MP2012 low voltage, 2.7-6v input,1.5a, 1.2mhz sy nchronous step -down converter MP2012 rev. 1. 01 www.monolithicpower.com 1 9/22/2011 mps proprietar y information. pate nt protec ted. un authorized photo c op y and d uplication prohibited. ? 2011 mps. all rights reserved. the future of analog ic technology descri ption the MP2012 is a fu lly integrated, internally compensated 1.2mhz fixed frequency pwm step-down converter. it is idea l f o r powering portable eq uipment that runs from a single cell lithium-ion (li+) battery, with an input range from 2.7v to 6v. the MP2012 can provide up to 1.5a of load current wit h output voltage as low as 0.8v. it can also ope rate at 100 % duty cycle for low drop out applications. with p eak current mode control and internal compensation, the MP2012 is stable with ceramic cap a citors and small indu ctors. fault conditio n protection includes cy cle-by-cycle current limiting and thermal shutdown. MP2012 is available in a small qfn6 (3x3 mm ) package. features ? 2.7-6v input operation range ? output adjustable from 0.8v to vin ? 1 a max sh utdown current. ? up to 95% efficiency ? 100% duty cycle for low dropout applications ? 1.2mhz fixed switchin g frequency ? stable with low esr output ceramic capacitors ? thermal sh utdown ? cycle-by-cycle over cu rrent protection ? short circuit protection ? available in qfn6 (3 x3mm) appli c ations ? dvd+/-r w drives ? smart phon es ? pdas ? digital cameras ? portable instruments for mps g reen sta t us, plea se v i sit mp s w ebsite under q uality assuran c e . ?mp s ? and ?th e fu ture o f a nal og ic t e chno lo gy ? are t r a dem ar ks o f m o n o li thi c pow e r sy stem s, i n c. typical application MP2012 pvi n vi n gn d en sw fb 1 2 3 6 4 5 c1 v in 2.7v to 6v en l1 r1 r2 rt c2 v ou t 1. 8v / 1 . 5 a e f f i cie n cy v s . loa d c ur r e nt loa d c u r r e n t(a ) e ffi c i e n c y (%) 0 10 20 30 40 50 60 70 80 90 100 0 0 .3 0 .6 0 .9 1 .2 1 .5 vin=5v vi n = 3 v http://
MP2012 ? 1.5a synchronous step-dow n converter MP2012 rev. 1. 01 www.monolithicpower.com 2 9/22/2011 mps proprietar y information. pate nt protec ted. un authorized photo c op y and d uplication prohibited. ? 2011 mps. all rights reserved. ordering information part number* package top marking free air temperature (t a ) MP2012dq qfn6(3x3mm) 9e ?40 c to +85 c * for tape & reel, add suffix ?z (e.g. MP2012dq?z). for rohs compliant packaging, add suffix ?lf (e.g. MP2012dq?lf?z) package reference t op view exposed pad connected to gnd fb gnd sw 1 2 3 en vin pvin 6 5 4 absolute m a xi mum ratings (1) pvin, vin t o gnd...................... ?0.3v to + 6.5v sw to gnd .......................... ?0.3v to v in + 0.3v en, fb to gnd ........................... ?0.3v to +6.5v operating temperature............. ?40c to +85c continuous power dissipation (t a = +25c) (2) ??????????????????....2.5 w junction te mperature ............................... 150c lead temperature .................................... 260c storage temperature ............. ?65c to +150c recommended operating conditions (3) supply voltage v in ............................. 2.7v to 6v operating junct. temp (t j ) ..... ?40c to +125c thermal resistance (4) ja jc qfn6 (3 x3mm) ....................... 50 ...... 12 ... c/w notes : 1) exceeding these ratings ma y da m age the device. 2) the ma ximum allowable po w e r dissipation is a fun c tion of the maximum junction temperatu r e t j (max), the junction-to- ambient therm a l resistance ja , a nd the a m bient t e mperatu r e t a . the maximu m allow a ble con t inuous po w e r di ssipation at an y ambient te mperatu r e is ca lculated by p d (max) = (t j (max)-t a )/ ja . exceeding the maximum allowable powe r dissipation w ill cause ex cessive die tempe r ature, and t h e regulator w ill g o into thermal shutdo w n . inte rnal thermal shutdo w n circuitr y pr otects the device from permanent damage. 3) the device is not guarant eed to function outside of its operating conditions. 4) measured on jesd51-7, 4-layer pcb.
