ev2108dq/dk-00a 2a, 6v, 720khz synchronous buck converter evaluation board ev2108dq/dk-00a rev. 1.0 www.monolithicpower.com 1 3/2/2006 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2006 mps. all rights reserved. the future of analog ic technology tm tm description the ev2108dq/dk-00a is the evaluation board for the mp2108, a 2a, 720khz synchronous buck converter designed for low voltage applications requiring high efficiency. the mp2108 is capable of providing an output voltage as low as 0.9v and integrates top and bottom switches to minimize power loss and component count. the 720khz switching frequency reduces the size of filtering components for a small solution size. the mp2108 includes cycle-by-cycle current limiting and under voltage lockout. the 10-pin msop package is available on the EV2108DK-00A while the 10-pin 3mm x 3mm qfn package is available on the ev2108dq-00a. electrical specifications parameter symbol value units input voltage v in 2.6 ? 6 v output voltage v out 1.8 v output current i out 2 a features ? 2a output current ? input voltage range of 2.6v to 6v ? over 90% efficiency applications ? soho routers, pcmcia cards, mini pci ? handheld computers, pdas ? cell phones, digital still and video cameras ? small lcd displays ?mps? and ?the future of analog ic technology? are registered trademarks of monolithic power systems, inc. ev2108dq/dk-00a evaluation board dimensions (2.5?x x 2.0?y x 0.5?z) board number mps ic number ev2108dq/dk-00a mp2108dq/dk
ev2108dq/dk-00a ? 2a, 6v, 720khz synchronous buck converter evaluation board ev2108dq/dk-00a rev. 1.0 www.monolithicpower.com 2 3/2/2006 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2006 mps. all rights reserved. tm evaluation board schematic mp2108 u1 lx vin bst 1 3 7 4 5 9 8 6 10 2 fb comp ss pgnd sgnd vref run vout vout vin gnd ev2108_s01 c7 10nf c1 ns c6 ns c11 ns c3 10nf d1 1n5819 d2 opt. d3 opt. c5 3.3nf c10 10nf r5 ns c4 ns c9 ns vin gnd en ev2108dq/dk-00a bill of materials qty ref value description package manufacturer manufacturer p/n 5 c1, c4, c6, c9, c11 ns not stuffed 1 c2 10f ceramic cap, 10v, x5r sm1210 tdk c3225x5r1a106k 3 c3, c7, c10 10nf ceramic cap, 50v, x7r sm0805 tdk c2012x7r1h103k 1 c5 3.3nf ceramic cap, 50v, x7r sm0805 panasonic ecj-2vb1h332k 1 c8 22f ceramic cap, 6.3v, x5r sm1210 tdk c3225x5r0j226m 1 d1 schottky diode, 40v, 1a sod123 diodes inc 1n5819hw-7 2 d2, d3 do not stuff 1 l1 5h inductor, 2.2a smd sumida cdrh6d26-5r0 1 r1 100k ? resistor, 5% sm0805 panasonic erj-6geyj104v 1 r2 6.8k ? resistor, 5% sm0805 panasonic erj-6geyj682v 2 r3, r4 10k ? resistor, 1% sm0805 panasonic erj-6enf1002v 1 r5 ns not stuffed 1 u1 dc-dc converter msop10/ qfn10 mps mp2108dq/dk
ev2108dq/dk-00a ? 2a, 6v, 720khz synchronous buck converter evaluation board ev2108dq/dk-00a rev. 1.0 www.monolithicpower.com 3 3/2/2006 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2006 mps. all rights reserved. tm printed circuit board layout figure 1?top silk layer figure 2?top layer figure 3?bottom layer
ev2108dq/dk-00a ? 2a, 6v, 720khz synchronous buck converter evaluation board notice: the information in this document is subject to change wi thout notice. please contact mps for current specifications. users should warrant and guarantee that third party intellectual property rights ar e not infringed upon when integrating mps products into any application. mps will not assume any legal responsibility for any said applications. ev2108dq/dk-00a rev. 1.0 www.monolithicpower.com 4 3/2/2006 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2006 mps. all rights reserved. tm quick start guide the output voltage of this board is set to 1.8v. the board layout accommodates most commonly used inductors and output capacitors. 1. attach the positive and negative ends of the load to the vout and gnd pins, respectively. 2. attach the input voltage (2.6v v in 6v) and input ground to the in and gnd pins, respectively. 3. a pull-up resistor has connected the run pin to the vin pin, so the mp2108 will startup automatically without applying an external voltage to the run pin. 4. the output voltage v out can be changed by varying r3. calculate the new value using the formula: ) 1 v v ( 4 r 3 r fb out ? = where v fb = 0.9v and r4 = 10k ? . for example, for v out = 2.5v: ? ? = ? ? = ? = k 8 . 17 ~ k 78 . 17 ) 1 v 9 . 0 v 5 . 2 ( k 10 ) 1 v v ( 4 r 3 r fb out for the closest standard 1% value. see maximum duty cycle limits to determine allowable output voltages. the optional bootstrap diode (d3) may be added for improved efficiency.
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