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MPQ8616 high efficiency , 6a/12a, 6v sy nchronous step-down converter MPQ8616 rev. 1 . 01 www.monolithicpower.com 1 2/4/2013 mps proprietar y information. pate nt protec ted. un authorized photo c op y and d uplication prohibited. ? 2013 mps. all rights reserved. the future of analog ic technology descri ption the mpq86 16 is fully integrated high frequency synchronous rectif ied step-down switch mode converter. it offers very compact solution s t o achieve 6a/12a output current from a 3v to 6v input with excellent loa d and line reg ulation. constant-on-time (cot) control mode provi des fast transient respo n se and eases loop stabilization. t h e m p q 8 6 1 6 can op erate with a low-cost e l e c trolytic cap acitor and can support ceramic output capacitor with external slop e compensation. operating frequency is programmed by an external resistor and is compensated for variations in v in . it is almost consta nt with all th e input voltage and output load condit i ons. under voltage lockout is internally set at 2.8 v, but can b e increa se d by prog ramming th e threshold with a resisto r network on the enable pin. the out put voltage startup ramp is con t rolled by the soft start pin. a power good sign al indicates th e output is within its no minal voltage range. full fault pr otection including ocp, scp, ovp uvp and otp is provided by internal comparators. the mpq8 616 req u ire s a min i mu m number of read ily ava i la ble stan da rd extern al compon ent s and a r e a v a i l a b l e i n qfn3x4 packages. features ? wide 3v to 6v operating input range ? 6a/12a out put current ? low r ds (on) internal power mosfets ? proprietary switching loss reduction technique ? adaptive cot for ultrafast transient response ? 1% reference voltage over -20 c to +8 5 c junction te mperature range ? programma ble soft start time ? pre-bias start up ? programma ble switching freque ncy from 300khz to 1 m hz. ? minimu m o n time t on_min =60ns minimu m of f time t off_mi n =100ns ? non-latch ocp, non-l a tch ovp protection and thermal shutdown ? output adjustable from 0.61v to 4.5v appli c ations ? telecom system base stations ? networking systems ? server ? personal video recorders ? flat panel t elevision an d monitors ? distributed power systems a l l m p s p a r t s a r e l e a d - f r e e a n d a d h e r e t o t h e r o h s d i r e c t i v e . for mp s gr een sta t u s , plea se v isit mps w ebsite under produ cts, quali t y assuran c e page. ?mp s ? and ?th e fu ture o f a nal og ic t e chno lo gy ? are re gi ster ed tr ad ema r ks o f monolithic pow e r sy st em s , inc. typical application in fr e q vc c en pgn d bs t fb sw m p q 8616 v in on / o f f c1 r fre q c5 c3 l1 r4 c4 r1 r2 c2 r3 pg ag n d ss v ou t c6 v cc http://
MPQ8616, 6a/12a, 6v, synchro nous step-down converter MPQ8616 rev. 1 . 01 www.monolithicpower.com 2 2/4/2013 mps proprietar y information. pate nt protec ted. un authorized photo c op y and d uplication prohibited. ? 2013 mps. all rights reserved. ordering information part number* package top marking mpq861 6gl - 6 qfn (3x4mm ) mp8616 6 mpq861 6gl - 12 qfn (3x4mm ) mp8616 12 * for tap e & reel, ad d suf f ix ?z (e.g. MPQ8616 gl -6 /12?z); package reference top view 1 2 3 4 5 6 78 9 10 11 12 13 14 sw sw f r e q in in ag nd fb ss en vc c pg bs t g nd g n d exposed pad on backside top view 1 2 3 4 5 6 789 10 11 12 13 14 sw sw fre q i n i n ag n d fb ss en vc c pg bs t g nd g n d exposed pad on backside part number** package part number** package MPQ8616gl-6 qfn14 ( 3x4mm ) MPQ8616gl-12 qfn14 ( 3x4mm ) ** for tape & reel, add suffix ?z (eg. MPQ8616gl-6?z) *** for tape & reel, add suffix ?z (eg. MPQ8616gl-12?z)
MPQ8616, 6a/12a, 6v, synchro nous step-down converter MPQ8616 rev. 1 . 01 www.monolithicpower.com 3 2/4/2013 mps proprietar y information. pate nt protec ted. un authorized photo c op y and d uplication prohibited. ? 2013 mps. all rights reserved. absolute m a xi mum ratings (1) supply voltage v in ...................................... 6.5v v sw ........................................ -0.3v to v in + 0.3v v sw (30ns) ................................... -3v to v in + 3v v in -v sw ................................. -0.3v to v in + 0.3v v in -v sw (3 0 n s) ............................ -3v to v in + 3v v bst ...................................................... v sw + 6v all other pins .................................. -0.3v to +6v continuous power dissipation (t a =+ 25 ) (2) ?? qfn(3 x 4mm)?? ?? ???...? ????2.6 w junction te mperature ............................... 150 c lead temperature .................................... 260 c storage temperature ............... -65 c to +150 c recommended operating conditions (3) supply voltage v in ................................ 3v to 6v output voltage v out ...................... 0.61v to 4.5v operating junction temp. (t j ). -40c to +125c thermal resistance (4) ja jc qfn (3 x4mm) ......................... 48 ...... 10 ... 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 tempe r ature 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 ma ximu m allow able cont inuous po w e r di ssipation at an y ambient tem peratur e is calculated b y p d (max)=(t j (max)- t a )/ ja . excee d ing the maximum allow able po wer dissipation w ill cause ex cessive die temperature, and the reg u l ator w ill go into thermal sh utdo w n . inte rnal thermal shutdo w n circuitr y protects the device from perma ne nt damage. 3) the device is not guarant eed to function outside of its operating conditions. 4) measured on jesd51-7, 4-layer pcb.
