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AIC1896 1.4mhz sot23 current-mode s t ep-up dc/dc converter a n alog integrations corporation si-sof t research center ds-1896p-04 010405 3a1, no.1, li-hsin rd. i, science park, hsinchu 300, t a iw an, r.o.c. tel: 886-3-5772500 f ax: 886-3- 5772 510 www .analog.com .tw 1 features fixed frequ ency 1.4 m hz current -m ode p w m operation. adjust able output v o lt age up to 30v . guaranteed 13v/ 200ma output with 5v input. 2.5v to 10v input range. maximum 0.1a shut down current. programmable sof t -s t a rt. t i ny inductor and cap a citors are allowed. s p ace-saving sot - 23-6 package. applications white led backlight. oled driver . description aic189 6 is a cu rre nt-m od e pul se -wi d th modul ation (pwm ), step- up dc/ dc converte r . the built-in high volt age n-ch annel m o sf et allows a i c189 6 for step -up appli c ation s with up to 3 0 v ou tput volt age , as well a s f o r singl e en ded pri m ary induct a n c e conve r ter (s epic) and other lo w-si d e switchi n g dc/dc conv erter . the hig h swi t ching frequ e n cy (1.4 mhz) allows th e use of small external co mpon ent s. the sof t -s t a rt function i s programma ble with an external ca p a cito r , which set s the input current ramp rate. the aic189 6 is available in a sp a c e - savin g sot - 23-6 p a ckage. typical application circuit l x fb gnd ss shdn in a i c 1 896 l d1 c h 521s -30 c2 0.033 f r1 62 c1 4. 7 f on of f c3 1 f i le d v in zd 1 1 1 . 8 v ~ 12. 2v b z v 55- b 12 r2 1k ? 3.3v or 4.2v 6 4 1 3 5 2 68 70 72 74 76 78 80 82 84 86 2 4 6 8 10 12 14 16 18 20 le d current ( m a ) ef fi ci e n c y ( % ) l: gt s k -51-100m (10 h) l: gt s k -51-150m (15 h) v in =3. 3 v v in =4. 2 v fig. 1 li-ion powered driver for three white leds
AIC1896 l x fb gn d ss shdn in a i c 1 8 96 l d1 ch 521s -30 c2 0.03 3 f c1 4.7 f on of f c3 1 f v in 2 3 .5 v~ 2 4 .5 v bz v55 - b24 r2 1k ? 3.6v or 4.2v i le d zd 1 r1 62 6 4 1 3 5 2 le d current ( m a ) ef fi ci e n c y ( % ) 60 62 64 66 68 70 72 74 76 78 80 2 4 6 8 10 12 14 16 18 20 v in =3. 6 v v in =4. 2 v l: gt s k - 51-100m (10 h) l: gt s k - 51-150m (15 h) fig. 2 li-ion powered driver for six white leds ordering information packing t y pe t r : t ape & reel bg : bag packag e t y pe g : so t - 23- 6 c: commercial p: lead f r ee co mmercial a i c 1896- xxxx ex am ple: AIC1896- cg t r in so t - 23- 6 pac k age & t ape & reel pac k ing t y pe AIC1896- pg t r in lead f r ee so t - 23- 6 pac k age & t ape & reel pac k ing t y pe pin configurat i on 3 2 1 4 6 5 so t - 23- 6 f r o n t view 1: lx 2: gnd 3: f b 4: shdn 5: ss 6: in sot-23-6 marking part no. marking a i c 1 8 9 6 c g 1 8 9 6 a i c 1 8 9 6 p g 1 8 9 6 p 2
AIC1896 absolute maximum ratings lx to gnd -0.3v to + 33v fb to gnd -0.3v to + 6 v in, shdn -0.3v to + 1 1v ss to gnd -0.3v to + 6 v lx pin rms cu rre nt 0.6a continuous power dissip a tion (t a = +70c) 6-pin sot2 3 (de r ate 9.1m w/c a bove +70 c) 727mw ope r ating t e mperature ra nge -40c to 85c jun c tion t e m perature 125c s t orage t e m perature ran g e -65c to 150c lead t e m perature (sol de ri ng, 10s) 260c absolute maximum ratings are those v a lues bey ond w h ich the life of a dev i ce may be impaired. test circuit l x fb gnd ss s hdn in u1 a i c 1896 l1 d1 ss1 4 c2 0. 033 f r1 r2 62 + c4 10 f + c1 10 f/ 16v c5 1 f c3 s hdn v in 2. 5v t o 10v v out 6 4 1 3 5 2 gt s k - 51-100m (10uh ) 3
