View SC5014A_4613203.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

power management SC5014A high efciency 2-channel hb led driver with i 2 c interface and direct pwm dim ming revisionf2.0 features inputfvoltageff4.5vftof27vf outputfvoltageffupftof50v step-upf(boost)fcontroller ultra-fastftransientfresponsef(< 00s) programmablefswitchingffrequency linearfcurrentfsinks 2fstrings,fupftof240ma/string currentfmatchingf %f currentfaccuracyf2%f pwmfdimming directfpwmfdimming,f 000: fatf khz inputfdimmingffrequencyf 00hz-30khz 5-bitsfanalogfdimming i 2 cfinterface faultfstatusffopen/shortfled,fuvlo,fotp protectionffeatures open/shortedfled(s)fandfadjustablefovpf over-temperaturefandfuvlofshutdownfprotection 4mmfxf4mmf20-pinfqfnfpackage applications ultrabooks tm ,f all-in-onef pcs,f monitors,f automotive - displayfbacklighting backlightingfforfmid-sizefdisplays ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? description thefsc50 4afisfaf2-channel,fhighlyfintegrated,fhigh-ef - ciencyfstep-upf(boost)fhbfledfdriverfdesignedftofreducef thefthicknessfoffmid-sizeflcdfdisplays.fitffeaturesfafwidef inputfvoltagefrangef(4.5vftof27v),fdirectfpwmfdimming,f analogfdimming,faffexiblefoutputfconfguration,fanfi 2 cf interface,fandfnumerousfprotectionffeatures.f thefsc50 4afexhibitsf2%ftof4%fhigherfefciencyfwhenf usingfthefsamefsizefinductorsfasfexistingfledfdrivers.fbut,f unlikefexistingfdevices,fitfcanfalsofoperatefwithfinductorsf thatfarefupftof 0xfsmallerfwithoutfsacrifcingfefciency.f thisfpartfcanfalsofusefveryflow-proflefinductorsf(asfsmallf asf2.2h,f mmfheight),fwhichfallowsfledfdriversftofbef builtf directlyf intof thef lcdf panelf tof enablef ultra-thinf displays.f thef boostf controller,f withf programmablef switchingffffffff frequencyffromf200khzftof2.2mhz,fmaximizesfefciencyf byf dynamicallyf minimizingf thef outputf voltagef whilef maintainingf ledf stringf currentf accuracy.f itf providesfff excellentflinefandfloadfresponsefwithfnofexternalfcom - pensationfcomponents.fanfexternalfresistorfadjustsfthef currentffromf40-240mafperfstring.f u v l o e - p a d is e t f s e t s c p s c 5 0 1 4 a r 3 r 6 f l t c 3 r e f f l t v c c p g n d r 1 1 r 1 0 r 1 r 2 o v p io 2 r 9 r 8 v in = 4 . 5 to 2 7 v u p to 2 4 0 m a / s trin g io 1 io 1 io 2 c 5 r 5 p w m i p w m i s d a s c l f o r i 2 c e n e n l 1 q 1 r 4 n d r v c s d 1 v o u t u p to 5 0 v v c c = 4 . 5 to 5 . 5 v typical application circuit
SC5014A 2 pin confguration marking information ordering information device package sc50 4amltrt ()(2) mlpq-20f44 sc50 4aevb evaluationfboard notes: ()f availablefinftapefandfreelfonly.ffafreelfcontainsf3,000fdevices. (2)f lead-freefpackagingfonly.ffdevicefisfweeefandfrohsfcompliant,f andfhalogenffree. a g n d o v p 15 io 1 14 13 io 2 12 io 2 11 e n 20 c s 16 p g n d 17 18 v c c 19 u v l o 1 s c p 2 r e f 3 f s e t 4 n c 5 p w m i 10 i s e t 8 f l t 9 s d a 7 s c l 6 n d r v io 1 5 0 1 4 a yyw w xxxxx xxxxx nnnn = part number yyww = date code xxxxx = semtech lot no. xxxxx = semtech lot no.
SC5014A 3 exceedingfthefabovefspecifcationsfmayfresultfinfpermanentfdamageftofthefdeviceforfdevicefmalfunction.ffoperationfoutsidefoffthefparametersf specifedfinfthefelectricalfcharacteristicsfsectionfisfnotfrecommended. notes: ()f testedfaccordingftofjedecfstandardfjesd22-a 4-b. (2)ff calculatedffromfpackagefinfstillfair,fmountedftof3fxf4.5in,f4-layerffr4fpcbfwithfthermalfviasfunderfthefexposedfpadfperfjesd5 fstandards. absolute maximum ratings (refer to pgnd) vccfpinf(v)f f. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . f -0.3f tof +6.0 iofpinsf(v) f. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . f-0.3ffftofff+30 drvn,fovp,fcs,fen,fuvlo,fscp,fref,f flt f(v) f f. . f -0.3f tof +6.0 fset,fscl,fsda,fiset,fpwmif(v)f f. . . . . . . . . . . . . f -0.3f tof +6.0 pgndftofagndf(v) f. . . . . . . . . . . . . . . . . . . . . . . . . f-0.3ffftofff+0.3 esdfprotectionflevel () f(kv)f f. . . . . . . . . . . . . . . . . . . . . . . . . . . . f2 recommended operating conditions ambientftemperaturefrangef(c) f. . . . . . . . f-40f < ft a f < f+85 vinf(v) f f. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . f 4.5f tof 27f iofcurrentfperfstringff(ma)f f. . . . . . . . . . . . . . . . . . ff250f(max)f thermal information thermalfresistance,fjunctionftofambient (2)f (c/w)f f. . . . f 32 maximumfjunctionftemperaturef(c) f. . . . . . . . . . . . . . + 50 storageftemperaturefrangef(c) f. . . . . . . . . . . ff-65ftof+ 50 peakfirfrefowftemperaturef( 0sftof30s)f(c)f f. . . . . . +260 unlessfnotedfotherwise,ft a f=f25cfforftypical,f-40cf SC5014A 4 parameter symbol conditions min typ max units boostfoscillatorffrequency f sw r fset f=f00k 0.85 .5 mhz boostfoscillatorffrequency f osc r fsetf varies 0.2 2.2 mhz maximumfdutyfcycle d max 88 92 % control signals: en, pwmi, sda, scl highfvoltagefthreshold v ih v cc ff=f4.5vftof5.5v 2. v lowfvoltagefthreshold v il v cc ff=f4.5vftof5.5v 0.8 v sdafoutputflow v sda(l) -6maffromfv cc ftofsda 0.3 v pinfleakagefcurrent i leak v en f=f0v,fffv pwmi f=ffv iset f=fv fset f=fv sda f=fv scl f=f5.0v - a pwm dimming input pwmifinputfdimmingffrequency f pwmi 00 30k hz over-voltage protection ovpftripfthresholdfvoltage v ovp(trig) ovpfrisingf . .2 .3 v ovpfhysteresis v ovp(hys) ovpffallingf 0 mv ovpfleakagefcurrent i ovp(leak) ovpf=f5v 0. a current sink (io ) ioxfdimmingfminimumfpulsefwidth t pwm(min) f pwm(led)f =f 00hzf-f30khz 300 ns isetfpinfvoltage v iset .23 v regulationfvoltage v ion(reg) voltagefoffregulatingfstring 0.9 v currentfsinkfdisablefthreshold v ion(dis) checkedfatfpower-up 0.6 v currentfsinkfrise/fallftimef () t rise/fall r isingfedgeffromf 0%ftof90%foffi o(n) 25 ns ledfcurrentfaccuracy i on(acc%) pwmif=f00%,f t a =+25f c 96 200 204 ma ledfcurrentfmatchingf (2) i on(match) pwmif=f00%,f t a =+25f c f .0 % pwmif=f00%,f t a =-40f c,f+85 f c 2.0 % i on foffleakagefcurrent i on(leak) pwmif=f0v,fenf=f0v,fv io f=f25v 0. a electrical characteristics (continued)
SC5014A 5 electrical characteristics (continued) parameter symbol conditions min typ max units fault protection ledfshort-circuitfprotectionfthreshold v ion(scp) r 4f andfr 5f (3) 7xv scp 20xv scp 23xv scp v ledfopen-circuitfprotectionfthreshold v io_ocp 0.2 v ledfshort-circuitffaultfdelay t scp(delay) v ovpf setftof .5v,ff flt fgoesflow s flt fpinfleakagefcurrent i flt (leak) v en f=f0v,ffv flt f=ff5.0v - a flt foutputflow v flt (low) -5maffromf flt ftofv cc 0.3 v over-temperature protection thermalfshutdownftemperature t otp 50 c thermalfshutdownfhysteresis t otp-h 0 c i 2 c control interface: sda, scl timing specifcations sclfclockffrequency f scl 400 khz sclfclockflowfperiod t low(scl) .3 s sclfclockfhighfperiod t high(scl) 0.6 s holdftimefstartfcondition t hd(start) 0.6 s sdafsetupftime t su(sda) f 00 ns sdafholdftime t hd(sda) 0 0.9 s setupftimefstopfcondition t su(stop) 0.6 s busffreeftimefbetweenfstopf&fstart t bf .3 s notes: ()f ensuredfbyfdesignfandfcharacterization,fnotfproductionftested. (2 )f ledfcurrentfmatchingfforf2fchannelsfisfdefinedfasftheflargestfofftheftwofnumbers,fi.e.,f(max-avg)/avgfandf(avg-min)/avg;fwherefmaxfisfthef maximumfledfchannelfcurrent,fminfisfthefminimumfledfchannelfcurrentfandfavgfisfthefaveragefoffthef2fledfchannelfcurrents. (3)f referftofthefapplicationfcircuitfonfpagef20,ffiguref2.