MPQ8616, 6a/12a, 6v, synchro nous step-down converter MPQ8616 rev. 1 . 01 www.monolithicpower.com 4 2/4/2013 mps proprietar y information. pate nt protec ted. un authorized photo c op y and d uplication prohibited. ? 2013 mps. all rights reserved. electri c al characteristi cs v in = 5v, t j = -40 to +125 c, unless otherw ise noted. parameters sy mbol conditio n min t y p max units supply current supply cu rre nt (shutdo wn ) i in v en = 0v 1 2 a supply cu rre nt (quie s cent ) i in v en = 2v, v fb = 1v 0.6 1.05 1.3 ma mosfet mpq861 6-6, t j =25 c 19.8 high -si de swi t ch on resi st ance hs rds-on mpq861 6-1 2 , t j =25 c 16 m ? mpq861 6-6 t j =25 c 15.3 low-si de swi t ch on resi st ance ls rds-on mpq861 6-1 2 , t j =25 c 8.4 m ? switch le aka ge sw lkg v en = 0v, v sw = 0v or 5v 0.01 3 a current limit mpq861 6-6 9.5 12 14.5 high -si de current limit i li m i t mpq861 6-12 17 23 27 a timer one-s hot on time t on r freq =165 k ? ,v out =1.2v 200 ns minimum off time t off 50 100 150 ns fold ba ck ti mer (5) t foldb a ck ocp hap pen s 2.5 s ov er-voltage and under-voltage protection ovp thres h old v ovp 110% 120% 130% v ovp delay (5) t ovp 1 s uvp thres hold (5) v uvp 50% v ref reference and soft start t j = -20 c to +85 c 604 610 616 referen c e vo ltage v ref t j = -40 c to + 125 c 601 610 619 mv feedb ack cu rre nt i fb v fb = 610mv 0.001 150 na soft start chargin g cu rren t i ss v ss =0v 5 7.5 10 a
MPQ8616, 6a/12a, 6v, synchro nous step-down converter MPQ8616 rev. 1 . 01 www.monolithicpower.com 5 2/4/2013 mps proprietar y information. pate nt protec ted. un authorized photo c op y and d uplication prohibited. ? 2013 mps. all rights reserved. electri c al characteristi cs (continued) v in = 5v, t j = -40 to +125 c, unless otherw ise noted. note : 5) guar anteed b y d e sign. parameters sy mbol conditio n min t y p max units enable and uvlo enable input low voltag e vil en 1.4 1.8 v enable hy ste r esi s v en-h y s 890 mv v en = 2v 1.5 2 enable input curre n t i en v en = 0v 0.01 1 a vcc uv lo vcc unde r voltage lo cko u t thre sh old ri sing vcc vth 2.3 2.8 2.95 v vcc unde r voltage lo cko u t thre sh old hy stere s i s vcc hy s 300 mv po w e r good powe r goo d risi ng th re shold pg vth-hi 84% 90% 96% v ref powe r goo d falling th re shold pg vth-lo 63% 70% 73% v ref powe r goo d deglit ch time r pg td t ss =1m s , 2000 5000 s powe r goo d sink cu rrent capability v pg sink 4ma 0.4 v powe r goo d lea kag e cu rrent i pg_l eak v pg = 3.3v 50 150 na thermal pro tection therm a l shut down t sd note 5 150 160 c therm a l shut down hyste r e s is 25 c
MPQ8616, 6a/12a, 6v, synchro nous step-down converter MPQ8616 rev. 1 . 01 www.monolithicpower.com 6 2/4/2013 mps proprietar y information. pate nt protec ted. un authorized photo c op y and d uplication prohibited. ? 2013 mps. all rights reserved. typical characteri s tics MPQ8616, performance waveforms are tested on the evaluation board of the design example section.
MPQ8616, 6a/12a, 6v, synchro nous step-down converter MPQ8616 rev. 1 . 01 www.monolithicpower.com 7 2/4/2013 mps proprietar y information. pate nt protec ted. un authorized photo c op y and d uplication prohibited. ? 2013 mps. all rights reserved. typical characteri s tics (conti nued) MPQ8616gl, performance waveforms are tested on the evaluation board of the design example section.
MPQ8616, 6a/12a, 6v, synchro nous step-down converter MPQ8616 rev. 1 . 01 www.monolithicpower.com 8 2/4/2013 mps proprietar y information. pate nt protec ted. un authorized photo c op y and d uplication prohibited. ? 2013 mps. all rights reserved. typical perfo r manc e characteristics performanc e w aveforms are tested on the evaluation board of the design example section. MPQ8616gl-6, v in =5v, v out =1.2v, l=1.0h, t a =+25c, unl ess otherw i se noted. 85 87 89 91 93 95 97 80 82 84 86 88 90 92 94 96 98 80 82 84 86 88 90 92 94 96 90 91 92 93 94 95 96 97 98 99 100 90 91 92 93 94 95 96 97 87 88 89 90 91 92 93 94 95 96 97 85 87 89 91 93 95 97 85 87 89 91 93 95 97 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 o ut put c ur r e nt ( a ) 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 o ut put c ur r e nt ( a ) 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 o u tp u t c u r r e n t (a ) 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 o ut put curr e nt ( a ) 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 o u tp u t c u r r e n t (a ) 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 o u tp u t c u r r e n t (a ) 85 87 89 91 93 95 97 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 o ut put curr e nt ( a ) 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 o u tp u t c u r r e n t (a ) 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 o ut put curr e nt ( a )
MPQ8616, 6a/12a, 6v, synchro nous step-down converter MPQ8616 rev. 1 . 01 www.monolithicpower.com 9 2/4/2013 mps proprietar y information. pate nt protec ted. un authorized photo c op y and d uplication prohibited. ? 2013 mps. all rights reserved. typical perfo r manc e characteristics (c ontinued) performanc e w aveforms are tested on the evaluation board of the design example section. MPQ8616gl-6, v in =5v, v out =1.2v, l=1.0h, t a =+25c, unl ess otherw i se noted. frequency (khz) frequency (khz) frequency (khz) line regulation load regulation frequency vs. input v oltage frequency vs. load current frequency vs. r freq supply current ( q uiescent) vs. vcc v oltage supply current ( shutdown) vs. t emperature one-shot-on t ime vs. v in output current (a) v in (v) i out (a) v in (v) vcc voltage (v) load current (a) input vol t age (v) 90 91 92 93 94 95 96 97 98 99 100 0.5 1 .5 2.5 3 .5 4.5 5 .5 6.5 -0.60 -0 . 4 0 -0 . 2 0 0. 00 0. 20 0. 40 0. 60 34 56 -0.6 -0 . 4 -0 . 2 0 0. 2 0. 4 0. 6 01 234 56 0 200 400 600 800 1000 1200 200 400 600 800 1000 1200 550 570 590 610 630 650 3 3 .5 4 4 .5 5 5 .5 6 550 560 570 580 590 600 610 0123456 300 400 500 600 700 800 900 3 3 .5 4 4 .5 5 5 .5 6 500 600 700 800 900 1000 1100 1200 3 3 .5 4 4 .5 5 5 .5 6 -1.0 -0 . 5 0. 0 0. 5 1. 0 3 3 .5 4 4 .5 5 5 .5 6 i out =0a i out =3a i out =6a