MP2012 ? 1.5a synchronous step-dow n converter MP2012 rev. 1. 01 www.monolithicpower.com 3 9/22/2011 mps proprietar y information. pate nt protec ted. un authorized photo c op y and d uplication prohibited. ? 2011 mps. all rights reserved. electri c al characteristi cs (5) v in = v en = 3.6v, t a = + 2 5 c, unles s otherw ise noted. parameters conditio n min t y p max units supply cu rre nt v en_ = v in , v fb = 0.9v 600 750 a shutdown cu rre nt v en_ = 0v , v in = 6v 0.01 1 a therm a l shut down trip th reshol d hysteresi s = 20 c 150 c en trip th re shol d -40 c t a +85 c 0.3 1.0 1.5 v en input cu rrent v en = 0v 0.1 1.0 a en input cu rrent v en = 6v 6 a in und e rvolta ge lo ckout thre s hol d risi ng edge 2.15 2.40 2.65 v in und e rvolta ge lo ckout hystere s is 160 mv reg u lated fb voltage t a = +25 c -40 c t a +85 c 0.784 0.776 0.800 0.800 0.816 0.824 v fb input bias current v fb = 0.8v -50 -2 +50 na sw pfet on res i s t anc e i sw = 100ma 0.18 0.25 0.28 ? s w nfe t on resi st an ce i sw = -10 0 ma 0.14 0.2 0.24 ? sw l e a k a ge c u rr en t v en =0v ; v in =6v v sw _ =0v -1 0.1 1 a sw l e a k a ge c u rr en t v en =0v ; v in =6v v sw _ =6v -5 1.5 5 a sw pfet peak current li mit duty cy cle = 1 00% duty cy cle = 5 0 % (6) 2.1 3.0 3.5 a switchin g fre quen cy 1.0 1.2 1.4 mhz notes : 5) production test at +25c. specificat ions over the temperature range are gua ranteed by design and characterization. pin functio n s pin # nam e des c ription 1 fb feedb ack inp u t. a n external resi stor divider from the output to gnd, tapped to the fb pin sets the output voltage. 2 gnd, exposed pa d ground pin. connect exposed pad to grou nd plane f o r proper t hermal performance. 3 sw switch node to the inductor. 4 pvin input supply pin for power fet. 5 vin input supply pin for controller. put small decoupling ceramic near this pin. 6 en enable input, ?high? enables MP2012. en is pulled to gnd with 1meg internal resistor.
MP2012 ? 1.5a synchronous step-dow n converter MP2012 rev. 1. 01 www.monolithicpower.com 4 9/22/2011 mps proprietar y information. pate nt protec ted. un authorized photo c op y and d uplication prohibited. ? 2011 mps. all rights reserved. typical perfo r manc e characteristics v in = 5v, v out = 1.8v, l=3.3uh, t a = +25oc, unless otherwise noted. lo a d regulation enable supply current vs. input voltage 500 550 600 650 700 750 800 850 2.5 3 3.5 4 4.5 5 5.5 6 v in (v ) c a se t em p er a t u r e r i sev s. ou t p u t c u r r e n t 0 5 10 15 20 25 30 35 0 0 .5 1 1 .5 o u tput c u r r e n t (a ) d uty cycle peak c u rren t vs. d u t y li ne r e gul a t i on l oad r e g u l a t i o n l oad current(a) i nput v o l t a g e (v ) li ne r e gul a t i on -0.4% -0.3 % -0.2 % -0.1 % 0.0% 0.1 % 00 . 5 11 . 5 peak cu rren t(a) - 0. 60% - 0. 40% - 0. 20% 0. 00% 0. 20% 0. 40% 2 2 .5 3 3 .5 4 4 .5 5 5 .5 6 io=0a i o = 0 .75a i o = 1.5a vin=3v vin=5v e f f i cie n cy v s. loa d c ur r e nt loa d c u r r e nt(a ) e ffi c i e n c y (%) 0 10 20 30 40 50 60 70 80 90 100 0 0 .3 0 .6 0 .9 1 .2 1 .5 vin= 5 v vi n =3v 1. 5 2 2.5 3 3.5 4 4.5 40% 5 0% 60% 7 0% 80% 9 0% 100%
MP2012 ? 1.5a synchronous step-dow n converter MP2012 rev. 1. 01 www.monolithicpower.com 5 9/22/2011 mps proprietar y information. pate nt protec ted. un authorized photo c op y and d uplication prohibited. ? 2011 mps. all rights reserved. typical perfo r manc e characteristics v in = 5v, v out = 1.8v, l=3.3uh, t a = +25oc, unless otherwise noted. input ripple v oltage v in 50mv/div short entry full load en start up without load short recovery no load power up without load power up with 1.5a load sw 2v/div v out 2v/div v in 10v/div en 2v/div i induct or 2a/div sw 5v/div v out 1v/div v in 5v/div i induct or 1a/div sw 5v/div v out 1v/div i induct or 1a/div sw 5v/div v out 1v/div v in 10v/div i induct or 2a/div sw 5v/div v out 1v/div v in 5v/div i induct or 1a/div en start up with 1.5a load en 2v/div sw 5v/div v out 1v/div i induct or 1a/div sw 2v/div 400ns/div 400ns/div 400us/div output ripple v oltage sw 2v/div v out 20mv/div i induct or 2a/div load t ransient response i out =0.75a-1.5a step @ 1a/us v out 20mv/div i out 500ma/div