AIC1896 electrical characteristics (v in =v shdn =3v , fb=gnd, ss=open, t a =25 c, unless otherw i se specified) (note 1) p arameter symbo l conditions min t y p m a x units input supply range v in 2 . 5 1 0 v output v o lt age adjust range v out 3 0 v v in undervolt age lockout uvlo v in rising, 50mv hysteresis 2.2 v v fb = 1.3v , not switching 0.1 0.2 quiescent current i in v fb = 1.0v , switching 1 5 ma v shdn = 0, t a = +25 c 0 . 0 1 0 . 5 a shut down supply current v shdn = 0 0.01 10 a error amplifier feedback regulation set point v fb 1.205 1 . 2 3 1 . 2 5 5 v fb input bias current i fb v fb = 1.24v 21 80 na line regulation 2.6v < v in < 5.5v 0.05 0.20 %/v oscilla t o r frequency f os c 1000 1 4 0 0 1 8 0 0 khz maximum duty cycle dc 82 86 % power switch s t eady s t ate output current io refer to fig. 18 a on-resist ance r ds(on) v i n = 5v 1 1.4 ? v lx = 30v , t a = +25 c 0.1 1 leakage current i lx(off) v lx = 30v 10 a soft -st art reset switch resist ance guaranteed by design 100 ? charge current v ss = 1.2v 1.5 4 7.0 a control input input low v o lt age v il v shdn , v in = 2.5v to 10v 0.3 v input high v o lt age v ih v shdn , v in = 2.5v to 10v 1.0 v v shdn = 1.8v 25 5 0 shdn input current i shdn v shdn = 0 0.01 0.1 a note 1: s p eci f ication s a r e pro d u c tion te sted at t a =2 5 c. s p ecifi c ations over th e -4 0 c to 85 c op er a t ing temperature range are assure d by de sig n , cha r a c teri zation an d correlatio n with s t atistical qu ality controls (sqc). 4
AIC1896 typical performance characteristics -40 -20 0 20 40 60 80 100 1.20 1.25 1.30 1.35 1.40 1.45 1.50 f i g. 3 s w it c h ing freq uenc y v s . t e m perat ure v in =3. 6 v swi t c h ing freq uen c y (m hz ) t e m perat ure ( q c) 2 3 4 5 6 7 8 9 10 11 1. 30 1. 35 1. 40 1. 45 1. 50 f i g. 4 freq uenc y vs . s upp l y v o l t age t a =25 q c freq uenc y (mhz ) s upp l y v o lt age (v ) 2 3 4 5 6 7 8 9 10 11 0. 8 0. 9 1. 0 1. 1 1. 2 1. 3 1. 4 1. 5 1. 6 1. 7 s uppl y v o l t age (v ) fig . 5 r dso n vs . s u pply v o l t age r ds (on) ( : ) 1 10 10 0 4. 50 4. 75 5. 00 5. 25 5. 50 v in =3. 6 v o u tp u t c u r r e n t ( m a) fi g . 6 lo ad reg u lat i on ( l1= 10 h ) o u t put v o l t a ge ( v ) ou tp ut c u r r e n t ( m a) f i g. 7 load regul at i o n (l1=22 h) o u t p ut v o l t ag e ( v ) 1 10 10.5 11 . 0 11 . 5 12.0 12.5 v in =3. 6 v 100 2 3 4 5 6 7 8 9 10 11 0. 6 0. 8 1. 0 1. 2 1. 4 1. 6 1. 8 2. 0 2. 2 2. 4 fb= 1 .0 v sh d n =1 .0 v sup p ly v o lt a g e (v) fig. 8 s w it c h i n g cu r r e nt s u p p l y curren t (m a ) 5
AIC1896 typical performance characteristics (continued) 2 3 4 5 6 7 8 9 10 11 65 70 75 80 85 90 fb=1.3v shd n =1.0v s u p p ly v o lt a ge (v) fig. 9 non- s w it c h ing cur r ent supply c u rrent ( ? a) 0 100 20 0 300 40 0 50 0 60 0 60 65 70 75 80 85 90 out put current (m a ) fi g. 10 eff i c i enc y vs . out put current (l1=10 h , t e st ci r c u i t r e fe r t o p . 3 ) ef fi ci e n c y (% ) v ou t =5 .0 v l1: g t s k - 51 - 1 0 0 m v in =4. 2 v v in =3. 3 v v in =2 .5 v v in =3. 6 v v in =2. 7 v out put current (m a ) f i g. 1 1 eff i c i enc y vs . out p u t c u rr en t (l1=22 h , t e st ci r c u i t r e fe r t o p . 3 ) ef fi ci e n cy ( % ) 0 50 10 0 15 0 200 60 65 70 75 80 85 90 v in =3. 3 v v in =5. 0 v v in =3. 6 v v in =4 .2 v v out =3. 3 v l1: slf 6025-220mr fi g. 12 o per at ion w a ve f orm (v in =3 v ; v ou t =5v ; l1=10 h; r1=36k; r 2=12k ; c3= 39pf; i ou t =200 m a , t e s t c i rc uit ref er t o p. 3) v out v lx i lx 6