MPQ8616, 6a/12a, 6v, synchro nous step-down converter MPQ8616 rev. 1 . 01 www.monolithicpower.com 10 2/4/2013 mps proprietar y information. pate nt protec ted. un authorized photo c op y and d uplication prohibited. ? 2013 mps. all rights reserved. typical perfo r manc e characteristics (c ontinued) performanc e w aveforms are tested on the evaluation board of the design example section. MPQ8616gl-6, v in =5v, v out =1.2v, l=1.0h, t a =+25c, unl ess otherw i se noted. v sw 500mv/div. dead time (on) i out = 6a v sw 1v/div. dead time (off) i out = 6a v sw 5v/div. v out (ac) 10mv/div . v in (ac) 10mv/div . i l 2a/div . v sw 5v/div . v out (ac) 10mv/div . v in (ac) 10mv/div . i l 2a/div . v sw 5v/div . v out (ac) 10mv/div . v in (ac) 50mv/div . i l 5a/div . input/output voltage ripple i out = 0a input/output voltage ripple i out = 0.3a input/output voltage ripple i out = 6a v out 1v/div . v in 2v/div . v pg 2v/div. v out 1v/div . v in 2v/div . v pg 2v/div . v out 1v/div . v en 5v/div . v pg 5v/div . v out 1v/div . v en 5v/div . v pg 5v/div . power good through v in start-up i out = 6a power good through v in shutdown i out = 6a power good through en start-up i out = 6a power good through en shutdown i out = 6a
MPQ8616, 6a/12a, 6v, synchro nous step-down converter MPQ8616 rev. 1 . 01 www.monolithicpower.com 11 2/4/2013 mps proprietar y information. pate nt protec ted. un authorized photo c op y and d uplication prohibited. ? 2013 mps. all rights reserved. typical perfo r manc e characteristics (c ontinued) performanc e w aveforms are tested on the evaluation board of the design example section. MPQ8616gl-6, v in =5v, v out =1.2v, l=1.0h, t a =+25c, unl ess otherw i se noted. v out 1v/div . v in 5v/div . v sw 5v/div . i l 2a/div . v out 1v/div . v in 5v/div . v sw 5v/div . i l 5a/div. v sw 5v/div. v out 1v/div . v in 5v/div . i l 2a/div . v sw 5v/div . v out 1v/div . v in 5v/div . i l 5a/div . v sw 5v/div . v out 1v/div . v en 5v/div . i l 2a/div . v out 1v/div . v in 5v/div . v sw 5v/div . i l 5a/div. v out 1v/div . v in 5v/div . v sw 5v/div . i l 5a/div . v out 1v/div . v en 5v/div . v sw 5v/div . i l 5a/div . v out (ac) 50mv/div . i l 50ma/div .
MPQ8616, 6a/12a, 6v, synchro nous step-down converter MPQ8616 rev. 1 . 01 www.monolithicpower.com 12 2/4/2013 mps proprietar y information. pate nt protec ted. un authorized photo c op y and d uplication prohibited. ? 2013 mps. all rights reserved. typical perfo r manc e characteristics (c ontinued) performanc e w aveforms are tested on the evaluation board of the design example section. MPQ8616gl-6, v in =5v, v out =1.2v, l=1.0h, t a =+25c, unl ess otherw i se noted. v out 1v/div . v sw 5v/div . i l 5a/div . v out 1v/div . v sw 5v/div . i l 5a/div. v sw 5v/div. v out 1v/div . i l 5a/div .
MPQ8616, 6a/12a, 6v, synchro nous step-down converter MPQ8616 rev. 1 . 01 www.monolithicpower.com 13 2/4/2013 mps proprietar y information. pate nt protec ted. un authorized photo c op y and d uplication prohibited. ? 2013 mps. all rights reserved. typical perfo r manc e characteristics MPQ8616gl-12, v in =5v, v out =1.2 v, l=1.0h, t a =+25 c, unless otherw ise noted . output current (a) output current (a) output current (a) output current (a) output current (a) output current (a) output current (a) output current (a) output current (a) 83 85 87 89 91 93 95 97 0 1 2 3 4 5 6 7 8 9 10 1 1 12 13 85 87 89 91 93 95 97 1 02 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3 87 88 89 90 91 92 93 94 95 96 97 0 1 2 3 4 5 6 7 8 9 10 1 1 12 13 89 88 90 91 92 93 94 95 96 97 0 1 2 3 4 5 6 7 8 9 10 1 1 12 13 92 93 94 95 96 97 98 99 100 0123 456789 1 0 1 1 1 2 1 3 80 82 84 86 88 90 92 94 96 0123456 789 1 0 1 1 1 2 1 3 80 82 84 86 88 90 92 94 96 98 0123 456789 1 0 1 1 1 2 1 3 85 87 89 91 93 95 97 012 3456 789 1 0 1 1 1 2 1 3 85 87 89 91 93 95 97 0 1 2 3 4 5 6 7 8 9 10 1 1 12 13
MPQ8616, 6a/12a, 6v, synchro nous step-down converter MPQ8616 rev. 1 . 01 www.monolithicpower.com 14 2/4/2013 mps proprietar y information. pate nt protec ted. un authorized photo c op y and d uplication prohibited. ? 2013 mps. all rights reserved. typical perfo r manc e characteristics (c ontinued) MPQ8616gl-12, v in =5v, v out =1.2 v, l=1.0h, t a =+25 c, unless otherw ise noted . line regulation load regulation switching frequency vs. load current output current (a) input vol t age (v) input vol t age (v) load current (a) load current (a) 90 91 92 93 94 95 96 97 98 99 100 0 1 2 3 4 5 6 7 8 9 10 11 12 13 -0 . 8 -0 . 6 -0 . 4 -0 . 2 0. 0 0. 2 0. 4 0. 6 3 3 .5 4 4 .5 5 5 .5 6 -0 . 8 -0 . 6 -0 . 4 -0 . 2 0 0.2 0.4 0.6 02468 1 0 1 2 620 625 630 635 640 645 650 3 3 .5 4 4 .5 5 5 .5 6 560 570 580 590 600 610 620 630 640 650 02 468 1 0 1 2 i out =0a i out =6a i out =12a
MPQ8616, 6a/12a, 6v, synchro nous step-down converter MPQ8616 rev. 1 . 01 www.monolithicpower.com 15 2/4/2013 mps proprietar y information. pate nt protec ted. un authorized photo c op y and d uplication prohibited. ? 2013 mps. all rights reserved. typical perfo r manc e characteristics (c ontinued) MPQ8616gl-12, v in =5v, v out =1.2 v, l=1.0h, t a =+25 c, unless otherw ise noted .