MP2012 ? 1.5a synchronous step-dow n converter MP2012 rev. 1. 01 www.monolithicpower.com 6 9/22/2011 mps proprietar y information. pate nt protec ted. un authorized photo c op y and d uplication prohibited. ? 2011 mps. all rights reserved. function block di agram figure 1 D function block diagram
MP2012 ? 1.5a synchronous step-dow n converter MP2012 rev. 1. 01 www.monolithicpower.com 7 9/22/2011 mps proprietar y information. pate nt protec ted. un authorized photo c op y and d uplication prohibited. ? 2011 mps. all rights reserved. operation the mp201 2 is a fixed f r equency 1.2mhz curre nt mode 1.5a step-down converter, optimized for low voltage, li-ion batt e ry powere d applicatio ns where high efficiency a nd small size are critica l . MP2012 integrates a high side pfet main swit ch and a low side synchr onous rectif ier. it always operates in continuo us conduction mode, simplifies th e control scheme and eliminates th e random spectrum noise due to discontinu o u s conduction mode. the steady state duty cycle d for this mode can be calculated as: % 100 v v % 100 f t d in out osc on = where t on is the main switch on time and f osc is the oscillato r frequency (1.2mhz typ . ). current mo de pwm co ntrol slope compensated cur r ent mode pwm control provides stable switch ing and cycle-by-cycle current limiting for superior loa d and lin e response a s well as protection o f the internal main switch and synchronous r e ctifier. th e MP2012 switches at a consta nt frequen cy (1.2mhz) and modulates the ind u ctor peak current to regulate the output voltage. specifically, for each cy cle the pw m controller forces the inductor pe ak current to an inter nal referen c e level derived from the feedback err o r voltage. at normal operation, the main switch is turned on a t each rise edge of th e internal oscillator, a nd remains on f o r a certain period of tim e to ramp up the inductor current. a s soon as the inductor current reaches the r eference le vel, the main switch is turned off and immediately t h e synchronous rectif ier will be turne d on to provid e the inductor current. in forced pw m mode, th e synchronous rectif ier will stay on until the ne xt oscil l ator cy cle. dropout op eration the mp201 2 allows the main switch to remain o n for more than one switching cycle t o increase t h e duty cycle when the i nput voltage is dropping close to the output voltage. when the duty cycle reaches 10 0%, the main switch is he ld o n continuously to deliver current to the output up to the pfet current limit. in this case, the outp u t voltage becomes the input voltage minus th e voltage drop across t he main switch and t he inductor. maximum load curren t the mp201 2 can oper ate down to 2.5v inp u t voltage; however the ma ximu m load current decreases a t lower input due to a l a rge ir dro p on the main switch a nd synchronous rectif ier. the slope compensation signal red u ces the pe ak inductor current as a fu nction of the duty cycle t o prevent sub-harmonic oscillations a t duty cycles greater than 50%. co nversely, th e current limit increases a s the duty cycle decrea s es. short circu i t protection when shor t circuit or over current condition happens, and fb is lower than ab out 0.3v, th e MP2012 enters fold ba ck mode. t he oscillato r frequency is reduced to prevent the inducto r current from increasing beyond the pfet current limit. the pfet current limit is also reduced to lower the short circuit cu rrent. the frequency and current limit will return to the normal values once the short circuit cond ition is removed and the feedback voltage approa ches 0.8v.