SC5014A 6 pwm dimming linearity(30khz) ? ? ??? ??? ??? ? ?? ?? ? ?? ??? a??? ??? ??? ??? ch1 ch2 pwm dimming linearity(100hz) ? ? ??? ??? ??? ? ?? ?? ? ?? ??? a??? ??? ??? ??? ch1 ch2 ? ?? ? ?? ???? ?? ? ?? ? ? ?? ? ? ?? ? ?? ???? ?? ?? ???? ?? ? ?? ? ?? ???? ?? ??? ?????? ??? ??????? ??????? ??????? ??????? ??3?333????3??? ??3?333????3??? ??3?333????3??? ??3?333????3??? ???t??3????3 33???3?? ???t??3????3 33???3?? ???t??3????3 33???3?? ???t??3????3 33???3?? ?? ?? ?? ?? ???? ???? ???? ???? backlight efficiency vs. led string current 240ma/ch 120ma/ch typical characteristics v in (v) backlight efciency vs. input voltage backlight efciency vs. input voltage v in (v) backlight efciency vs. led string current backlight efciency vs. led string current led pwm dimming duty cycle (%) pwm dimming linearity pwm dimming linearity efciency(%) efciency(%) efciency(%) iout (ma) iout (ma) led pwm dimming duty cycle (%) efciency(%) ?? ???? ?? ? ?? ? ? ?? ? ??? ?????? ??? ? ?? ? ?? ???? ?? ? ?? ? ?? ???? ?? ? ?? ? ?? ???? ?? ??????? ??????? ??????? ??????? ?? ???? ?? ???t??3????3 33??? ???? ???? backlight efficiency vs. input voltage 240ma/ch 120ma/ch ?? ???? ?? ? ?? ? ? ?? ? ??? ?????? ??? ? ?? ? ?? ???? ?? ? ?? ? ?? ???? ?? ? ?? ? ?? ???? ?? ??????? ??????? ??????? ??????? ?? ?? ?? ?? ???t??3????3 33??? ???t??3????3 33??? ???t??3????3 33??? ???t??3????3 33??? ??? ??? ??? ??? ????? ????? ????? ????? backlight efficiency vs. input voltage 10s4p 7s4p ? ?? ? ?? ???? ?? ? ?? ? ? ?? ? ? ?? ? ?? ???? ?? ?? ???? ?? ? ?? ? ?? ???? ?? ??? ?????? ??? ??????? ??????? ??????? ??????? ??3?333????3??? ??3?333????3??? ??3?333????3??? ??3?333????3??? ???t??3????3 33???3???? ???t??3????3 33???3???? ???t??3????3 33???3???? ???t??3????3 33???3???? ?? ?? ?? ?? ???? ???? ???? ???? backlight efficiency vs. led string current 240ma/ch 120ma/ch v in =6v v in =12v 240ma/ch, 10s2p, 100hz dimming 240ma/ch, 10s2p, 30khz dimming 10s2p 240ma/ch led pwm dimming duty cycle (%) led pwm dimming duty cycle (%)
SC5014A 7 analog dimming 0 50 100 150 200 250 0 4 8 12 16 20 24 28 32 iled(ma) dec io3+4 current accuracy vs. temperature ??? ?????? ??? ?? ???? ?? ??? ?????? ??? ??? ?????? ??? ??? ?????? ??? ??? ?????? ??? ?? ???? ?? ??? ?????? ??? ?? ???? ?? ?? ???? ?? ? ?? ? ?? ???? ?? ?? ???? ?? ? ?? ? ?? ???? ?? ??? ?????? ??? ??3?3??3?????3?? ??3?3??3?????3?? ??3?3??3?????3?? ??3?3??3?????3?? ?????3?:? ?????3?:? ?????3?:? ?????3?:? a??? a??? a??? a??? ? ?? ? ??? ?????? ??? ??? ?????? ??? ???? ???? ???? ???? ??? ??? ??? ??? ???? ???? ???? ???? ???? ???? ???? ???? ? ?? ? ?? ???? ?? ??? ?????? ??? ?? ???? ?? ?? ???? ?? ??t? ? ??t? ? ??t? ? ??t? ? ?????t ?????t ?????t ?????t? ?? ? ?
??3???3 3???? ?
??3???3 3???? ?
??3???3 3???? ?
??3???3 3???? switching frequency vs. r fset led string current vs. r iset ? ?? ? ? ?? ? ??? ?????? ??? ?? ???? ?? ??? ?????? ??? ?? ???? ?? ??? ?????? ??? ? ?? ? ?? ???? ?? ?? ???? ?? ? ?? ? ?? ???? ?? ??? ?????? ??? ??? ?????? ??? ??? ?????? ??? ??? ??? ??? ??? ? ?? ? ??? ??? ??? ??? ?t? ?t? ?t? ?t? ?
??3???3 3? ?
??3???3 3? ?
??3???3 3? ?
??3???3 3? ??? ??? ??? ??? led string current matching vs. temperature ?? ???? ?? ?? ???? ?? ?? ???? ?? ?? ???? ?? ? ?? ? ?? ???? ?? ?? ???? ?? ? ?? ? ?? ???? ?? ?? ???? ?? ? ?? ? ?? ???? ?? ??? ?????? ??? ??3?3??3?????? ??3?3??3?????? ??3?3??3?????? ??3?3??3?????? ??????:? ??????:? ??????:? ??????:? temperature ( c) led string current matching vs. temperature led string current vs. r iset r fset (k ) switching frequency vs. r fset idac register value (in decimal format) led string current vs. analog dimming control register (idac) value led string current matching (%) boost switching frequency (khz) led string current (ma) typical characteristics (continued) v cc =5v, 240ma/ch r iset (k ) led string current (ma) led string current accuracy vs temperature temperature ( c) led string current accuracy (ma) v cc =5v, 240ma/ch 0.01 0.10 1.00 10.00 100.00 0.01 0.10 1.00 10.00 100.00 io(ma) duty(%) pwm direct (100hz, 30khz) 100hz 30khz 100hz 30khz led pwm dimming duty cycle(%) pwm dimming linearity output current (ma) 240ma/ch, 10s2p
SC5014A 8 vin start up testing condition: vin=12v,vcc=5v, leds=10s4p@100ma , 1mhz, 25 : :: : vin v_io1 iout vout start-up into short circuit protection vin /flt iout vout testing condition: vin=12v,vcc=5v, leds=10s4p@100ma , 1mhz, 25 : :: : , two leds short circuit unused string vin /flt iout vout testing condition: vin=12v,vcc=5v, leds=10s4p@100ma , 1mhz, 25 : :: : ,io1&io2 short to gnd start-up into leds open-circuit protection vin /flt iout vout testing condition: vin=12v,vcc=5v, leds=10s4p@100ma , 1mhz, 25 : :: : ,io1&io2 open time (5ms/div) led open circuit protection led short circuit protection start up by vin two leds short circuit in one string typical characteristics (continued) v in 8v/div. /flt 5v/div. v out 10v/div. i out 200ma/div. time (5ms/div) v in 8v/div. i out 100ma/div. v out 10v/div. /flt 5v/div. unused string time (5ms/div) time (5ms/div) 10s2p, 240ma/ch load transient response load transient response time (100us/div) time (100ms/div) starting with one led string open-circuit starting with one unused led string v in 8v/div. /flt 5v/div. v out 10v/div. i out 200ma/div. pwm(10khz)=0.5% to 99%, vin=12v, 200ma/ch x 2 load transient response testing condition: vin=12v, 25 : :: : , leds=10s4p@100ma/ch, 1mhz, pwmi=10khz, duty=0.5% to 99% v_io1 sda iout vout v io1 5v/div. pwmi 6v/div. v out 5v/div. i out 200ma/div. pwm(10khz)=99% to 0.3%, vin=12v, 200ma/ch x 2 v in 5v/div. i out 200ma/div. v out 10v/div. v io1 5v/div. load transient response testing condition: vin=12v, 25 : :: : , leds=10s4p@100ma/ch, 1mhz, pwmi=10khz, duty=99% to 0.3% v_io1 sda iout vout pwmi 6v/div. i out 200ma/div. v out 1v/div. v io1 5v/div.
