs intersil 212403-013 dnp 0 ea d3-d6 do not populate or purchase label-rename board 1 ea rename pcb to: ISL85033DUALEVAL1Z label, to rename board intersil label-rename board label-serial number 1 ea label, for serial number and bom rev # table 3. bill of materials (continued) part number qty units reference designator description manufacturer manufacturer part # application note 1574
7 an1574.2 november 29, 2010 ISL85033DUALEVAL1Z board layout figure 1. top layer components figure 2. top layer etch application note 1574
8 an1574.2 november 29, 2010 figure 3. second layer etch figure 4. third layer etch ISL85033DUALEVAL1Z board layout (continued) application note 1574
9 intersil corporation reserves the right to make changes in circui t design, software and/or specifications at any time without n otice. accordingly, the reader is cautioned to verify that the application note or technical brief is current before proceeding. for information regarding intersil corporation and its products, see www.intersil.com an1574.2 november 29, 2010 figure 5. bottom layer etch figure 6. bottom layer components ISL85033DUALEVAL1Z board layout (continued) application note 1574
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