MP2012 ? 1.5a synchronous step-dow n converter MP2012 rev. 1. 01 www.monolithicpower.com 8 9/22/2011 mps proprietar y information. pate nt protec ted. un authorized photo c op y and d uplication prohibited. ? 2011 mps. all rights reserved. appli c ation information output voltage setting the external resistor divider sets the output voltage. 1 o u t 2 r v 0 . 8 1 r ?? = + ?? ?? rt is recommended wh en output voltage is h i gh , as the figur e 2 shows. r1 fb rt r2 v ou t figure 2 ? feedback netw ork table 1 lists the recommended resist or value for common out put voltages. table 1?resistor selection vs. output voltage setting v out / v rt / k
r1 / k
r2 / k
l1 / h c2 / f 1.2 300 4.99 10 2.2 22 1.8v 243 4.99 4.02 3.3 22 2.5v 100 121 57.6 3.3 22 3.3v 100 121 39 3.3 22 inductor selection a 1 h to 10 h inductor with dc current rating a t least 25% higher than the maxi mu m load current is recommended for most applications. for be st efficiency, t he inductor dc resistance shall b e <200m
. see table 2 for recommende d inductors a nd manufacturers. for most design s , the inducta nce value can be derived from th e following eq uation: () osc l in out in out f i v v v v l ? = where ? i l is inducto r ripple current. choose inductor rip p le current approximate l y 30% of th e maxi mum lo ad current, 1.5a. the maxi mu m inductor peak current is: 2 i i i l load ) max ( l + = table 2?suggested inductors manufac ture r p art numb er inducta nce ( h) dimensions lxwxh (m m 3 ) cooper sd25-3r3 3.3 5.2x5.2x2.5 toko d63 lcb#a 92 1 cy-3 r6m 3.6 6.3x6.2x3 tdk slf704 5t- 3r3m 2r5-pf 3.3 7x7x4.5 input capacitor c in selection the input capacitor red u ces the surge curren t drawn from the input and switching noise fro m the device. ceramic capacitors wit h x 5 r or x7r dielectrics are highly recommende d because of their low esr and small temperature coefficients. fo r most applications, a 10 f capacitor is suff icient. output cap acitor c out selection the output capacitor ke eps output voltage ripple small and ensures reg u lation loop stable. th e output capa citor impedance shall be low at t h e switching fr equency. ceramic capacitors with x 5 r or x 7 r dielectrics are reco mmended. for forced pwm mode op eration, the output ripple ? v out is approximately: ( ) o u t i n o u t o u t e s r i n o s c o s c o u t v v v 1 1 v r v f l 8 f c ?? ?? = + ? ?? ?? ? ?? for most application s , a 22 f capacitor is sufficien t. thermal dissipation power dissipation shall be considered when operates MP2012 at ma ximu m 1.5a out put current. if t he junct i on temperature rises above 150 c, MP2012 will b e shut d o wn by intern al thermal protection cir c uit r y. the junct i on -to-ambient thermal resistance of th e 6-pin qfn (3mm x 3 m m) r , ja is 50 c/w. th e maxi mum a llowable power dissipat ion is about 1.6w when MP2012 is operating in a 70 c ambient temperature environment: w 6 . 1 w / c 50 c 70 c 150 pd o o o max = ? =
MP2012 ? 1.5a synchronous step-dow n converter MP2012 rev. 1. 01 www.monolithicpower.com 9 9/22/2011 mps proprietar y information. pate nt protec ted. un authorized photo c op y and d uplication prohibited. ? 2011 mps. all rights reserved. pc board l a y out pcb la yout is very important to achieve stable operation. please follo w these g u idelines a n d take figure2 for references. the high cu rrent paths ( g nd, in and sw) should be placed very close to the device with short, direct and wide traces. input capa citors sh ould be placed as close as p o ssible to th e respective in and gnd pins. the external feedback resistors sh all be placed next to the fb pins. keep the switching no des sw sh ort and away from the feedback netw o rk. c1 l1 c2 c5 r4 r1 gnd r2 fb gnd pv i n sw vi n en 4 5 6 1 2 3 r3 r5 c3 c4 gn d vi n vou t gnd top la y e r bottom la yer figure 3?pcb la y out
MP2012 ? 1.5a synchronous step-dow n converter notice: t he i n formatio n in this docum ent i s subject to chang e w i t h o u t notice. users sh oul d w a rra nt and gu arante e that third part y int e ll ectu al prop ert y r i g h ts are n o t inf r ing ed u p o n w hen i n tegr atin g mps product s into an y ap p licatio n. mps w i ll not assume a n y le gal res pons ib ili t y for an y sai d app licati ons. MP2012 rev. 1. 01 www.monolithicpower.com 10 9/22/2011 mps proprietar y information. un a u thoriz ed photoc op y and duplication prohibited. ? 2011 mps. all rights reserved. package informati o n qfn6 (3mmx3mm) side view top view 1 6 4 3 bottom view 2.90 3.10 1.40 1.60 2.90 3.10 2. 20 2.40 0.95 bsc 0.35 0.45 0. 8 0 1.00 0.00 0.05 0.20 ref pi n 1 i d m arki ng 1.50 0.95 0.40 recommended land pattern 2.90 note: 1 ) al l di m e ns i o ns are i n m i l l i m e t e rs . 2 ) e x p o s e d p a ddl e s i z e do e s n o t i ncl ud e m o l d f l as h . 3 ) l e ad co p l a nari t y s hal l be 0 . 10 mil l i m e t e r m a x . 4 ) je d e c r e f e r e n c e i s m o - 229, v a r i a t i o n v e e a - 2 . 5 ) draw i n g i s no t t o s cal e . pi n 1 i d see detail a 2.30 0.80 pin 1 id option a r0.20 typ. p i n 1 i d op t i on b r0 . 2 0 t y p . detail a 0.35 0.55 pin 1 id index area
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