SC5014A 9 led dimming testing condition: vin=12v, 25 : :: : , leds=10s4p@100ma/ch, 1mhz, pwmi=30khz, duty=4% v_io1 /flt iout vout led dimming testing condition: vin=12v, 25 : :: : , leds=10s4p@100ma/ch, 1mhz, pwmi=100hz, duty=0.04% v_io1 /flt iout vout analog dimming transient via i 2 c testing condition: vin=12v, 25 : :: : , leds=10s4p@100ma/ch, 1mhz, 100% to 9.68% v_io1 sda iout vout analog dimming transient via i 2 c testing condition: vin=12v, 25 : :: : , leds=10s4p@100ma, 1mhz, 0% to 100% v_io1 sda iout vout time (5ms/div) pwm dimming analog dimming transient via i 2 c analog dimming transient via i 2 c 0% to 100% dimming, 200ma/ch typical characteristics (continued) v io1 5v/div. pwm 6v/div. v out 1v/div. i out 200ma/div. time (10us/div) v io1 3v/div. i out 200ma/div. v out 1v/div. pwm 6v/div. pwm dimming time (100us/div) time (100us/div) 100% to 9.68% dimming, 200ma/ch line transient response line transient response time (500us/div) time (20ms/div) 0.04% dimming@100hz, v in =12v, 10s2p, 200ma/ch 4% dimming@30khz, v in =12v, 10s2p, 200ma/ch v io1 1v/div. sda 6v/div. v out 10v/div. i out 200ma/div. 7v in to 18v in , 200hz and 100% dimming duty, 200ma/ch line transient response v_io1 iout vin vout testing condition: vin fluctuation (7v to 18v), pwm dimming freq.=200hz, pwm dimming duty=100%; vin rising time 10us, 25 : :: : ; v io1 1v/div. i out 200ma/div. v out 1v/div. v in 5v/div. 7v in to 18v in , 200hz and 0.5% dimming duty, 200ma/ch sda 6v/div. i out 200ma/div. v out 10v/div. v io1 1v/div. line transient response v_io1 pwmi vin vout testing condition: vin fluctuation (7v to 18v), pwm dimming freq.=200hz, pwm dimming duty=0.5%; vin rising time >? >?>? >? 10us, 25 =? =?=? =? ; pwm 5v/div. v in 5v/div. v out 1v/div. v io1 1v/div.
SC5014A 0 pin descriptions pin # pin name pin function uvlo inputfunder-voltageflockoutfpinffdevicefisfdisabledfwhenfthisfpinfisflessfthanf .23vf(nominal).ffaddfafresistorf dividerffromfthisfpinftofthefinputfvoltagefandfagnd,frespectively. 2 scp short-circuitfledfprotectionfprogrammingfpinffshortedfledfprotectionfdisablesfthefindividualfchannelfwhenfthef currentfsinkfvoltagefexceedsfthefprogrammedfvoltagefthreshold.ffaddingfafresistorfdividerffromfthisfpinftofreffandf pgndfprogramsfthefshorted-ledfprotectionfupftof20xfthefv scp fvoltage.ffpullingfthefpinfhighftofvccfdisablesfthefscpf featurefonfallfchannels. 3 ref .23vfreferencefvoltagefoutputfpinffconnectfaf ffceramicfbypassfcapacitorffromfthisfpinftofground. 4 fset step-upf(boost)ffrequencyfsetfpinffconnectfafresistorffromfthisfpinftofgroundftofsetftheffrequencyffromf200khzftof 2.2mhz. 5 nc nofconnect.fthisfcanfbefleftffoatingforfconnectedftofgnd. 6 scl i 2 cfserialfclockfinputffthisfpinfmustfbefconnectedftofgroundfiffnotfused. 7 sda i 2 cfserialfdatafinputffthisfpinfmustfbefconnectedftofgroundfiffnotfused. 8 iset ledfcurrentfprogrammingfpinffconnectfanfexternalfresistorftofgroundftofprogramfthefcurrentfinfthefledfstrings.f forfmorefdetailsfpleasefreferftofledfstringfpeakfcurrentfprogrammingfon fpagef3. 9 flt logicflowffaultfstatusfpinffopen-drainfoutputfisflatchedflowfwhenffaultfconditionfisfdetected:fopen/shortfled,f shortedfstring,fovpforfotp.ffffaultfstatusfcanfbefresetfbyfremovingffaultfcondition(s)fandftogglingfthefen,fvccforf uvlofpins.fthisfpinfcanfbefleftffoatingfiffnotfused. 0 pwmi ledfstringfpwmfdimmingfcontrolfinput. f~4 io2f~fio regulatedfcurrentfsinkfledfchannelf2ftofchannelf frespectivelyf.fconnectfthefrelatedfiofpinftofthefcathodefoffthef bottomfledfinfstringf2ftofstringf frespectively.fconnectfthefrelatedfiofpinftofgroundftofdisablefthefrelatedfledf stringfduringfpowerfon. 5 ovp over-voltageffeedbackfpinffover-voltagefactivatedfwhenfpinfvoltagefexceedsf .2v.ffusefafresistorfdividerftiedftof thefoutputfandfgndftofsetfthefovpflevel. 6 cs step-upf(boost)fswitchfcurrentfsensefpinffconnectfafresistorffromfthisfpinftofgroundffforfcurrentfsensef-futilizedfinf peakfcurrentfmodefcontrolfloopfandfover-currentfsensefcircuitry. 7 pgnd powerfgroundfftiefthisfpinftofthefpowerfgroundfplanefcloseftofinputfandfoutputfdecouplingfcapacitors. 8 ndrv gatefdriveffforfthefexternalfstep-upf(boost)fn-channelfmosfet. 9 vcc inputfbiasfvoltagefsupplyfforftheficffacceptsf4.5-5.5vfinputs.ffaddfaf fforflargerfceramicfbypassfcapacitorffromf thisfpinftofground. 20 en logicfhighfenablefpinffpullflogicfhighftofenablefthefdeviceforfpullflowftofdisablefandfmaintainflowfshutdownf current. - pad agndfthermalfpadfforfheatsinkingfpurposesffitfshouldfbefconnectedftofgroundfplanefforfproperfcircuitfoperation.
SC5014A block diagram is e t e a m in im u m v o lta g e d e te ctio n o t p n d r v l s 4 io 1 io 1 io 2 o v p e n p w m i n c v c c l e d o p e n / s h o rt f a u lt s d a s c l o t p f s e t i 2 c in te rfa ce c s is e t a d ju st i - r e f a d j 5 - b it d a c u v l o b oo st o scilla tor v b g s c p r e f x 2 0 s c _ r e f i 2 c inte rface a nd l e d c o n trol l og ic c o ntro l l og ic f l t o c / s c d e te ctio n s c _ r e f io 2 c o m p 5 4 o s c c l im + + - p w m c o m p s lo p e c o m p p g n d 4 d c d c b g ilim + - + - o v p + -
SC5014A 2 general description thefsc50 4afcontainsfafhighffrequency,fcurrent-mode,f internallyfcompensatedfboostfcontrollerfwithf2fconstantf currentfsinksfforfdrivingfledfstrings.ffthefledfcurrentfforf bothfstringsfisfprogrammedfbyfanfexternalfresistor.fthef boostfconverterfoperatesftofmaintainfminimalfrequiredf outputfvoltagefforfregulatingfthefledfcurrentftofthefpro - grammedfvalue.ffaftypicalfbacklightfapplicationfusesf3ftof 4fledsfperfeachfstring,fwithfcurrentfdrivenfupftof240ma. f thefuniquefcontrolfloopfoffthefsc50 4afallowsffastftran - sientffresponsefinfdealingfwithflinefandfloadfdisturbances. thefsc50 4a,foperatingfwithfanfexternalfpowerfmosfet,f regulatesfthefboostfconverterfoutputfvoltagefbasedfonf thefinstantaneousfrequirementfoffthef2fstringfcurrentf sources.fthisfprovidesfpowerftofthefentireflightingfsubsys - temfwithfincreasedfefciencyfandfreducedfcomponentf count.ffitfsupportsfpwmfdimmingffrequenciesffromf 00hzf tof30khzfandfthefsupplyfcurrentfisfreducedftof2maftypicalff whenfbothfledfstringsfarefof.ff start-up whenfthefenfpinfisfpulledfupfhighf(>2. v),fthefdevicefisf enabledfandfthefuvlofandfvccfpinfvoltagesfarefchecked.f thefvccfvoltagefhasffxedfunder-voltagefrisingfandffallingf tripfpoints.fiffthefvccfpinfisfhigherfthanf4.2vfandfthefuvlof pinfvoltagefisfgreaterfthanf .23v,fthefsc50 4afgoesfintofaf start-upfsequence.fthefuvlofpinfvoltagefcanfbefusedftof