MPQ8616, 6a/12a, 6v, synchro nous step-down converter MPQ8616 rev. 1 . 01 www.monolithicpower.com 16 2/4/2013 mps proprietar y information. pate nt protec ted. un authorized photo c op y and d uplication prohibited. ? 2013 mps. all rights reserved. typical perfo r manc e characteristics (c ontinued) MPQ8616gl-12, v in =5v, v out =1.2 v, l=1.0h, t a =+25 c, unless otherw ise noted .
MPQ8616, 6a/12a, 6v, synchro nous step-down converter MPQ8616 rev. 1 . 01 www.monolithicpower.com 17 2/4/2013 mps proprietar y information. pate nt protec ted. un authorized photo c op y and d uplication prohibited. ? 2013 mps. all rights reserved. typical perfo r manc e characteristics (c ontinued) MPQ8616gl-12, v in =5v, v out =1.2 v, l=1.0h, t a =+25 c, unless otherw ise noted .
MPQ8616, 6a/12a, 6v, synchro nous step-down converter MPQ8616 rev. 1 . 01 www.monolithicpower.com 18 2/4/2013 mps proprietar y information. pate nt protec ted. un authorized photo c op y and d uplication prohibited. ? 2013 mps. all rights reserved. pin functio n s MPQ8616gl-6, MPQ8616gl-12 pin # name description 1 agnd analog ground. 2 fb feedback. an external resistor divider from t he output to gnd, tapped to the fb pin, sets the output voltage. it is recommended to place t he resistor divider as close to fb pin as possible. vias should be avoided on the fb traces. 3 ss soft start. c onne ct on ex ternal capa cit o r to pro g ra m the soft start time for the switch mode regulator. 4 en enable pin. pull this pin highe r than 1.8v to enable the chip. for autom atic start - up , con n e c t en pin to vin with 100k ? re si st or. can be used to set the on/off threshold ( adjust uvlo) with two additional resistors. 5 vcc supply voltage for driver and control circuits. decouple with a minimum 4.7f ceramic capacitor as close to the pin as possible. x7r or x5r grade dielectric ceramic capacitors are recommended for their stable temperature characteristics. 6 pg powe r good output. it is high if the o u tput voltage is higher th an 90% of th e nominal voltage. there is a delay from fb 90% to pg goes high. 7 bst bootstra p. a cap a cito r con necte d bet we en sw a nd b s pins i s re q u ired to fo rm a floating supply across the high-side switch driver. 8-9 gnd system grou nd. this pin i s the refe ren c e grou nd of the reg u lated output voltag e. for this reason care must be taken in pcb layout. 10-1 1 in supply voltage. the in pin sup p lie s power for int e rnal mosf et and regu lator. the mpq861 6 op erate fro m a +3v to +6v in put rail. an in put cap a cito r is nee ded to decoupl e the input rail. use wid e pcb trace s and mu ltiple vias to make the conne ction. 12 freq freq uen cy se tting pin. a resistor connected between freq and in is required to set the switching frequency. the on time is determined by the input voltage and the resistor connected to the freq pin. in connect thr ough a resistor is used for line feed-forward and makes the frequency basically constant dur ing input voltage?s variation. an optional 1nf decoupling capacitor can be added to im prove any switching frequency jitter that may be present. 13-1 4 sw switch o u tpu t. conne ct this pin to the i n ducto r an d bo otstrap ca pa citor. this pi n i s drive n up to the vin voltage by the high -si de switch d u ri ng the on -time of the pwm du ty cycle. the ind u cto r curre n t drive s the sw pin n egativ e du rin g the off-time . the on -re si stan ce of the low-sid e swit ch an d the internal scho ttky diode fixes the nega tive voltage. use wi d e pcb traces t o make the conne ction.
MPQ8616, 6a/12a, 6v, synchro nous step-down converter MPQ8616 rev. 1 . 01 www.monolithicpower.com 19 2/4/2013 mps proprietar y information. pate nt protec ted. un authorized photo c op y and d uplication prohibited. ? 2013 mps. all rights reserved. block diagram 0. 61 v 0. 3 v 0. 7 5 v fr e q vc c en ss fb pg in bs t sw gn d agnd rs e n hs - f e t hs dr i v e r ls - f e t ls dr i v e r c u rre nt mo d u la t o r lo g i c c u rre n t s e ns e am p l i f e r re f r e s h ti m e r oc o v e r- c u rre n t ti m e r xs xr q pw m bs tr e g of f ti m e r il i m hs l i m i t c o m p ar ato r st a r t on ti m e r lo op co m p a r a t o r uv ov uv de t e c t co m p a r a t o r ov d e t e c t co m p a r a t o r p good co m p a r a t or so f t st a r t / s t o p re f e r e n c e 1m e g vc c figure 1?functional block diagram
MPQ8616, 6a/12a, 6v, synchro nous step-down converter MPQ8616 rev. 1 . 01 www.monolithicpower.com 20 2/4/2013 mps proprietar y information. pate nt protec ted. un authorized photo c op y and d uplication prohibited. ? 2013 mps. all rights reserved. operation pwm operation the MPQ8616 is fully integrated synchronous rectified step-down switch mode converter. constant-on-time (cot) control is employed to provide fast transient response and easy loop stabilization. at the beginning of each cycle, the high-side mosfet (hs-fet) is turned on when the feedback voltage (v fb ) is below the reference voltage (v ref ), which indicates insufficient output voltage. the on period is determined by the input voltage and the frequency-set resistor as follows: fre q on in 4. 8 r ( k ) t( n s ) v ( v ) 0. 49 = ? (1) after the on period elapses, the hs-fet is turned off, or becomes off state. it is turned on again when v fb drops below v ref . by repeating operation th is way, the converter r egulates th e output voltage. the inte grated low-side mosfet (ls-fet) is turned on w hen the hs-fet is in it s off state to minimize the conduction loss. the re will be a de ad short be tween input and gnd i f both hs-fet and ls-fet are turned on at th e same time. it?s calle d shoot-through. in order to avoid shoot-through, a dead-time (dt) is internally generated between hs-f et off and ls- fet on, or ls-fet off and hs-fet on. figure 2?pwm ope r ation MPQ8616 always op erating in continuou s- conduction- mode (ccm), which means the inductor cur r ent can go negative at light load. the ccm mode opera t ion is sho w n in figure2. when v fb is below v ref , hs-mosfet is turn ed on for a fixed interval which is de termined by one- shot on -timer as equation 1 sho w n. when the hs-mosfet is tur ned off, th e ls-mosf e t is