AIC1896 typical performance characteristics (continued) fig. 13 o per a t ion w a v e fo rm (v in =5 v ; v out =1 2v , l1 =22 p h ; r 1 =10 5k; r 2=1 2k ;c3 =1n f; i out = 2 0 0 m a, te st ci r c u i t r e f e r to p . 3 ) v out v sw i lx f i g. 14 s tart - up f r om s hutdo w n (v in = 3.3v ; v ou t = 13v ; r lo ad = 300 : , t e s t c i r c uit r efer t o p . 3 ) v ou t sh d n i lx fi g . 15 load s t ep res p o n s e (v in = 3 .3 v ; v out =5v ; l1=10 p h ;i ou t =5 m a t o 200m a , te s t cir c u i t r e fe r to p . 3 ) v ou t i lx fi g. 16 load s t e p res pons e (v in =5 v ; v ou t =12v ; l1=22 p h; i ou t =5m a t o 150m a , test cir c u i t r e fe r to p . 3 ) v ou t i lx 7
AIC1896 typical performance characteristics (continued) fig. 17 feedbac k p i n v o l t a g e feedba c k v o l t a g e (v ) t e m p e r at ur e ( c) -5 0 -2 5 0 25 50 75 100 1.20 1.21 1.22 1.23 1.24 1.25 v in =3 . 6 v fi g. 18 (a) m a x i m u m o u t put c u rrent vs . s upply v o lt age (l1 : 10 h , te s t cir c u i t r e fe r to p . 3 ) ma ximu m o u tp u t c u r r e n t ( m a) sup p l y v o l t ag e ( v ) 2 3 4 5 6 7 8 9 10 100 200 300 400 500 600 700 800 v out =1 5v v out =1 3v v ou t =9v v out =5v m a x i m u m out pu t c u rre nt def i n ed a t 90 % of n o l o ad out pu t v o l t a g e 50 100 150 200 250 300 350 3 4 5 6 7 8 9 10 11 0 m a x i mu m o u t p u t c u r r e n t d e f i n ed at 90% of n o l o ad ou tp ut vo l t ag e f i g. 18(b) m a x i m u m out put curren t vs . s upply v o l t a ge (l1: 22 h , te st c i r c u i t r e fe r to p . 3 ) ma ximu m o u tp u t c u rr e n t (m a) s u p p l y v o lt age (v ) v out =3 . 0 v v ou t =2.0v v out =2.5v 8
AIC1896 block diagram i9 cc q2 8 q1 1 rc r1 r2 r3 r4 rs x2 0 x1 4 a d ri ver s hdn ss l x so f t st a r t cont rol pw m / pf m vin + - pw m com parat o r c ontrol lo g ic 1. 4m hz os c illa to r fb e rror a m p + - gnd s l ope c o m pen sati on cu r r e n t am p x 5 - + pin descriptions pin 1: lx - powe r swit chin g conn ection. con n e c t lx to inductor and output re ct ifier . keep the dist a n ce betwee n the com pon ent s as cl ose to lx as possible. pin 2: gnd - ground. pin 3: fb - feed ba ck i nput. con n e ct a re sistive volt a ge-divider fro m the output to fb to set the output volt age. pin 4: shdn - shut do wn in put. drive shdn low to turn of f the c onverter . t o automati c ally st art the co n v erter , c o nn ec t shdn to in. driv e shdn with a s l ew rate of 0.1v/s or g r eater . do not leave shdn unconn ecte d . shdn draws up to 50a. pin 5: ss - sof t -s t a rt input. conn ect a sof t - s t a rt ca p a cit o r f r om s s t o gnd in ord e r to sof t -st a rt the conve r te r . leave ss open to disable the sof t -st a rt function. pin 6: in - internal bia s v o lt a ge input. con n e c t in to the input volt age s o urc e . byp a s s in to gnd with a c a p a c i tor s i tting as c l os e to in as possible. 9