programf thef inputf powerf sourcef voltagefvinf turn-onf thresholdfandfitsfhysteresisf(referftofthefdetailedfapplica - tionfcircuitfonfpagef20,ffiguref2)fasfshownfbyftheffollow - ingfequations: f v in_turnon f[v]f=f .23fxf(r f +fr 2 )f/fr f v in_hysteresis f[v]f=f 0 -5 fxfr 2f [] infthefnextfphase,fthefsc50 4afchecksfeachfiofpinftof determinefiffthefrespectivefledfstringfisfenabled.feachfiof pinfisfpulledfupfwithfaf 00 a fcurrentfsource.fiffanyfiofpinf isfconnectedftofground,fitfwillfbefdetectedfasfanfunusedf string,fandfwillfbefturnedfof.fthisfunusedfstringfcheckingf procedureftypicallyftakesf ms.fafterfthis,fthefsc50 4af entersfintofafsoft-startfsequence. thefsoft-startffunctionfhelpsftofpreventfexcessfinrushf currentfthroughfthefinputfrailfduringfstart-up.finfthef sc50 4a,fthefsoft-startfisfimplementedfbyfslowlyframpingf upfthefreferencefvoltageffedftoftheferrorfamplifer.fthisf closedfloopfstart-upfmethodfallowsfthefoutputfvoltagef toframpfupfwithoutfanyfovershoot.fthefdurationfoffthef soft-startfinfthefsc50 4afisfcontrolledfbyfanfinternalf timingfcircuit,fwhichfisfusedfduringfstart-upfandfisfbasedf onfthefboostfconverterfswitchingffrequency.fforfexample,f withfswitchingffrequencyfatf mhz,fitfisf8msftypicalfandf becomesf4msftypicalfwhenfthefswitchingffrequencyfisf 2mhz.ff iffthefpwmfvoltagefgoesflowfwhilefthefsc50 4afisfinfsoft- startfoperation,fthefsc50 4afswitchesftofstandbyfmode,f wherefthefexternalfpowerfmosfetfandfthefledfcurr entf sourcesfwillfbefturnedfoffimmediately.fthefinternalfsoft- startftimerfisfturnedfoffandfthefsoft-startfvaluefisfsaved.f whenfthefpwmfvoltagefgoesfhighfagain,fthefsoft-startf resumesffromfthefpreviouslyfsavedfvalue. eachfledfcurrentfsourceftriesftofregulatefthefledfcurrentf tofitsfsetfpoint.fthefcontrolfloopfwillfregulatefthefoutputf voltagefsuchfthatfallfthefiofpinfvoltagesfarefatfleastf0.9vf typical. shutdown whenfthefenfpinfisfpulledfdownfbelowf0.8v,fthefdevicef entersfintofshutdownfmode.finfthisfmode,fallfthefinternalf circuitryfisfturnedfoffandfthefsupplyfcurrentfisflessfthanf af(max).f infthefscenariofwherefthefenfpinfvoltagefisfhigh,fbutfvccf voltageffallsfbelowfthefrespectivefuvlofthreshold,fthef sc50 4afgoesfintofafsuspendfmode.finfthisfmode,fallfthef internalfcircuitryfexceptfthefreferencefandfthefoscillatorf arefturnedfof. thermal shutdown (tsd) iffthefthermalfshutdownftemperaturefofftypicalf 50cfisf reached,fthefboostfconverterfandfallfiofcurrentfsourcesf arefturnedfof.fthef flt fpinfisfforcedflowfinfthisfcondition.ff whenftheftemperatureffallsfbelowftheftsdftripfpointfbyf 0c,f thef sc50 4af willf restartf followingf thef start-upf sequencefasfdescribedfbefore.fthef flt fpinfisflatchedffandf willfstayflow,fitfisfresetfbyfcyclingfthefen,fvccforfuvlo.f applications information
SC5014A 3 applications information (continued) boost converter operation thefsc50 4afincludesfafboostfcontrollerfwithfprogram - mablefswitchingffrequency.fitfappliesfafcurrent-modef controlfmethodfwithfanfintegratedfcompensationfloopfasf shownfinfthefdiagramfbelow.fthefclockf(seefblockfdiagramf onfpage )ffromfthefoscillatorfsetsftheflatchfandfturnsfonf thefexternalfpowerfmosfet,fwhichfservesfasfthefmainf powerfswitch.fthefcurrentffowingfthroughfthisfswitchfisf sensedfbyfthefcurrentfsensefresistorfinfseriesfwithfthef switch.fthefsensedfswitchfcurrentfisfsummedfwithfthef slope-compensatedframpfandffedfintofthefmodulatingf inputf off thef pwmf comparator.fwhenf thef modulatingf rampfintersectsftheferrorfampliferfoutputf(comp),fthef latchfisfresetfandfthefpowerfmosfetfisfturnedfof.ffthef sensefresistorfalsofsetsfthefpeakfcurrentflimitfoffthefpowerf mosfet,fi ocp fusingftheffollowingfequation: f i ocp [a]f=f0.4f/fr csf [] e a m in . v o lta g e d e te ctio n b o o st o scilla to r c o n tro l l o g ic c o m p o s c + + - p w m c o m p s lo p e c o m p d c + - v in = 4 . 5 v to 2 7 v io c 5 l 1 q 1 r 4 d 1 l s c s n d r v thefcurrent-modefcontrolfsystemfcontainsftwofloops.fforf thefinnerfcurrentfloop,ftheferrorfamplifierf(ea)foutputf (comp)fcontrolsfthefpeakfinductorfcurrent.finfthefouterf loop,fthefeafregulatesfthefoutputfvoltagefforfdrivingfthef ledfstrings.f boost converter switching frequency selection thefresistorfbetweenffsetfandfgndfsetsfthefboostfcon - verterfswitchingffrequencyf(200khzftof2.2mhz)fusingfthef followingfequation: f f sw f[khz]f=f 0 5 /fr fsetff [k] afhigherfswitchingffrequencyfallowsfthefusefofflow-proflef heightfinductorsfforfspace-constrainedfandfcost-sensitivef applications.ff over-voltage protection (ovp) thefsc50 4afffeaturesfprogrammablefoutputfover-voltagef protectionftofpreventfdamageftoftheficfandfoutputfcapaci - torfinfthefeventfoffafledfstringfopen-circuit.fthefboostfcon - verterfoutputfvoltagefisfsensedfatfthefovpfpinfthroughffthef resistorfvoltagefdivider.fthefovpftripfthresholdf(referftof detailedfapplicationfcircuitfonfpagef20,ffiguref2)fcanfbefcal - culatedfusingftheffollowingfequation: f ovpftripfvoltagef[v]f=f .2fxf(r f+fr 2 )f/fr 2 whenfthefovpfpinfvoltagefexceedsf .2v,fthefboostfcon - verterfturnsfoffandfthef flt fpinfisfpulledflow.fwhenfthef ovpfpinfvoltageffallsfbelowfthefovpfthresholdf(falling),f thefboostfconverterfrestartsfandfthef flt fpinfisfreleased.f therefisf 0mvfhysteresisfbetweenfthefovpfpinfthresholdf (falling)fandfthefovpfpinfthresholdf(rising).fthisfresultsfinf anfoutputfvoltagefhysteresisfexpressedfas:f ffffffoutputfovpfhysteresisf[mv]f=f 0fxf(r f +fr 2 )f/fr 2 led current sink thefsc50 4afprovidesf2fcurrentfsinksfandfeachfcanfsinkf upftof240mafcurrent.ffitfincorporatesfledfstringfshort- circuitfprotectionf(trip-levelfprogrammable;fcanfbefdis - abled)fandfledfstringfopen-circuitfprotection. led string peak current programming ledfstringfpeakfcurrentf(atf 00%fdimming)fcanfbefsetfbyf selectingfresistorfr iset ,ffconnectedfbetweenfisetfandfgnd.f thefrelationshipfbetweenfr iset fresistancefandfsinglefledf stringf peakf currentf isf calculatedf usingf thef followingf equation: f i led f[ma]f=f2fxf( 036fxf.23)f/fr isetf [k]f thefstringfcurrentfcanfbefprogrammedfupftof240ma. led connection twofstringsfoffledsfcanfbefconnectedftofpinfio fandfpinf io2.fpinsfio ,2fshowedfstayfconnected.f unused strings thefsc50 4afmayfbefoperatedfwithflessfthanf2fstrings.ffinf thisfmodefoffoperation,fthefunusedfiofpinfshouldfbefcon - nectedftofground.fduringfstart-up,fthesefunusedfstringsf arefdetectedfandfdisabledfwhilefotherfactivefstringsfworkf normally,fandf flt fdoesfnotf getf pulledflow.