turned on until next period. for the MPQ8616 is operated in ccm, t he switching fr equency is fairly constant and it is called pwm mode. sw itching frequenc y the selectio n of switching frequency is a trade off between efficiency an d component size. lo w frequency operation increases e fficiency b y reducing mosfet swit ching lo sses, but require s larger inductance and capacitan ce to maintai n low output voltage ripple . for mpq86 1 6 the on time can be set usin g freq pin, then the fre quency is set in steady state operation at ccm mode. adaptive constant-on-time (cot) control is u s ed in mpq861 6 and there is no dedicated oscillat or in the ic. connect freq pin to in pin t h roug h resistor r freq and th e input volt age is fee d- forwarded to the one-shot on-time timer through the resisto r r freq . when in steady state operation a t ccm, th e duty ratio is kept as v out /v in . he nce the swit ching frequ ency is fairly constant o v er the input voltage range. the switching fre quency can be set as follows: 6 sw fr e q in de lay in ou t 10 f( k h z ) 4.8 r (k ) v( v ) t( n s ) v ( v ) 0.49 v ( v ) = + ? (2) where t delay is the co mparator delay. it?s abo ut 40ns. generally, the mpq86 16 is set f o r 300khz t o 1mhz application. it is optimized to operate at high switch ing frequen cy with high efficien cy. high switch ing frequen cy makes it possib l e t o utilize small sized lc fi lter compon ents to save system pcb space. jitter and fb ramp sl ope figure 3 shows jitter occurring in pwm mode . when there is noise in the v fb downward slope, the on time of hs-fet deviates from its intended lo cation and produces jitter. it is necessary to understand that there is a relationship between a system?s sta b ility and th e steepness of the v fb ripple?s dow nward slope. the slope steepness of the v fb rip p le dominat es
MPQ8616, 6a/12a, 6v, synchro nous step-down converter MPQ8616 rev. 1 . 01 www.monolithicpower.com 21 2/4/2013 mps proprietar y information. pate nt protec ted. un authorized photo c op y and d uplication prohibited. ? 2013 mps. all rights reserved. in noise immunit y . the magnitude of the v fb ripple doe sn?t affe ct the noise immunity directly. figure 3?jitter in pwm mode ramp w i th large esr capacitor in the case of poscap or other types of capacitor wit h lager esr is applied a s output capacitor, th e esr ripple dominates the output ripple, and t he slope on the fb is quite esr related. figu re 4 shows an equivalent circuit in pwm mode with the hs-fet off and without an external ramp circuit. tur n to applicat ion information section for d esign step s with large esr capacitors. r1 r2 esr po sc ap sw vo l fb figure 4?simplified circuit in pwm mode w i thout ext e rnal ramp compensation to realize t he stability when no external ramp is applied, usu a lly the esr value should be chosen as follow: sw on esr out tt 0. 7 2 r c + (3) t sw is the switching period. ramp w i th small esr capacitor when the output capa citors are ceramic ones, the esr ripple is not high enough t o stabilize t he system, an d external ramp co mpensation is needed. skip to application information sectio n for design st eps with small esr caps. r1 r2 ce r a m i c sw fb vo l r4 c4 i r4 i c4 i fb r9 figure 5?simplified circuit in pwm mode w i th external ramp compensation in pwm mo de, an equivalent circu i t with hs-fet off and the use of an external ramp compensation circuit ( r 4, c4) is simplified in figure 5. t he external ramp is derived from th e inductor rip p le current. if one chooses c4, r9, r1 and r2 to meet the following con d ition: 12 9 sw 4 1 2 rr 11 r 2f c 2 0 r r ?? < + ?? + ?? (4) where: r 4 c4 f b c4 ii i i = + (5) and the ramp on the v fb can then be estimated as: in o 12 ra m p o n 44 12 9 vv r/ / r vt rc r / / r r ?? ? = ?? + ?? (6) the downward slope of the v fb ri p p l e t h en follows: ou t ra m p slop e 1 off 4 4 v v v tr c ? == (7) as can be seen from equation 7, if there is instability in pwm mod e , we can r educe eith e r r4 or c4. if c4 can not be reduced further due to limitation fr om equation 4, then we can only reduce r4. for a stable pwm o peration, th e v slope1 shou ld be design follow equation 8. sw on 3 esr ou t o sl op e 1 o u t out s w o n tt rc 0.7 i 10 0.7 2 vv 2l c t t ? +? ? + ? (8) where io is the load curr ent.
MPQ8616, 6a/12a, 6v, synchro nous step-down converter MPQ8616 rev. 1 . 01 www.monolithicpower.com 22 2/4/2013 mps proprietar y information. pate nt protec ted. un authorized photo c op y and d uplication prohibited. ? 2013 mps. all rights reserved. soft start/stop the mpq8 616 employs soft st art/stop (s s) mechanism to ensure smooth o u tput during power up and power down. when the en pin be comes high, an internal current source (8 a) charges up the ss capacitor c6. the ss capacitor voltage takes over the ref voltage to the pwm comparator. the outp u t voltage smoothly ramps up with the ss voltage . once the ss voltage reaches the same level a s the ref voltage, it keeps ramping up while v ref takes over the pwm comparator. at this point, the soft sta r t finishe s a nd it enters into steady state operation. when the en pin is pulled to low, the ss cap voltage is discharged through an 8ua internal current source. once the ss voltage reaches ref voltage, it takes over the pwm comparator. the output voltage will decrease smoothly with ss voltage until zero level. the ss capacitor value can be determined as follows: ss ss ss ref t( m s ) i ( a ) c( n f ) v = (9 ) if the out pu t capacitors have large capacitance value, it?s n o t recomme nded to set the ss time too small. otherwise, it?s easy to hit the curre nt limit during ss. a minimum value of 4.7nf should be used if the output capacitance value is larger than 330 f. pre-bias startup if the output is pre-bia s ed to a certain voltage during start up, the MPQ8616 will disabl e th e switching o f both high-side and low- side swit che s until the voltage on the inter nal soft-st art capacitor exceeds the sensed outp u t voltage a t the fb pin. pow e r good (pg) the mpq8 616 has po wer-good (pg) output. it can be con nected to v cc or other voltage source through a resistor (e.g. 100k). when the MPQ8616 