ev28114dg-00a 600ma synchronous buck step-down converter ev28114dg-00a rev. 1.0 www.monolithicpower.com 1 9/20/2011 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. the future of analog ic technology description the ev28114 evaluation board is designed for low dropout step down converter applications. it implements the mp28114 1.7mhz fixed frequency, current mode, pwm step-down converter. the device integrates a main switch and a synchronous rectifier for high efficiency without an external schottky diode. it is ideal for powering portable equipments that runs from a single cell lithium-ion (li+) battery. it can supply 600ma of load current from a 2.5v to 6v input voltage. the output voltage can be regulated as low as 0.6v. in 100% duty cycle dropout operation, it works with minimum input voltage as low as output voltage. electrical specifications parameter symbol value units input voltage range v in 2.5 ? 6.0 v output voltage v out 1.8 v load max i out 600 ma features ? high efficiency: up to 95% ? 600ma available load current ? 2.5v to 6v input voltage range ? output voltage as low as 0.6v ? 100% duty cycle in dropout ? short circuit protection ? thermal fault protection ? <0.1 a shutdown current ? programmable enable control applications ? cellular and smart phones ? microprocessors/dsp core supplies ? pdas ? mp3 players ? digital still and video cameras ? portable instruments ?mps? and ?the future of analog ic technology? are registered trademarks of monolithic power systems, inc. ev28114dg-00a evaluation board dimensions (2.5?x x 2.5?y x 0.5?z) board number mps ic number ev28114dg-00a MP28114DG
ev28114dg-00a ? 600ma synchronous buck step-down converter ev28114dg-00a rev. 1.0 www.monolithicpower.com 2 9/20/2011 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. evaluation board schematic c3 ns r3 ns c5 ns gnd vin vout en gnd u1 6,8 4 7 5 1 fb sw mp28114 en c4 ns in ev28114dg-00a bill of materials qty ref value description package manufacturer manufacturer p/n 1 c1 4.7uf ceramic cap., 10v, x5r sm0805 tdk c2012x5r1a475k 1 c2 10uf ceramic cap., 6.3v, x5r sm0805 kyocera cm21x5r106k06at 3 c3,c4, c5 do not stuff 1 l1 2.2uh 1.63a smd toko d52lc-#a914byw-2r2m 1 r1 300k ? film res., 1% sm0603 yageo rc0603fr-07300kl 1 r2 150k ? film res., 1% sm0603 yageo rc0603fr-07150kl 1 r3 do not stuff 1 u1 dc-dc converter qfn8 mps MP28114DG
ev28114dg-00a ? 600ma synchronous buck step-down converter ev28114dg-00a rev. 1.0 www.monolithicpower.com 3 9/20/2011 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. printed circuit board layout figure 1?top silk layer figure 2?top layer figure 3?bottom layer
ev28114dg-00a ? 600ma synchronous buck step-down converter notice: the information in this document is subject to change wi thout notice. please contact m ps 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. ev28114dg-00a rev. 1.0 www.monolithicpower.com 4 9/20/2011 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. quick start guide (adjustable output) the default 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 (2.5v v in 6v) and input ground to the vin and gnd pins, respectively. 3. to enable the mp28114 apply a voltage, 1.5v v en 6v, to the en pin. to disable the mp28114 apply a voltage, v en < 0.3v, to the en pin. a 100k ? resistor can be set in r3 to connect the en pin to the in pin, so the part will operate without applying any external voltage to the en pin. 4. the output voltage v out can be changed by varying r2. calculate the new value by formula: 1 v v 1 r 2 r fb out ? ? ? ? ? ? ? ? ? = where v fb = 0.6v and r1 = 300k ? . example: for v out = 1.8v: = ? ? ? ? ? ? ? = k v v k r 150 1 6 . 0 8 . 1 300 2 therefore, use a 150k ? standard 1% value. quick start guide (modification for fixed output) for modifying the ev28114dg-00a to accommodate a fixed output voltage version of the mp28114: 1. verify that a fixed output version of the mp28114 chip is on the evaluation board. refer to mp28114 datasheet for fixed voltage package codes. 2. remove both r1 and r2. 3. short r1 while leaving r2 open. 4. attach the positive and negative ends of the load to the vout and gnd pins, respectively. 5. attach the input voltage (2.5v v in 6v) and input ground to the vin and gnd pins, respectively. 6. to enable the mp28114 apply a voltage, 1.5v v en 6v, to the en pin. to disable the mp28114 apply a voltage, v en < 0.3v, to the en pin. the default setting for the jumper j1 on the board connects v in to the en pin. in this configuration, the part will operate without applying any external voltage to the en pin.
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