SC5014A 4 led short-circuit protection (scp) thefsc50 4affeaturesfafprogrammablefledfshort-circuitf protectionf(scp).fthisfallowsfthefpartftofbefcustomizedf basedfonftheffledfforwardfvoltagef(v f )fmismatchesfbetweenf thefledfstrings.fiffoneforfmorefledsfarefdetectedfasfshort- circuited,fthefcorrespondingfstringfwillfbeflatchedfof.ffthef voltagesfonfbothfiofpinsfarefmonitoredftofcheckfiffanyfiof pinf exceedsf thef scpf tripf point.fthef iof voltagef forf ledf string(s)fwithffaultyfshort-circuitfled(s)fwillfbefhigherfthanf otherfnormalfiofpinfvoltage.ffthisfledfshort-circuitfprotec - tionftripflevelf(seefdetailedfapplicationfcircuitfonfpagef20,ffff figuref2)fisfexpressedfbyftheffollowingfequation: f v scp_trip f[v]f=f20fxf( .23fxfr 4 )f/f(r 4 f+fr 5 ) iffanyfiofpinfvoltagefexceedsftheftripfvoltage,fthefiofcurrentf sinkfwillfbeflatchedfoffandfthef flt fwillfgoflow.fthisflatchfcanf befresetfbyfcyclingfuvlo,fvccforfen.fotherfledfstringfisf unafectedfandfcontinuefinfnormalfoperation.fthisfprotec - tionfwillfbefdisabledfiffscpfisftiedftofvcc.f therefisfaftypicalf 0sfscpfdetectionftime fin fpwmfdimmingf applications.fiffthefpwmfdimmingfon-timefisflessfthanfthef scpfdetectionftime,fthefscpfcannotfbefenabled. infmanyfapplications,fledfstringsfarefconnectedftofthefiof pinsfthroughfafmechanicalfconnector,fwhichfcannotfsupportff anfelectricalfconnectionfatfspecifcftimes.fthisfconnectionf mightfcausefnoisefonfthefiofpins.fiffthisfnoisefisflargefenough,f itfmayftriggerfaffalsefscpfmode.funderfsuchfcondition,faf ceramicfdecouplingfcapacitorf( 00pff~f8.2nf)fbetweenfiof pinftofgroundfcanfhelpfpreventfthefsc50 4affromfenteringf thefprotectionfmodefbyffalseftrigger.for,fsimplyfdisablefthisf featurefbyfconnectingfscpfpinftofvccfpin. led open-circuit protection iffanyfledfstringfbecomesfopen,fthefrespectivefiofpinf voltagefwillfbefpulledftofground.fconsequently,fthefinter - nalfcompfnodef(outputfofferrorfamplifer)fisfdrivenfhigh,f whichfcausesfthefboostfoutputfvoltageftofincrease.fthef outputfvoltagefwillfbefeventuallyfclampedftofafvoltagefsetf byfthefovpfresistorfdivider.funderfthisfcondition,ftheffaultyf stringfisflatchedfoffandfthef flt fpinfisfpulledflow.fthefboostf voltagefgetsfregulatedftofthefvoltagefrequiredftofsetfallf non-faultyf iof pinsf abovef 0.9vf (typ).fthef otherf stringf remainfinfnormalfoperation.fthef flt fandftheffaultyfledf applications information (continued) currentfsinkflatch-offcanfbefresetfbyfcyclingfuvlo,fvccforf en. led analog dimming control thefledfcurrentfinfsc50 4afcanfbefdimmedfviafthef5-bitf analogfdimmingfregisterf(registerfaddress:f0x02).fthefledf currentfcanfbefadjustedfinf32fstepsffromf0maftofmaximumf value,fwhichfisfdeterminedfbyfthefr iset fresistor. thefsc50 4afhasfafuniquefdacfarchitecturefwhichfallowsf itftofhavefexcellentfledfcurrentfaccuracyfandfstring-to- stringfmatchingfoverfthefentirefdacfrange.f thefanalogfdimmingfmethodfcanfbefusedfinfconjunctionf withfpwmfdimmingftofincreasefthefdimmingfresolution. f theffastfloopfresponsefoffthefsc50 4afallowsfthefledf currentftoftransitionftofafnewfvaluefwithinf 60sforfso.f pleasefreferftofthefgraphsfinftheftypicalfcharacteristicsf section. led pwm dimming control thefpwmfinputfneedsftofbefheldfhighfforfnormalfopera - tion.ffpwmfdimmingfcanfbefachievedfbyfcyclingfthefpwmf inputfatfafgivenffrequencyfwherefaflowfonfthefpwmf inputfturnsfoffbothfiofcurrentfsinksfandfafhig hfturnsfonf allfiofcurrentfsinks.ffthefpwmfpinfcanfbeftoggledfbyfexter - nalfcircuitryftofallowfpwmfdimming.ffinfaftypicalfapplica - tion,f af microcontrollerf setsf af registerf orf counterf thatf variesfthefpulsefwidthfonfafgpiofpin.ffthefsc50 4afallowsf dimmingfoverfafwideffrequencyfrangef( 00hz-30khz)finf orderftofallowfcompatibilityfwithfafwidefrangefoffdevices.f thisfincludesfthefnewestfdimmingfstrategiesfthatfavoidf thefaudiofbandfbyfusingfhighffrequencyfpwmfdimming.f infthisfmanner,fafwidefrangefoffilluminationfcanfbefgener - atedf whilefkeepingfthefinstantaneousfledfcurrentfatfitsf peakfvaluefforfhighfefciencyfandfcolorftemperature.ffthef sc50 4afprovidesfaf 000: fdimmingfrangefatf khzfpwmf frequency.fthefledfcurrentfsinksfturnfon/offveryfrapidlyf (<25ns,ftypical).ffthisfallowsfafwidefdimmingfratio.fanf additionalfadvantagefoffpwmfdimmingfisfthatfitfavoidsfin- rushfcurrentsfwhenffillingfthefboostfoutputfcapacitor.f simplyfapplyfthefpwmfsignalftofthefdevicefatf 0%fdutyfforf afmillisecondforftwo,fandfin-rushfcurrentfisfreduced.ffthisf dimmingftimefwillfvaryfbasedfonfthefnumberfoffledsfandf thefsizefoffthefoutputfcapacitor.fthisfcanfbefeasilyfdeter - minedfduringftestingfandfprogrammedfintofthefmicrocon - trollerffrmware.
SC5014A 5 table 1 fault p rotection descriptions type of fault user disable? fault criteria action on fault recovery device flt pin (latching / non-latching condition(s) flt pin inputf under-voltagef atfvin f (uvlo) no v in ff.23vf f (rising) high no v in ff.23vf f (rising) high inputf f under-volt - agefatfvccf f (uvlo) no vccff4.2v f (rising) high no vccff4.2v f (rising) high over-voltagef protectionf (ovp) no v ovp f>f.23v f (rising) regulateftofovpf threshold: f i o(n) f=fon low f (non-latching) v ovp ff0.4v limitfq ffetfdrainf currentff0.4v high shortedf led(s) yes,ftief scpftof vcc v io(n) f>f20fxfv scp devicefon: f i o(n) f=fof f otherfi o(all) f=fon low f (latching) replacefshortedf led(s)fandftogglef en,fvccforfuvlo high v io(all) f>f20fxfv scp deviceflatch-of; f i o(all) f=fof low f (latching) replacefshortedf led(s)fandftogglef en,fvccforfuvlo high open f led(s) no v io(n) ff 50ocf(typ) devicefof; f i o(all) f=fof low f (latching) satisfyft hys f>f0oc; f devicefon; i o(all) f=fon; f togglefen,fvccforf uvlo high note:ffreferftofthefapplicationfcircuitfexamplefforfr fandfr 2 fonfpagef20,ffiguref2 .