AIC1896 application information inductor selection a 15 h in ducto r is re comm end ed for most aic189 6 ap plicatio ns. al though sm all size a n d high efficie n cy are majo r con c e r n s , the indu cto r sho u ld have low core lo sses at 1.4mhz and lo w dcr (copper wire resistance). 10 capacitor selection the small si z e of ceramic cap a cit o r s make s t hem ideal for ai c18 96 a ppli c ation s . x5r and x7 r types a r e recommen ded b e ca use they retain thei r cap a cita nce over wid e r range s of voltage an d temperature than othe r ty pes, su ch as y5v or z5u. a 4.7 f input cap a c itor a nd a 1 f output cap a cit o r ar e suf f i cie n t f o r most a i c189 6 applications. diode selection schottky dio des, with their low forward voltage dro p and fast reverse recove ry, are the ideal choi ce s for aic189 6 ap plicatio ns. t he forward voltage drop of a schottky diode rep r e s ent s the con d u c tion lo sses in the diode, whil e the diode cap a cit a nc e ( c t or c d ) rep r es en ts th e s w itc h ing losse s . for d i ode sele ctio n, both forwa r d voltage dro p and diode ca pa citan c e n e e d to be con s id ered. schottky di o des with hi g her cu rre nt rating s u s u a ll y have lo wer forward voltage d r o p and la rg er di ode cap a cita nce, whi c h can cau s e signifi cant switchi ng lo sse s at the 1.4mhz swit chin g fre quen cy of ai c18 96. a schottky dio d e rated at 1 0 0 m a to 200m a is suffici en t for most AIC1896 applications. led current control led cu rrent is co ntrolle d b y feedback re sisto r (r1 in fig. 1). th e feedb ack refere nce is 1 . 23v. the led current is 1.23v/r1. in orde r to have accu rate le d current, pre c i s ion re sisto r s are prefe r red (1 % recomme n ded ). the formula for r1 selection are shown below. r1 = 1.23v/i led ( 1 ) open-circuit protection in the cases of output o p e n ci rcuit, whe n the le ds are di scon ne cted from the circuit or the leds fail, the feedba ck voltage will be zero. aic18 96 will then switch t o a high duty cycle re sultin g in a high output voltage, which may cause sw pin voltage to exceed its maximum 30 v rating. a zene r diode can be u s ed at the output to limit the voltage o n sw pin (fig. 20). the ze ner voltag e sho u ld be larg er tha n t he maximu m forward voltage of th e led st ring. t he current rating of the ze ner sho u ld be larger than 0.1ma. dimming control there are three differe nt types of dim m ing control c i rc uits as follows : 1. using a pwm signal pwm bright ness co ntrol provides the wide st dimming ran ge by pulsi n g leds on a nd off at full and ze ro current, re pe ctively. the cha nge of avera ge le d cu rre nt de pe nds on th e d u ty cycle of the pwm si gnal. typical l y, a 0.1khz to 10khz pwm sign al is used. two appli c atio ns of pwm dimming with aic 1896 are sho w n in fi g 21. one, as fig. 21 (a), use s pwm sign al to drive shdn pin dire ctly for dimmin g control. the o t her, as fig. 21(b), emplo y s pwm sig nal going throu gh a re sisto r to d r i v e fb pin. if the shdn pin is u s ed, the increa se of duty cycle re sult s in led brig htne ss en han cem ent. if the fb pin is use d , on the cont rary, the increa se of duty cycle will decre ase its brig htne ss. in this appli c ation, leds