is powered on and fb voltage reaches above 90% of ref voltage, the pg pin is pu lle d high. when the fb voltage drops to 70% of ref voltage or the part is n o t powered on, the pg pin will be pulle d low. over-cu rre nt protection (ocp) the mpq8 616 enters over-current protectio n mode when the induct o r current hit s the curren t limit, and tries to recover from o v e r-current fault with hiccup mode. th at means in over-current protection, the chip will disa ble o u tput power stage, discharge soft- start capa citor and the n automatically try to soft -start again. if the over- current con d ition still h o lds after soft-start end s, the chip re peats this operation cycle till ove r - current disappears and output rises back t o regulation level. the MPQ8616 also operates in hiccup mod e when short circuit hap pens. over/under ?voltage protection (ovp/uvp) the mpq8 616 has n on-latching over voltage protection. it monitors the output voltage through a resistor divider feedback (fb) voltage to detect over-voltage on the output. when the fb voltag e is higher than 120% of t he ref volt age (0.610v), the ls-fet will be turned on while the hs-fet will be off. the ls-fet keeps on u n til it hit s the negative current limit and turns off for 100ns. if over voltage condition st ill hold s , the chip repeat s this operati on cycle till the fb voltage drops below 110% of the ref voltage. when the fb voltage is below 50% of the ref voltage (0.610v), it is recognized as und er- voltage (uv). usually, uvp accompanies a hit in current limit and results in ocp. configurin g the en control the en pin provides electrica l on /off control of the device. set en high to turn on t he regulator and low to turn it off. do not float this pin. for automat ic start-up, t he en pin can be pulle d up to in put voltage thr ough a re sistive voltage divider. choose the values of the pull-up resist or (r up from vin pin to en pin) and the pull-dow n resistor (r dow n from en pin to gnd) t o determine the automatic start-up voltage: up down in st a r t dow n rr v1 . 4 r ? + = (10)
MPQ8616, 6a/12a, 6v, synchro nous step-down converter MPQ8616 rev. 1 . 01 www.monolithicpower.com 23 2/4/2013 mps proprietar y information. pate nt protec ted. un authorized photo c op y and d uplication prohibited. ? 2013 mps. all rights reserved. for exampl e, for r up =100k ? and r dow n =51k ? , the ? in st a r t v is set a t 4.15v. to avoid noise, a 10n f ceramic capacitor from en to gnd is recommen ded. there is a n internal ze ner diode o n the en pin, which clam ps the en pin voltage to prevent it from runnin g away. the ma ximu m pull up curren t assuming a worst case 6v internal zener clamp should be le ss than 1ma. therefore, when en is driven by an external logic signal, th e en voltage should be lo wer than 6v; when en i s connected with vin through a pu ll- up resistor or a resistiv e voltage divider, the resistance se le ction should ensure the maxi mum p u ll up curre nt less tha n 1ma. if using a resistive voltage divider and vin higher than 6v, the allowed minimum pull-up resistor r up should meet the following equation: in up d o w n v( v ) 6 6 1( m a ) r ( k) r ( k) ? ?< ? (11) as a result, when just the pull-up resistor r up is applied, th e ? in st a r t v is determined by i nput uvlo. the value of r up can be got as: in up v( v ) 6 r( k ) 1( m a ) ? > (12 ) a typical pull-up resistor is 100k ? . uvlo p r otection the MPQ8616 has under-voltage lock-out protection ( u vlo). wh en the vcc voltage is higher than the uvlo rising thre shold voltag e, the MPQ8616 will be powered up. it shut s o ff when the vcc voltage is lower tha n the uvlo falling thre shold volta ge. this is non-latch protection. the mpq86 16 is disabled when the vcc voltag e falls below its uvlo fal ling threshold (2.45v). if an application requires a higher under-voltage lockout (uv l o), use th e en pin a s shown in figure 6 to adjust the input volta ge uvlo b y using two e x ternal resistors. it is re commended to use the enable re sistors to set the uvlo falling threshold (v stop ) above 2.8 v. the risin g threshold ( v start ) should be set to provide enough hysteresis to allow for any input supply variations. en comparato r r up r down vcc en mpq 8616 in figure 6?adjustable uvlo thermal shutdow n thermal shutdown is e m ployed in the mpq861 6. the junctio n temperature of the i c is interna lly monitored. if the junction tempera t ure exceeds the thresh old value (minimum 150oc), the converter sh uts off. this is a non-latch protection . there is about 25oc hysteres is. once the junction te mperature drops to a bout 125oc, it initiates a so ft startup.
MPQ8616, 6a/12a, 6v, synchro nous step-down converter MPQ8616 rev. 1 . 01 www.monolithicpower.com 24 2/4/2013 mps proprietar y information. pate nt protec ted. un authorized photo c op y and d uplication prohibited. ? 2013 mps. all rights reserved. appli c ation information setting the output voltage-large esr caps for applications that ele c trolytic cap a citor or pos capacitor with a controlled output o f esr is set as output ca pacitors. th e output volt age is set by feedback re sistors r1 a nd r2. as figure 7 shows. r1 r2 esr po sc ap sw vo l fb figure7?si mplified circuit of pos capacitor first, choo se a value for r2. r2 should be chosen rea s onably, a small r2 will lead to considerable quiescent current lo ss while to o large r2 makes the fb noise sensitive. it is recommend ed to choo se a value within 5k ? - 100k ? for r2, using a comparatively larger r2 when v out is low, and a smaller r2 when v out is high. then r1 is determined as follow with the output ripple considered: out o ut r e f 12 ref 1 vv v 2 rr v ? ? = (13) ou t v is the outpu t ripple dete r mined by equation 21. setting the output voltage-small esr caps r1 r2 cer a m i c sw fb vo l r9 r4 c 4 figure8?si mplified circuit of ceramic capacitor when low esr ceramic capacitor is used in the output, an external voltage ramp should be added to fb through resistor r4 and capacit or c4.the output voltage is influen ced by ramp voltage v ramp besides r e sistor divid e r as shown in figure 8 . the v ramp can be calculated a s shown in equation 6. r2 should be chosen reasonably, a small r2 will lead to considerabl e quiescent current loss while too lar ge r2 makes the fb noise sensitive . it is recommended t o choose a value within 5k ? -100k ? for r2, using a comparative l y larger r2 when v out is low, and a smaller r2 when v out is high. and the value of r1 then is d e termined as follow: 2 1 fb( avg) 2 o u t f b ( avg ) 4 9 r r v r vv r r = ? ?