SC5014A 6 applications information (continued) fault protection thef sc50 4af providesf faultf detectionf forf lowf supplyf voltage,fledfrelatedffaults,fboostfconverterfover-voltagef andfthermalfshutdown.fthefopenfdrainfoutputfpinf( flt )f indicatesfafsystemffa ult.fthefnaturefofftheffaultfcanfbefreadf fromftheffaultfstatusfresistorf(registerfaddress:f0x00)fviafi 2 cf interface.freferftoftablef fforfafdescriptionfoff theffaultf protectionfmodes. other possible confgurations dependingfonfdifferentfapplicationfrequirements,fthef sc50 4afcanfalsofbefeasilyfconfguredftofotherftopolo - gies,fsuchfasfthefsepicfconfgurationfshownfinffiguref4,f pagef2.f li-ion powered display confguration iffafli-ionfpoweredfdisplayfapplicationfisfrequired,fv cc f fisf neededftofpowerfwithf5v.fhowever,fv in fcanfbefsetflowerf fromf3vftof4.2vfforfexample.fanfadvantagefoffthisftypefoff confgurationfisfthatfitfprovidesfhigherfefciency.ffpleasef useffiguref3fonfpagef20fforfreference. high output voltage confguration iffafhighfoutputfvoltagefapplicationfisfrequired,fanfaddi - tionalfexternalfcascodefmosfetfcanfbefaddedfonfeachfiof pinftofmeetfsuchfrequirement,fpleasefreferftoffiguref5fonf pagef2 fforfreference. infthisfcase,fthefupperflimitfonfthefoutputfvoltagefisfmainlyf determinedfbyfthefratingfoffthefexternalfmosfet,fheatf dissipation,fetc. pcb layout considerations thefplacementsfoffthefpowerfcomponentsfoutsidefthef sc50 4afshouldffollowftheflayoutfguidelinesfoffafgeneralf boostfconverter.fthefdetailedfapplicationfcircuitfisfusedf asfanfexample. capacitorf(c2)fshouldfbefplacedfasfclosefasfpossibleftof thefvccfandfagndftofachievefthefbestfperformance. capacitorf(c )fisfthefinputfpowerfflteringfcapacitorfforf thefboost.fitfneedsftofbeftiedftofpgnd. . 2. thefconverterfpowerftrainfinductorf(l )fisfthefboostf converterfinputfinductor.fusefwidefandfshortfftracesf connectingfthesefcomponents. thefoutputfrectifyingfdiodef(d )fusesfafschottkyfdiodef forffastfreversefrecovery.ftransistorf(q )fisfthefexternalf switch.fresistorf(r9)fisfthefswitchfcurrentfsensingfresis - tor.ftofminimizefswitchingfnoisefforfthefboostfcon - verter,fthefoutputfcapacitorf(c6)fshouldfbefplacedf suchfthatfthefloopfformedfbyfq ,fd ,fc6fandfr9,fisf minimized.fthefoutputfoffthefboostfconverterfisfusedf tofpowerfupfthefleds.fusefwidefandfshortftracefcon - nectingfpinfndrvfandfthefgatefoffq .fthefgndsfforfr9f andfc6fshouldfbefpgnd.fthesefcomponentsfshouldf befcloseftofthefsc50 4a. resistorf(r8)fisfthefoutputfcurrentfadjustingfresistorf forfio fthroughfio2fandfshouldfreturnftofagnd.fplacef itfnextftofthefic. resistorf (r6)f isf thef switchingf frequencyf adjustingf resistorfandfshouldfreturnftofagnd.fplacefitfnextftof thefic. thef decouplingf capacitorf (c3)f forf pinf reff shouldf returnftofagnd.fplacefitfnextftofthefic. resistorsf(r4,fr5)fformfafdividerftofsetfthefscpflevel,fr4f shouldfreturnftofagnd.fplacefitfnextftofthefic. resistorsf(r2,fr )fformfafdividerftofsetfthefuvloflevelf forfuvlofpin.fr fshouldfreturnftofagnd.fplacefitfnextf tofthefic. r fandfr 0fformfafdividerftofsetfthefovpflevelfforf vout,fr 0fshouldfreturnftofagnd.fplacefitfnextftofthef ic. allftheftracesfforfcomponentsfwithfagndfconnectionf shouldfavoidfbeingfroutedfcloseftofthefnoisyfareas. anf exposedf padf isf locatedf atf thef bottomf off thef sc50 4afforfheatfdissipationfandfanalogfground.faf copperfareafunderneathfthefpadfisfusedfforfbetterf heatf dissipation.f onf thef bottomf layerf off thef pcbf anotherfcopperfarea,fconnectedfthroughfviasftofthef topflayer,fisfusedfforfbetterfthermalfperformance.fthef padfatfthefbottomfoffthefsc50 4afshouldfbefcon - nectedftofagnd.fagndfshouldfbefconnectedftofpgndf atfafsinglefpointfforfbetterfnoisefimmunity. 3. 4. 5. 6. 7. 8. 9. 0. . 2.
SC5014A 7 components selection inductor selection thefchoicefoffthefinductorfafectsfthefconvertersfsteadyf statefoperation,ftransientfresponse,fandfitsfloopfstability.f specialfattentionfneedsftofbefpaidftofthreefspecifcationsf offthefinductor,fitsfvalue,fitsfdcfresistancefandfsaturationf current.fthefinductorsfinductancefvaluefalsofdeterminesf thef inductorf ripplef current.fthef boostf converterf willff operatefinfeitherfccmf(continuousfconductionfmode)forf dcmf(discontinuousfconductionfmode)fdependingfonfitsf operatingfconditions.fthefinductorfdcfcurrentforfinputf currentfcanfbefcalculatedfusingftheffollowingfequation. v i v i in out out in = i in - input current;i out C output current; v out C boost output voltage; v in C input voltage; C effciency of the boost converter thenfthefdutyfratiofunderfccmfisfshownfbyftheffollowingf equation. d out d in out v v v v v d + + ? = v d fCfforwardfconductionfdropfofffoutputfrectifyingf diode f whenfthefboostfconverterfrunsfunderfdcmf(flffl boundary ),fnormallyf thefconverterfhasfhigherf efciency. whenfselectingfanfinductor,fanotherffactorftofconsiderfisf thefpeak-to-peakfinductorfcurrentfripple,fwhichfisfgivenf byftheffollowingfequation: l f d v i sw in l = usuallyfthisfpeak-to-peakfinductorfcurrentfripplefcanfbef chosenfbetweenf30%ftof50%foffthefmaximumfinputfdcf current.fthisf givesf thef bestf compromisef betweenf thef inductorfsizefandfconverterfefciency.fthefpeakfinductorf currentfcanfbefcalculatedfusingftheffollowingfequation: l f 2 d v i i sw in in peak -l + = forfmostfapplications,fanfinductorfwithfafvaluefoff2.2 hftof 22 hfshouldfbefacceptable,f(referftofthefdetailedfapplica - tionf circuitf onf pagef 20,f figuref 2).fthef inductorf peakf currentfmustfbeflessfthanfitsfsaturationfrating.fwhenfthef inductorfcurrentfisfcloseftofthefsaturationflevel,fitsfinduc - tancefcanfdecreasef20%ftof35%ffromfthef0afvaluefdepend - ingfonfthefvendorfspecifications.ffusingfafsmallfvaluef inductorfforcesfthefconverterfinfdcm,finfwhichfcasefthef inductorfcurrentframpsfdownftofzerofbeforefthefendfoff eachfswitchingfcycle.fitfreducesfthefboostfconvertersf maximumfoutputfcurrentfandfproducesfaflargerfinputf voltagefripple.fthefdcrfoffthefinductorfplaysfafsignifcantf rolefforftheftotalfsystemfefciencyfandfusuallyftherefisfaf trade-offf betweenf thef dcrf andf sizef off thef inductor.ffffff tablef 2f listsf somef recommendedf inductorsf andf theirf vendors. ffffffffffffffffffffff tablef2.ffrecommendedfinductors inductor vendorfwebsite hcm0703,f2.2uh~0uh www.cooperindustries.com ihlp-2525cz-0 ,f4.7uh~0uh www.vishay.com mlpc0730l,f2.2uh~4.7uh www.nec-tokin.com/english output capacitor selection thefnextfdesignftaskfisftargetingfthefproperfamountfoff outputfripplefvoltagefdueftofthefconstant-currentfledf loads.fusuallyfx5rforfx7rfceramicfcapacitorfisfrecom - mended.fthefceramicfcapacitorfminimumfcapacitancef neededfforfafgivenffripplefcanfbefestimatedfusingftheffol - lowingfequation: ( ) ripple sw out out in out out v f v i v v c ? =
SC5014A 8 application information (continued) v ripple C peak to peak output ripple. thefripplefvoltagefshouldfbeflessfthanf200mvf(pk-pk)ftof ensurefgoodfledfcurrentfsinkfregulation.fforfexample,faf typicalfapplicationfwheref240ma/stringfcurrentfisfneeded,f theftotalfoutputfcurrentfforf2fchannelsfwillfbef480ma,fandf 6xf4.7 fffcapacitorsfarefrecommended. duringfloadftransient,fthefoutputfcapacitorfsuppliesforf absorbsfadditionalfcurrentfbeforefthefinductorfcurrentf reachesfitsfsteadyfstatefvalue.flargerfcapacitancefhelpsf withfthefovershoot/undershootfduring loadftransientfandf loopfstability.f input capacitor selection x5rforfx7rfceramicfcapacitorfisfrecommendedfforfinputf bypassfcapacitor.ffaf ffcapacitorfisfsufcientfforfthefvccf input.fbypassfthefvinfinputfwithfaf 0 fforflargerfceramicf capacitor. output freewheeling diode selection schottkyfdiodesfarefthefidealfchoicefforfthefsc50 4afduef tof theirf lowf forwardf voltagef dropf andf fastf switchingf speed.fftablef3fshowsfseveralfdiferentfschottkyfdiodesf thatfworkfproperlyfwithfthefsc50 4a.fverifyfthatfthefdiodef hasfafvoltagefratingfgreaterfthanfthefmaximumfpossiblef outputfvoltage.fthefdiodefconductsfcurrentfonlyfwhenf thefpowerfswitchfisfturnedfof.fthefdiodefmustfbefratedftof handlefthefaveragefoutputfcurrent.fafdiodefratedfforf af averagefcurrentfwillfbefsufcientfforfmostfdesigns. tablef3.ffrecommendedfrectiferfdiodes rectiferfdiode vendorfwebsite dfls40 www.diodes.com ss4/5/6,fss24/25/26 www.vishay.com external power mosfet selection thefboostfconverterfinfsc50 4afusesfanfexternalfpowerf mosfetftofregulatefthefoutputfvoltagefandfoutputfpowerf tofdrivefledfloads.ffthisfboostfswitchingfstructurefhasfanf advantagefinfthatfthefsc50 4afisfnotfexposedftofhighf voltage.ffonlyfthefexternalfpowerfmosfet,ffreewheelingf diodefandfthefinductorfwillfbefexposedftofthefoutputf voltage.fthefexternalfpowerfmosfetfshouldfbefselectedf withfitsfvoltagefratingfhigherfthanfthefoutputfvoltagefbyf minimumf30%.fthefcurrentfratingfshouldfbefenoughftof handlefthefinductorfpeakfcurrent.flowfr ds (on)fmosfetsf arefpreferredfforfachievingfbetterfefciency. thef gdf (gatef driver)f onf sc50 4af providesf af (peak)f currentf drivingf capabilityf whichf isf suitablef forf mostf mosfetsf forf highf frequencyf operation.f thef averagef currentfrequiredftofdrivefthefmosfetfisfgivenfbyftheffol - lowingfequation. i gate = q g x f sw q g gate charge thefr ds(on) fandfitsfrmsfcurrentfi s_rms foffthefpowerfmosfetf willfgeneratefthefconductionflossfusingftheffollowingf equation. p cond = i s_rms 2 x r ds(on) thefmosfetsfswitchflossfcanfbefcalculatedfusingftheffol - lowingfequation. p sw = ? x v in x i l_peak x f sw x (t on + t off ) where t on and t off are the mosfets on and off time and they can be estimated by the following equations. ( ) ( ) g plateau gd r on r / v q t t + ? + = 5 5 ( ) g plateau gd f off r / v q t t + + = 5 whereft r ,ft f ,fq gd fandfv plateau fcanfusuallyfbeffoundffromfdata - sheetfoffthefselectedfmosfet.fr g fisfthefresistancefoffthef optionalfresistorfconnectedfinfseriesfonfthefgatefoffthef mosfet.
