ev2905ek-00a 12a,3~28v,300khz,hysteretic synchronous step-down controller evaluation board ev2905ek-00a rev. 1.0 www.monolithicpower.com 1 5/5/2011 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. the future of analog ic technology description the ev2905ek-00a is the evaluation board for the MP2905EK, a hysteretic synchronous step- down controller. it offers a very compact solution to achieve 1.8v, 12a continuous output current over a wide operation input voltage. an adjustable soft-start prevents inrush current at turn-on. hysteretic voltage control can provide fast transient without any loop compensation. full protection features include ocp, output ovp, thermal shut down. the ev2905ek frequency is about 300khz (12v input). the efficiency is up to 90% (12v input) with the supplied components. electrical specifications parameter symbol value units input voltage v in 12 (1) v output voltage v out 1.8 v hold current i out 12 a notes: circuit can work up to about 12a over a wide input voltage range. this evb shows the performance at 12v input. so the frequency and current limit are des igned for the 12v application. features ? 12a output current,1.8v output voltage ? programmable soft-start ? hiccup current limit and thermal shut down applications ? motherboard power supplies ? agp and pci-express power supplies ? graphic-card power supplies ? set-top boxes ? point-of-load power supplies ?mps? and ?the future of analog ic technology? are registered trademarks of monolithic power systems, inc. ev2905ek-00a eval uation board (l x w x h) 2.5? x 2.5? x 0.63? (6.3cm x 6.3cm x 1.6cm) board number mps ic number ev2905ek-00a MP2905EK i out (a) efficiency (%) efficiency 0 10 20 30 40 50 60 70 80 90 100 036912
ev2905ek-00a hysteretic synchronous step-down controller ev board ev2905ek-00a rev. 1.0 www.monolithicpower.com 2 5/5/2011 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. evaluation board schematic
ev2905ek-00a hysteretic synchronous step-down controller ev board ev2905ek-00a rev. 1.0 www.monolithicpower.com 3 5/5/2011 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. ev2905ek-00a bill of materials qty ref value description package manufacturer manufacturer p/n 2 c1a, c1b 4.7uf ceramic cap, 50v,x7r 1210 murata grm32er71h475ka88l 4 c1d, c2d, c6, c7 100nf ceramic cap, 50v,x7r 0603 murata grm188r71h104ka93d 2 c2a, c2b 100uf ceramic cap, 6.3v,x5r 1210 murata grm32er60j107me20l 1 c1c 220uf electrolytic, 35v elc smd jiang hai vtd-35v220 1 c2c 330uf poscap, 6.3v poscap sanyo 6tpe330mil 2 c3,c5 10nf ceramic cap, 50v,x7r 0603 murata grm188r71h103ka01d 1 c4 4.7uf ceramic cap, 16v,x5r 0805 murata grm21br61c475ka88l 1 c8 3.9nf ceramic cap, 50v,x7r 0603 murata grm188r71h392ka01d 1 c9 22nf ceramic cap, 50v,x7r 0603 murata grm188r71h223ka01d 1 c10 1uf ceramic cap, 16v,x7r 0603 murata grm188r71c105ka12d 1 r1 12.7k film res,1% 0603 yageo rc0603fr-0712k7l 1 r2 6.04k film res,1% 0603 yageo rc0603fr-076k04l 1 r3 3k film res,1% 0603 yageo rc0603fr-073kl 3 r4, r5 ns 0603 1 r7 20k film res,5% 0603 any 2 r8, r13 10 film res,1% 0603 yageo rc0603fr-0710rl 3 r6, r9, r10, r11 0 film res,5% 0603 any 1 r12 2 film res,5% 0603 any 1 q1 si7112dn, 30v, 17a, 8.2m ? @4.5vgs powerpak 1212-8 vishay si7112dn-t1-e3 1 q2 si7658adp, 30v,36a, 2.8m ? @4.5vgs powerpak so-8 vishay si7658adp-t1-ge3 1 q3 2n7002 (60v,115ma) sot-23 diodes 2n7002(60v,115ma) 1 d1 b0540w 40v,0.5a sod-123 diodes b0540w 1 d2 b0520lw-7-f 20v 0.5a sod-123 diodes b0520lw-7-f 1 l1 1.5uh inductor, isat=24a, dcr=2.8m ? smt toko fdu1250c-1r5m 1 u1 mp2905 msop10 mps MP2905EK
ev2905ek-00a hysteretic synchronous step-down controller ev board ev2905ek-00a rev. 1.0 www.monolithicpower.com 4 5/5/2011 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. printed circuit board layout figure 1?top layer figure 2?in1 layer figure 3?in2 layer figure 4?bottom layer
ev2905ek-00a hysteretic synchronous step-down controller ev board notice: the information in this document is subject to change wi thout notice. users should warra nt and guarantee that third party intellectual property rights are not infringed upon w hen integrating mps products into any application. mps will not assume any legal responsibility for any said applications. ev2905ek-00a rev. 1.0 www.monolithicpower.com 5 5/5/2011 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. quick start guide 1. connect the positive terminal of the load to vout pin, and the negative terminal of the load to gnd pin. 2. preset the power supply output to 12v and turn off the power supply. 3. connect the positive terminal of the power supply output to the vin pin and the negative terminal of the power supply output to the gnd pin. 4. turn the power supply on. the MP2905EK will automatically startup. 5. to use the enable function, apply an input to en pin. drive en higher than 3v to turn on the mos q3, then ss is pulled down, part shuts down. drive en less than 0.5v to turn off the mos q3, then ss is released, part turns on. and at no load condition, a dummy load which is less than 10k ? is needed at output terminal to consume the bst leakage current. 6. the output voltage vout can be programmed by r1 and r2. calculate the new value using the formula: ) 1 ) 5 . 0 ( 01 . 0 ( * 2 1 ? + + = fb load dc v i r v vout r r where v fb =0.59v, r dc is the dc resistance of the output inductor, i load is the full load current. r2 is for approximately 50ua to 150ua bias current in the resistor-divider. and the frequency will be influenced by r1 and r2 value. so please refer to ds to set the frequency. 7. the ev board is designed for 12v input. so, for other input voltage, some parameters such as current limit and frequency need to be redesigned. please refer to ds to set related parameters.
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