+ (14) the v fb(avg ) is the average value on the f b . v fb(avg) varies with t he vin, vo, and load condition, et c.. it is mea ns the load regulation is strictly relat ed to the v fb(avg) . also the line regulation is related to the v fb(avg) ,if one wants to gets a b e tter load o r line reg u lation, a lower v ramp is sug gested once it meets equation 8. for pwm operation, v fb(avg) value can be deduced fro m equation 15. 12 f b(avg) ref ra m p 12 9 r/ / r 1 vv v 2r / / r r =+ + (15) usually, r9 is set to 0 ? , and it can also be set following equation 16 for a better no ise immunity. it should b e set to b e 5 timers smaller than r1//r2 to mi nimize its inf l uence on v r amp. 12 9 12 rr 1 r 10 r r ? + (16) using equat ion 14 and 15 to calcu l ate the outp u t voltage can be complicated. t o simplify the calculat ion of r1 in equation 14, a dc-blocking capacitor cdc can be added to filter the dc influence fr om r4 and r9. figur e 9 shows a simplified circuit with external ramp compensation and a d c -blocking capacitor. with this capacit or, r1 can easily be obtained by using equation 17 for pwm mode o peration. out r ef ra m p 12 ref r amp 1 vv v 2 rr 1 vv 2 ?? = + (17) cdc is sugg ested to be at least 10 times larger than c4 for better dc blocking performance, and should be not larger than 0.47 f considering startup performance. in case one wants to use larger cdc for a better fb noise immunity,
MPQ8616, 6a/12a, 6v, synchro nous step-down converter MPQ8616 rev. 1 . 01 www.monolithicpower.com 25 2/4/2013 mps proprietar y information. pate nt protec ted. un authorized photo c op y and d uplication prohibited. ? 2013 mps. all rights reserved. combined with reduced r1 and r2 to limit th e cdc in a re asonable va lue without affecting th e system start up. be noted that even when the cdc is applied, the load and line regulation are still vramp related. r1 r2 ce r a m i c sw fb vo l cdc r4 c 4 figure9?si mplified circuit of ceramic capacitor w i th dc blocking capacitor input capacitor the input current to the step-down converter is discontinu o u s. therefor e, a capacit or is require d to supply t he ac current to the step-down converter while maintaining the dc input voltage. ceramic ca pacitors are recommen ded for best performance. in the layout, it?s recommended to put the inpu t capacitor s as close to t he in pin as possible. the capa citance va ries significantly over temperature. capacitors with x 5 r and x 7 r ceramic die l ectrics are recommen ded because they are fairly stable over temperature. the capacit ors must also have a ripple current rating great er than the maxi mum input ripple current of th e converter. the input r i pple curren t can be estimated as follows: out o ut ci n o u t in in vv ii ( 1 ) vv = ? (18) the worst-case conditio n occurs at v in = 2v out , where: out ci n i i 2 = (19) for simplification, cho o se the in put capacit or whose rms current rating is greate r than half of the maxi mu m load current. the input ca pacitance value determines the inpu t voltage ripple of the co nverter. if there is inp u t voltage ripple requirement in the sy stem design , choose the input cap a citor that meets th e specification the input voltage ripp le can be estimated a s follows: out o u t out in s w in in in iv v v( 1 ) fc v v = ? (20) the worst-case condit i o n occurs at vin = 2vout , where: out in sw in i 1 v 4f c = ( 21) output cap acitor the output capacitor is required to maintain the dc output voltage. ceramic or poscap capacitors a r e recomme nded. the output voltage ripple can b e estimated as: ou t ou t out e s r sw i n s w o u t vv 1 v( 1 ) ( r ) fl v 8 f c = ? + (22) in the case of ceramic capacitors, th e impedance at the switching frequency is dominated by th e capacitan ce . the outpu t voltage ripple is mainly caused by the capacit ance. for simplificat io n, the output voltage ripple can be estimated as: ou t o ut out 2 in sw o u t vv v( 1 ) v 8f l c = ? (23) the output voltage ripple caused by esr is very small. therefore, an external ramp is needed t o stabilize the system. the external ramp can be generated through resistor r4 and capacitor c4 following eq uation 4, 7 a nd 8. in the case of poscap capacitor s, the esr dominates the impedance at the switching frequency. the ramp voltage gene rated from the esr is hig h enough t o stabilize the system. therefore, an external ramp is n o t needed. a minimu m esr value a ccording to equation 3 is required to ensure st able opera t ion of the converter. for simplification, the output ripple can be appr oximated as: ou t ou t ou t e s r sw i n vv v( 1 ) r fl v = ? (24) inductor the induct o r is re quired to sup p ly constan t current to t he output lo ad while be ing driven by the switch ing input voltage. a larger valu e inductor will result in le ss ripple curr ent and lower output ripple voltage. however, a larger valu e
MPQ8616, 6a/12a, 6v, synchro nous step-down converter MPQ8616 rev. 1 . 01 www.monolithicpower.com 26 2/4/2013 mps proprietar y information. pate nt protec ted. un authorized photo c op y and d uplication prohibited. ? 2013 mps. all rights reserved. inductor will have a larger physical size, higher series resistance, and/or lower saturation current. a good rule for determining the inductor value is to allow the peak-to-peak ripple current in the inductor to be approximately 10~30% of the maximum output current. also, make sure that the peak inductor current is below the current limit of the device. the inductance value can be calculated as: out o ut sw l in vv l( 1 ) fi v = ? (25 ) where i l is the peak-to-peak inductor ripple current. choose an inductor tha t will not sa turate under the maxi mu m inductor peak curren t. the peak inductor curr ent can be calculated a s : ou t ou t lp o u t sw i n vv ii ( 1 ) 2f l v =+ ? (26) the induct o rs listed in table 1 are highl y recommend ed for the high efficie n cy they can provide. table 1?inductor selection guide part numb er manufac ture r inducta nce (h ) dc r (m ? ) curre nt ratin g (a ) dimensions l x w x h (m m 3 ) s w i t ching freque nc y (kh z ) fdu125 0c-r50m toko 0.50 1.3 46.3 13.3 x 12.1 x5 1000 fdu125 0c-r56m toko 0.56 1. 6 42.6 13.3 x 12.1 x5 800-100 0 fdu125 0c-r75m toko 0.75 1. 7 32.7 13.3 x 12.1 x5 600-800 fdu125 0c-1 r0m toko 1.0 2.2 31.3 13.3 x 12.1 x5 600 t y pical des i gn parameter tables the following tables include r e commende d component values for typical ou tput voltages (1.0v, 1.2v, 1.8v, 3.3v) and switching frequencies (600khz, 80 0khz, and 1 m hz). refe r to tables 2 - 4 for desig n cases wit hout external ramp comp ensation an d tables 5- 6 for desig n cases wit h external ramp compensation. external ra mp is not needed when high-esr capacitors, such a s ele c trolytic or poscaps are used. external ramp is needed when low-esr capacitors, such as cer amic capacitors are use d. for cases n o t listed in t h is datashe et, a calcula t or in excel spreadsheet can also be requested through a lo cal sale s re presentative to assist wit h the calcu l ation. table 2?c out -poscap, 600khz, 5v in v out (v) l ( h) r1 (k ? ) r2 (k ? ) r7 (k ? ) 1.0 1.0 19.8 30 300 1.2 1.0 29.4 30 365 1.5 1.0 29.4 20 453 1.8 1.0 39.2 20 549 3.3 1.0 44.2 10 1000 table 3?c out -poscap, 800khz, 5vin v out (v) l ( h) r1 (k ? ) r2 (k ? ) r7 (k ? ) 1.0 0.75 20 30 210 1.2 0.75 20 20 270 1.5 0.75 30 20 330 1.8 0.75 39 20 499 3.3 0.75 44.2 10 750 table 5?c out -cerami c , 600khz, 5vin v out (v) l ( h) r1 (k ? ) r2 (k ? ) r4 (k ? ) c4 (pf) r7 (k ? ) 1.0 1 .0 21 30 240 470 309 1.2 1 .0 33 30 220 470 365 1.5 1 .0 51 30 330 390 464 1.8 1 .0 45 20 270 470 549 3.3 1 .0 62 10 160 680 953 table 6?c out -cerami c , 800khz, 5vin v out (v) l ( h) r1 (k ? ) r2 (k ? ) r4 (k ? ) c4 (pf) r7 (k ? ) 1.0 0 .75 21 30 200 470 226 1.2 0 .75 34 30 200 470 270 1.5 0 .75 34 20 220 470 324 1.8 0 .75 47.5 20 225 470 402 3.3 0 .75 57.6 10 200 560 750
MPQ8616, 6a/12a, 6v, synchro nous step-down converter MPQ8616 rev. 1 . 01 www.monolithicpower.com 27 2/4/2013 mps proprietar y information. pate nt protec ted. un authorized photo c op y and d uplication prohibited. ? 2013 mps. all rights reserved. typical application in fr e q vc c en pg n d bs t fb sw MPQ8616 vin c1 a r7 c5 c3 l1 r1 r2 r5 pg agnd ss c6 33nf 22uf c1 b 22u f c1 c 2 2uf c1 d 0. 1u f c1 e 22 uf c7 1n f 360k 10 r8 r6 100k 4.7uf 100k r3 0 1uh 29 . 4 k 30k vo u t c2a c2 b 0.1uf 1u f 220uf/20m + figure 13 ? t y pical application circuit w i t h no external ramp MPQ8616, v in =5v, v out =1.2v, i out =6/12a, f sw =600khz in fr e q vc c en pg n d bs t fb sw MPQ8616 vin c1 a r7 c5 c3 l1 r4 c4 r1 r2 r5 pg agnd ss c6 33nf 22uf c1b 2 2uf c1 c 22 u f c1 d 0.1 u f c1e 22 uf c7 1n f 360k 10 r8 r6 100k 4.7uf 100k r3 0 1u h 220k 470pf 33 k 30 k r9 0 vout c2a 22u f c2 b 22 uf c3 c 22 uf c2 d 0. 1uf 22uf c2e 1u f figure 14 ? t y pical application circuit w i t h lo w esr ceramic ca pacitor MPQ8616, v in =5v, v out =1.2v, i out =6/12a, f sw =600khz in fr e q vc c en pg n d bs t fb sw MPQ8616 vin c1 a r7 c5 c3 l1 r4 c4 r1 r2 r5 pg agnd ss c6 33nf 22uf c1b 2 2uf c1 c 22 u f c1 d 0.1 u f c1e 22 uf c7 1n f 360k 10 r8 r6 100k 4.7uf 100k r3 0 1u h 200k 560pf 29 . 1k 30 k cdc 1 0nf vout c2 a 22u f c2 b 22 uf c3 c 22 uf c2 d 0. 1uf 22u f c2 e 1u f figure 15 ? typical application circuit with low esr ceramic capacitor and dc-blocking capacitor . MPQ8616, v in =5v, v out =1.2v, i out =6/12a, f sw =600khz
MPQ8616, 6a/12a, 6v, synchro nous step-down converter MPQ8616 rev. 1 . 01 www.monolithicpower.com 28 2/4/2013 mps proprietar y information. pate nt protec ted. un authorized photo c op y and d uplication prohibited. ? 2013 mps. all rights reserved. layout recommendation 1. the high current paths (gnd, in, and sw) should be placed very close to t he device with short, d i rect and wide traces. 2. put the input capacitor s as close to the i n and gnd pi ns as possib l e. 3. put the decoupling cap a citor as close to the vcc and gnd pins as possible. 4. keep the switching no de sw short and away from the feedback netw o rk. 5. the external feedback resistor s should be placed next to the fb pin. make sure that there is no via on the fb trace. 6. keep the b s t voltage path (bst, c3, and sw) as shor t as possible . 7. keep the in and gnd pads conn ected with large copp er to achieve better thermal performance. 8. four-layer layout is stro ngly recommended to achieve better thermal performance. in fr e q vcc en pg n d bst fb sw mp q 8 6 1 6 v in c1 r fre q c5 c3 l1 r4 c4 r1 r2 c2 r3 pg agnd ss v ou t c6 r6 r5 schematic for pcb la y out guide line freq in r3 c1b r3 c1a r3 r1 r3 r2 r3 r3 r3 r4 r3 c4 r3 c6 r3 c5 l1 r3 c2 1 sw sw fr e q in ag nd fb ss en vc c pg bs t in g n d gn d vin gnd sw vo ut top la y e r gn d inner1 la y e r gnd inner2 la y e r r3 c3 r3 r5 r3 r6 r3 r freq vi n gnd vo ut bottom la yer figure 16?pcb la y o u t
MPQ8616, 6a/12a, 6v, synchro nous step-down converter notice: t he i n formatio n in this docum ent is subject to chang e w i t h o u t notice. please c ontact m ps for current specifi c ations. users sho u ld w a rrant a nd g u a rante e that thi r d part y inte lle ctual prop ert y rights ar e n o t infring ed u pon w h e n inte grati ng mps prod ucts into a n y app licati on. mps w i ll n o t assume an y l e g a l resp onsi b il ity for an y sa id a pplic atio ns. MPQ8616 rev. 1 . 01 www.monolithicpower.com 29 2/4/2013 mps proprietar y information. pate nt protec ted. un authorized photo c op y and d uplication prohibited. ? 2013 mps. all rights reserved. package informati o n side view bottom view note: 1 ) a l l d i m e n s ion s a r e in m i l l i m e t e r s . 2 ) ex p o sed p a d d l e s i z e d o es n o t i n cl u d e m o ld f l as h . 3 ) l e a d co plan ari ty s h a l l be 0. 10 m i lli m e te r s m a x . 4 ) j e d e c refe renc e i s m o - 2 2 0 . 5 ) dr a w i n g i s no t to s cal e . pi n 1 id ma r k in g top view pin 1 i d i n de x are a recommended land pattern 0.1x45

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