SC5014A 9 components selection (continued) current sensing resistor selection thefswitchfcurrentfisfsensedfviafthefcurrentfsensingfresis - tor,fr cs .fthefsensedfvoltagefatfthisfpinfisfusedftofsetfthef peakfswitchfcurrentflimitfandfalsofusedfforfsteadyfstatef regulationfoffthefinductorfcurrent.fthefcurrentflimitfcom - paratorfhasfaftripfvoltagefoff0.4vf(typical).fr cs fvaluefisf chosenftofsetfthefpeakfinductorfandfswitchfcurrentfusingf theffollowingfequation. i 2 sw(peak) = 0.4/r cs thefpowerfdissipationfinfr cs fcanfbefcalculatedfusingfthef followingfequations. p r_cs = i rms 2 x r cs i rms = d x [i o /(1-d)] 2 i o = output dc current, d = duty cycle forftheftypicalfapplicationfcircuitfshownfinfthefdetailedf applicationfcircuitf(pagef20,ffiguref2),fthefpowerfdissipa - tionfonfthefsensingfresistorfisfshownfbyftheffollowingf equations. assumingfv in f=f6vfandfv out f=f3 .5v,fthusfdf=f8%, p r_cs = 0.81 x (0.48/0.19) 2 x 0.08 = 0.414(w) forfthisfexample,faf0.08ff %fthick-flmfchipfresistorfratedf atf wfcanfbefused.
SC5014A 20 figure 2 application circuit example, 20 led @ 200ma v in ( 12 - 19 v ) s c 5014 a vcc en uvlo scp r e f f s e t scl sda i s e t pwm io 2 io 2 io 1 io 1 ovp c s p g n d n d r v r 4 r 3 c 6 q 1 c 12 sda r 8 r 15 c 1 scl c 3 l 1 r 1 pwm r 12 v cc ( 5 v ) r 6 r 2 gnd r 11 vout up to 70 v 20 wleds per channel flt flt 2 . 2 f 10 k pgnd 10 f / 25 v x 3 p c s 2 . 2 f / 100 v x 6 p c s 1 f 75 k 50 m 787 k 10 k 25 . 5 k 20 k 10 k r 5 , 40 . 2 k 250 k d 1 10 k aon 6482 d f ls 1100 pad v in 3 . 3 h r cs figure 3 li-ion powered display application circuit example, 10 led @ 40ma v in ( 3 - 4 . 2 v ) s c 5014 a vcc en uvlo scp r e f f s e t scl sda i s e t pwm io 2 io 2 io 1 io 1 ovp c s p g n d n d r v r 4 r 3 c 6 q 1 c 12 sda r 8 r 15 c 1 scl c 3 l 1 r 1 pwm r 12 v cc ( 5 v ) r 6 r 2 gnd r 11 vout 5 wleds per stringl flt flt 2 . 2 f / 10 v 10 k pgnd 10 f / 6 . 3 v x 2 p c s 1 f 13 k 100 m 249 k 10 k 127 k 20 k 10 k r 5 , 60 . 4 k 100 k d 1 10 k si 2318 b 140 pad r cs
SC5014A 2 v in ( 6 - 27 v ) s c 5014 a vcc en uvlo scp r e f f s e t scl sda i s e t pwm io 2 io 2 io 1 io 1 ovp c s p g n d n d r v r 4 r 3 q 1 c 12 sda r 8 r 15 c 1 scl c 3 l 1 r 1 pwm r 12 v cc ( 5 v ) r 6 r 2 gnd r 11 vout flt flt 2 . 2 f pgnd 1 f 20 k 10 k r 5 pad d 1 c 6 l 2 c 8 r cs figure 4 sepic confguration v in ( 12 - 19 v ) s c 5014 a vcc en uvlo scp r e f f s e t scl sda i s e t pwm io 2 io 2 io 1 io 1 ovp c s p g n d n d r v r 4 r 3 c 6 q 1 c 12 sda r 8 r 15 c 1 scl c 3 l 1 r 1 pwm r 12 v cc ( 5 v ) r 6 r 2 gnd r 11 vout up to 70 v 20 wleds per channel flt flt 2 . 2 f 10 k pgnd 10 f / 25 v x 3 p c s 2 . 2 f / 100 v x 6 p c s 1 f 75 k 50 m 787 k 10 k 25 . 5 k 20 k 10 k r 5 , 40 . 2 k 250 k d 1 10 k aon 6482 d f ls 1100 pad v in 3 . 3 h r cs figure 5 cascode confguration drives 40 leds@200ma
SC5014A 22 acknowledgesfandfthefmasterfterminatesftheftransferfwithf thefstopfconditionf[p]. (2) combined format read afterfthefstartfconditionf[s],fthefslavefaddressfisfsent,ffol - lowedfbyfanfeighthfbitfindicatingfafwrite.ffthefsc50 4afi 2 cf thenfacknowledgesfthatfitfisfbeingfaddressed,fandfthef masterfrespondsfwithfanf8-bitfdatafbytefconsistingfoffthef registerfaddress.fthefslavefacknowledgesfandfthefmasterf sendsfthefrepeatedfstartfconditionf[sr].foncefagain,fthef slavefaddressfisfsent,ffollowedfbyfanfeighthfbitfindicatingf afread.fthefslavefrespondsfwithfanfacknowledgefandfthef 8-bitfdataffromfthefpreviouslyfaddressedfregister;fthef masterfthenfsendsfafnon-acknowledgef(nack).ffinally,fthef masterfterminatesftheftransferfwithfthefstopfconditionf[p]. (3) stop separated reads stop-separatedfreadsfcanfalsofbefused.fthisfformatfallowsf afmasterftofsetfupfthefregisterfaddressfpointerfforfafreadf andfreturnftofthatfslavefatfaflaterftimeftofreadfthefdata.finf thisfformatfthefslavefaddressffollowedfbyfafwritefcommandf aref sentf afterf af startf [s]f condition.fthef sc50 4af thenf acknowledgesf itf isf beingf addressed,f andf thef masterf respondsfwithfthef8-bitfregisterfaddress.fthefmasterfsendsf afstopforfrestartfconditionfandfmayfthenfaddressfanotherf slave.fafterfperformingfotherftasks,fthefmasterfcanfsendfaf startf orf restartf conditionf tof thef sc50 4af withf af readf command.fthefdevicefacknowledgesfthisfrequestfandf returnsf thef dataf fromf thef registerf locationf thatf hadfffffffff previouslyfbeenfsetfup. serial interface the i 2 c general specifcation thefsc50 4afisfafread-writefslave-modefi 2 cfdevicefandf compliesfwithfthefnxpfb.v.fi 2 cfstandardfversionf2. ,fdatedf januaryf2000.fthefsc50 4afhasf fuser-accessiblefinternalf 8-bitfregisters.fthefi 2 cfinterfacefhasfbeenfdesignedfforf programfflexibility,fsupportingfdirectfformatfforfwritef operation.freadfoperationsfarefsupportedfonfbothfcom - binedfformatfandfstopfseparatedfformat.fwhileftherefisfnof autofincrement/decrementfcapabilityfinfthefsc50 4afi 2 cf logic,faftightfsoftwarefloopfcanfbefdesignedftofrandomlyf accessfthefnextfregisterfindependentfoffwhichfregisterf youfbeginfaccessing.fthefstartfandfstopfcommandsfframef thefdata-packetfandfthefrepeatfstartfconditionfisfallowedf iffnecessary. limitations to the i 2 c specifcations thefsc50 4afonlyfrecognizesf7-bitfaddressing.fthisfmeansf thatf 0-bitfaddressingfandfcbusfcommunicationfarefnotf compatible.f thefdevicefcanfoperatefinfeitherfstandardf modef( 00kbit/s)forffastfmodef(400kbit/s). slave address assignment thef7-bitfslavefaddressfisf0 0 f x.fthefeighthfbitfisfthef datafdirectionfbit.f0x5ffisfusedfforfreadfoperationfandf 0x5efisfusedfforfwritefoperation. supported formats thefsupportedfformatsfarefdescribedfinftheffollowingf subsections. (1) direct format write thefsimplestfformatfforfanfi 2 cfwritefisfdirectfformat.ffafterf thefstartfconditionf[s],fthefslavefaddressfisfsent,ffollowedf byfanfeighthfbitfindicatingfafwrite.fthefsc50 4afi 2 cfthenf acknowledgesfthatfitfisfbeingfaddressed,fandfthefmasterf respon dsfwithfanf8-bitfdatafbytefconsistingfoffthefregisterf address.fthefslavefacknowledgesfandfthefmasterfsendsf thefappropriatef8-bitf datafbyte.foncefagain,fthefslavef