AIC1896 11 are dimme d by fb pin and turne d off completely by shdn . 2. using a dc voltage for som e ap plicatio ns, the preferred method of a dimming co n t rol u s e s a variabl e dc voltage to adju s t led current. a dimming co ntrol usin g a dc voltage is shown a s fi g. 22. as dc volta ge increa se s, th e voltage dro p over r2 in crea se s a nd the voltage drop over r1 decreases. cautio usly se lecting r2 an d r3 is e s sen t ial so that the current from the va ria b le dc so urce is m u ch small e r than t he led curre n t and mu ch l a rg er than the fb pin bi as current. with a vdc rangin g from 0v to 5v, the sel e ctio n of resisto r s in fig. 22 re sults in di mming control of led current fro m 20ma to 0ma, respectively. 3. using a filtered pwm signal filtered pwm signal ca n be con s id ere d as a n adju s table dc voltage. it can be u s e d to replace the variable dc voltage source in dim m ing co ntrol. the circuit is shown in fig. 23. zd 1 23.5v ~ 24.5v bz v5 5 - b2 4 r2 1k ? lx fb gnd ss s hdn in u1 a i c1896 l1 10 h c2 0. 033 f c1 4. 7 f on off 3. 3v t o 4. 2v v in d1 c h 521s -30 r1 62 ? c3 1 f i out =i led =20m a 6 4 1 3 5 2 s l f6025-100m 1r 0 fig. 20 white led driver with open-circuit protection lx fb gnd ss s hdn in a i c 1896 c2 0.033 f r1 62 r2 1k pw m zd 1 lx fb gn d ss s hdn in ai c 1 89 6 c2 0. 0 3 3 f r1 62 r2 1k pw m zd1 r3 30 k on off (a) (b) fig. 21 dimming control using a pwm signal
AIC1896 lx fb gnd ss shdn in a i c 1896 c2 0 . 033 f r1 82 r2 1k zd 1 r3 3. 3k v dc 0v ~ 5 v on of f 20m a ~ 0m a lx fb gn d ss shdn in a i c 1896 c2 0.033 f r1 82 r2 1k zd 1 r3 3.3k pw m c1 0.1 f 4k r4 on of f fig. 22 dimm ing co ntrol using a dc v o l t age fi g. 23 dimming control using a filtered pwm signal application examples c2 0 . 033 f lx fb gn d ss s hdn in u1 a i c189 6 l1 10 h d1 ch 521 s - 30 r1 62 ? zd 1 r2 1k ? c1 4.7 f on of f c3 1 f i out =i le d =20m a 3v t o 4. 2v 23.5v ~24.5v bz v5 5 - b2 4 v in r3 62 ? 6 4 1 3 5 2 s l f 602 5-10 0m 1r 0 fig. 24 1-cell li-ion powered driver for eight white leds with open-circuit protection 12
AIC1896 13 c a a2 b with p l atin g 25 a1 s e ct io n a- a b a s e m etal e1 d e aa e1 se e v i e w b e 0 0. 9 0 0. 3 0 1. 5 0 2. 60 2. 80 0. 0 8 0. 3 0 0. 0 5 e l1 l e1 c e e1 d b a2 a1 0 . 95 bsc 8 0. 60 1 . 90 b s c 0. 6 0 r e f 1. 3 0 1. 7 0 3. 00 3. 00 0. 22 0. 50 0. 15 0. 9 5 mi n . s y m b o l a1 . 4 ma x. so t- 2 6 mil l i m et e r s l x fb gn d ss shdn in a i c 189 6 l1 22 d2 bat5 4 c5 0.033 r2 135k c3 1 / 16 v c6 100 p r1 12k + 15v /5 m a 3v to 4.2v s l f6025- 220m r 7 3 c1 1 d1 bat5 4 s c2 1 / 16 v -15v/5m a c4 4.7 /6.3 v on of f v in v ou t 1 v out2 1 3 6 4 2 5 fig. 25 1-cell li-ion to 15v/5ma dual output converter for lcd bias physical dimensions (unit: mm) sot-23-6 5 vie w b
AIC1896 14 note : information provided by aic is believed to be accurate and reli able. however, we cannot assume responsibility for use of any circuitry other than circui try entirely embodied in an aic product; nor for any infringement of patents or other rights of thir d parties that may result from its use. we reserve the right to change the circuitry and spec ifications without notice. life support policy: aic does not authorize any aic product for use in life support devices and/or systems. life support device s or systems are devices or systems which, (i) are intended for su rgical implant into the body or (ii) support or sustain life, a nd whose failure to perform, when properly used in accordance with instructions for use provided in the labeling, can be reasonabl y expected to result in a signi ficant injury to the user.

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