SC5014A 23 i 2 c direct format write s la ve a d d re ss r e g iste r a d d re ss d a ta s w a a a p s ? start c ondition w ? w rite = ? 0 ? a ? acknow ledge ( sent by slave ) p ? stop condition slave address ? 7 - bit r egister address ? 8 - bit d ata ? 8 - bit i 2 c stop separated format read s la ve a d d re ss r e g iste r a d d re ss s la ve a d d re ss b d a ta n a c k s w a a s / s r r a p p s la ve a d d re ss s r e g iste r a d d re ss s e tu p a cce ss m a ste r a d d re sse s o th e r s la ve s r e g iste r r e a d a cce ss s ? start c ondition w ? w rite = ? 0 ? r ? r ead = ? 1 ? a ? acknow ledge ( sent by slave ) n ak ? n on - acknow ledge ( sent by m aster ) sr ? r epeated start condition p ? stop condition slave address ? 7 - bit r egister address ? 8 - bit d ata ? 8 - bit i 2 c combined format read s la ve a d d re ss r e g iste r a d d re ss s la ve a d d re ss d a ta n a c k s w a a s r r a p s ? start c ondition w ? w rite = ? 0 ? r ? r ead = ? 1 ? a ? acknow ledge ( sent by slave ) n ak ? n on - acknow ledge ( sent by m aster ) sr ? r epeated start condition p ? stop condition slave address ? 7 - bit r egister address ? 8 - bit d ata ? 8 - bit
SC5014A 24 defnition of registers and bits fault status register bit field defnition read / write description 0x00f[7] clf w clearflatchingffagsfbit.f f (setf=f ftofclearfotp,fled_open,fled_shortfandfmaskfovpfforf32ftof64s) 0x00f[5] led_short r oneforfmorefledfstringsffaultedfshorted 0x00f[4] led_open r oneforfmorefledfstringsffaultedfopen 0x00f[2] otp r thermalfshutdownf( f=fthermalfotpffault) 0x00f[] ovp r outputfover-voltageffaultf(f f=fovpf) 0x00f[0] fault r orfoffallffaultfconditionsf(0=fnoffault,f f=ffaultfcondition) analog dimming control register bit field defnition read / write description 0x02f[4:0] idacf[4:0] rf/fw 5-bitfanalogfdimmingfregisterffthefledfcurrentfcanfadjustedfinf32fstepsffromf0maftofmaxf valuefdeterminedfbyfr iset . register map address bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 reset value description 0x00 clf led_ short led_ open otp ovp fault 0x00 faultfstatus 0x02 idac4 idac3 idac2 idac idac0 0xf analogfdimmingf control
SC5014A 25 b xn b b b c a b d 1 e 1 e d /2 .001 m a x .002 - .039 n o m 0 .80 0 .02 (0 .20) 0 .90 c o n t r o l lin g d im e n s io n s a r e in m il lim e t e r s (a n g l e s in d e g r e e s ). c o p l a n a r it y a p p l ie s t o t h e e x p o s e d p a d a s w e ll a s t h e t e r m in a ls . n o t e s : 2. 1. 1 2 n e 1 .100 .106 .110 2 .55 2 .70 2 .80 p in 1 in d ic a t o r 4 .10 3 .90 4 .00 4 .10 3 .90 .157 .154 .161 .154 .161 a a a c a c (la s e r m a r k ) d e b a 1 a a 2 s e a t in g p la n e l xn e /2 in c h e s .020 b s c b .007 b bb a aa n d 1 e l e d .012 .100 d im a 1 a 2 a m in .000 - .031 0 .30 0 .18 .012 0 .25 .010 0 .50 2 .80 0 .30 2 .55 .004 .004 20 .016 .157 .106 .020 .110 0 .10 0 .10 20 0 .40 4 .00 2 .70 0 .50 b s c m il l im e t e r s m a x 0 .05 - 1 .00 d im e n s io n s m in 0 .00 - n o m (.0 08) .035 outline drawing mlpq-20 4x4
SC5014A 26 land pattern mlpq-20 4x4 d im e n s io n s k h g z x p (c ) c o m p a n y 's m a n u f a c t u r in g g u id e l in e s a r e m e t . 4 .80 .1 89 z y f a il u r e t o d o s o m a y c o m p r o m is e t h e t h e r m a l a n d /o r t h e r m a l v ia s in t h e l a n d p a t t e r n o f t h e e x p o s e d p a d s h a l l b e c o n n e c t e d t o a s y s t e m g r o u n d p l a n e . f u n c t io n a l p e r f o r m a n c e o f t h e d e v ic e . 2 . t h is l a n d p a t t e r n is f o r r e f e r e n c e p u r p o s e s o n l y . c o n s u l t y o u r m a n u f a c t u r in g g r o u p t o e n s u r e y o u r n o t e s : 1 . d im x y h k p c g m il lim e t e r s in c h e s (3 .95) .0 10 .0 33 .1 22 .0 20 .1 06 .1 06 (.1 56) 0 .25 0 .85 2 .70 0 .50 2 .70 3 .10
semtechfcorporation powerfmanagementfproductsfdivision 200fflynnfroad,fcamarillo,fcaff930 2 phone:ff(805)f498-2 ffffax:ff(805)f498-3804 www.semtech.com contact information SC5014A 27 ?fsemtechf20 2 allfrightsfreserved.freproductionfinfwholeforfinfpartfisfprohibitedfwithoutfthefpriorfwrittenfconsentfoffthefcopyrightf owner.fthefinformationfpresentedfinfthisfdocumentfdoesfnotfformfpartfoffanyfquotationforfcontract,fisfbelievedftofbef accuratefandfreliablefandfmayfbefchangedfwithoutfnotice.fnofliabilityfwillfbefacceptedfbyfthefpublisherfforfanyfconse - quencefoffitsfuse.fpublicationfthereoffdoesfnotfconveyfnorfimplyfanyflicensefunderfpatentforfotherfindustrialforfintellec - tualfpropertyfrights.fsemtechfassumesfnofresponsibilityforfliabilityfwhatsoeverfforfanyffailureforfunexpectedfoperationf resultingffromfmisuse,fneglectfimproperfinstallation,frepairforfimproperfhandlingforfunusualfphysicalforfelectricalfstressf including,fbutfnotflimitedfto,fexposureftofparametersfbeyondfthefspecifedfmaximumfratingsforfoperationfoutsidefthef specifedfrange. semtechfproductsfarefnotfdesigned,fintended,fauthorizedforfwarrantedftofbefsuitablefforfusefinflife- supportfapplications,fdevicesforfsystemsforfotherfcriticalfapplications.finclusionfoffsemtechfproductsf infsuchfapplicationsfisfunderstoodftofbefundertakenfsolelyfatfthefcustomersfownfrisk.fshouldfafcustomerf purchaseforfusefsemtechfproductsfforfanyfsuchfunauthorizedfapplication,fthefcustomerfshallfindemnifyfandfholdf semtechfandfitsfofcers,femployees,fsubsidiaries,fafliates,fandfdistributorsfharmlessfagainstfallfclaims,fcostsfdamagesf andfattorneyffeesfwhichfcouldfarise. notice:fallfreferencedfbrands,fproductfnames,fservicefnamesfandftrademarksfarefthefpropertyfofftheirfrespectivef owners.

▲Up To Search▲

Price & Availability of SC5014A

	To Download SC5014A Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .