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high efciency integrated driver for 4-strings of 150ma leds sc441d power management revisionf2.0 features widefinputfvoltagefrangeffromf4.5vftof27v 42vfmaximumfoutputfvoltage drivesfupftof40fwledsfinf4fstringsf programmable led current for up to 150ma per string +/- 2% string-to-string current matching up to 90% efciency widef0.2%ftof 00%fpwmfdimmingfrange possiblefanalogfdimming integratedf3.0afpowerfswitch 700khzfswitchingffrequencyfforfsmallfsizeff adjustablefovpfforfcost-efectivefoutputfcapfselection open/short led protection short led protection disable thermalfprotectionfwithfauto-recovery thermallyfenhancedftssop-20fedpfpackage lead-free,fhalogen-freefandfweee/rohsfcompliant ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? description thefsc44 dfisfafhigh-efciencyfmultiplefstringfwledfdriv - erfwithfanfintegratedfboostfconverter.ffitfoperatesfoverfaf widefinputfrangeffromf4.5vftof27vfwithfafmaximumfout - putf voltagefoff 42vf andf af3.0af internalf powerfswitch.f f itf canfdrivefupftoffortyfwledsfinf4fstringsfwithfcurrentfupf tof 50mafperfstring.fffthefstring-to-stringfcurrentfmatch - ingfisf2%ftypical,f3%fmaximum.ffthefoverallfefciencyfisf greaterf thanf 90%f duef tof thef lowf currentf sensef voltagef andf af low-impedancef internalf powerf switch.f thef widef pwmfdimmingfrangefboastsfafratiofoff500:f . thef700khzfswitchingffrequencyfenablesfthefuserftofop - timizefthefexternalfcomponentfsizesfforfefciency.ffwhenf therefareffewerfthanf 0fledsfinfeachfstring,fusersfcanfad - justfthefoutputfvoltagefprotectionfyieldingfanfallowablef reductionfinfassociatedfcosts,fsizefandfvoltagefratingsfoff thefoutputfcapacitor. thef sc44 df alsof featuresf comprehensivef openf andf short-circuitfledfprotectionffunctions.fitfdisablesfthefcor - respondingfstringsfwithfledfopenforfledfshortfconditionsf whilefmaintainingfnormalfoperationfoffother,funafectedf ledfstrings.ffthisffeaturefallowsflcdfpanelsftofremainfview - ablefevenfunderfledffailure,fwirefdisconnect,forfshort-cir - cuitf conditions.fthef internalf thermalf shutdownf protectsf theficffromfoverheatingfatfabnormalfconditions. thefsc44 dfisfavailablefinfafthermally-enhancedftssop- 20fedpfpackage. typical application circuit 1 4 vout ss pgnd ioset io1-4 comp ovpin agnd vin sw pwm en sw fflag pgnd iognd sc441d 4 strings 1 12 vin (4.5v -27v) 2 edp pgnd ioset io1- 4 comp ss agnd vout ovpin scp_en applications medium-sizedflcdfpanel notebookfdisplay automotivefcarfnavigationfdisplay sub-notebookfandftabletfcomputerfdisplays portablefmediafplayers ? ? ? ? ?
sc441d 2 pin confguration ordering information marking information notes: ( )favailablefinftapefandfreelfonly.ffafreelfcontainsf2,500fdevices. (2)f availablefinflead-freefpackagefonly.ffdevicefisfweee/rohsf compliantfandfhalogen-free. ffffffffff(tssop-20fedp) ja = 39o c/w device package sc44 dtetrtf (1,2) tssop-20fedp sc44 devb evaluationfboard 5 5 4 4 3 3 2 2 1 1 d d c c b b a a vout io2 vin 10 fflag 20 iognd 11 comp agnd 1 ss sw en ovpin io3 sw io1 pgnd pgnd scp_en io4 pwm ioset sc44 df:fpartfnumber yywwf=fdatef(example:f 252) xxxxxxf=fsemtechflot#f(example:fa94a0 )
sc441d 3 recommended operating conditions absolute maximum ratings exceedingfthefabovefspecifcationsfmayfresultfinfpermanentfdamageftofthefdeviceforfdevicefmalfunction.ffoperationfoutsidefoffthefparametersf specifedfinfthefelectricalfcharacteristicsfsectionfisfnotfrecommended. notes- ( )fcalculatedffromfpackagefinfstillfair,fmountedftof3fxf4.5,f4flayerffr4fpcbfwithfthermalfviasfunderfthefexposedfpadfperfjesd5 fstandards. (2)ftestedfaccordingftofjedecfstandardfjesd22-a 4-b. electrical characteristics thermal information v in fpin:ffsupplyfvoltagefff-0.3ftof30v maximumfoutputfpowerfffffff22w sw,fovpin,,fvout,fio ~io4fvoltageffffffff-0.3ftof45vff iosetfvoltageffff-0.3ftof2v ss,fcompfvoltageffffff-0.3ftof4vff en,fpwm,ffflagfvoltageffff-0.3ftofv in f+0.3v pgndftofagndfffffffff0.3v peakfirfrefowftemperaturefff260c esdfprotectionflevel (2)ff ffffffff2.5kv inputfvoltagefrangeffff4.5v~27v outputfvoltagefffupftoff42v ledfcurrentffffupftof 50ma junctionftofambient () fffff39c/w maximumfjunctionftemperatureff 50c storageftemperaturefffff-65ftof+ 50c leadftemperaturef(soldering)f 0fsecffff260c unlessfotherwisefspecifed:fv in f= 2v,f-40cf sc441d 4 electrical characteristics (continued) parameter symbol conditions min typ max units compensation sourcingfcurrent i ea_source v comp f=f0.5v 5 a sinkingfcurrent i ea_sink v comp f=f2v 6 a control signals en,fpwm,fscp_enfhighfvoltage v en_h,f v pwm_h 2 v en,fpwm,fscp_enflowfvoltage v en_l,f v pwm_l 0.4 v en,fpwmfleakagefcurrent i en,f i pwmfff v en ,fv pwm f=f5v 0. a pwmfdimmingffrequency () f dimming 50 50k hz pwmfdimmingfminimumfdutyfcycle d min_dimming f dimming f=f200hz 0.2 % pwmfdimmingfminimumfpulse-widthf (2) t min_dimming 5 s pwmfdimmingfminimumfofftime t min_of 200 300 ns fflagfvoltage v fflag i fflag f=f2fma 0.25 v ssfsourcefcurrent i ss_source v ss f=f0v 4.5 a ssfsinkfcurrent i ss_sink v ss f=f2vfatfovpforfotp ssfswitchingfthreshold v ss_switching v in f=f 2v,ft j f=f25fc 0.5 0.7 .2 v ssfendfvalue v ss_end v in f=f2v 2.5 f v over-voltage protection ovpinfthreshold v ovpin_th ovpinf-fagnd .46 .52 .58 v ovpinfleakagefcurrent i ovpin v ovpin f=f20v 0. a voutfinternalfpull-downfcurrentfsource i ovp v out f=fv in f+f3v 0.9 ma voutfleakagefcurrent i vout_leak v out f=f40v 0. a current source (io1 ~ io4) currentfaccuracy i o ~i o4 t j f=f25fc 40 50 60 ma currentfmatching t j f=f25fc +/-f2 +/-3 % maximumfledfcurrent i omax 200 ma ledfshort-circuitfprotectionfthreshold v io_scp t j f=f25fc v leakagefcurrent i io_leak enf=f0,fv io f~fv io4 f=fv in 0. a
sc441d 5 parameter symbol conditions min typ max units overshootfprotectionfthreshold vi o ~vi o4 t j f=f25fc,fv io f~fv io4 0.963 .07 .77 v 0.9095 .07 .2305 v overshootfprotectionfhysteresis anyfoffi o ~i o4 00 mv led short circuit protection scpsetfcurrent i scpset 4 5 6 a max.fscpsetfthresholdfvoltage v scpset_max v inf - v over-temperature protection thermalfshutdownftemperature t otp 50 c thermalfshutdownfhysteresis t otp_h 30 c notes: ( )ffguaranteedfbyfdesign. (2)ffforfachievablefpwmfdimmingfminimumfpulse-widthfinfapplications,fseefthefcorrespondingfcurvesfinftypicalfcharacteristics.
sc441d 6 typical characteristics temperaturef( o c) uvlofthresholdfvs.ftemperature temperaturef( o c) uvlofhysteresisfvs.ftemperature vinfquiescentfsupplyfcurrent fvs.ftemperature temperaturef( o c) temperaturef( o c) compfsinkf/fsourcefcurrentf vs.ftemperature temperaturef( o c) ssfsinkf/fsourcefcurrentf vs.ftemperature swfsaturationfvoltagefatf af vs.ftemperature temperaturef( o c) voutfpullfdownfcurrentfsourcef vs.ftemperature temperaturef( o c) temperaturef( o c) fflagfsaturationfvoltagefvs.f temperature averagefledfcurrentfsourcefsetting vs.ftemperature temperaturef( o c) uvlo threshold vs. temperature temperature ( : ) vin uvlo (v) ??? ?? ??? ?? ??? ?? ?? ? ?? ?a3?????3 3?? vinfuvlof(v) uvlo hysteresis vs. temperature temperature ( : ) vin hysteresis (mv) ? ??? ??? ?? ?? ?? ?? ? ?? ?a3???3 3?? uvlofhysteresisf(mv) vin quiescent supply current vs. temperature temperature ( : ) vin quiescent supply current (mv) ?? ?? ?? ?? ? ? ? ?? ?? ? ?? ????3??3??3 3?? vinfquiescentfsupplyfcurrentf(ma) ? ? ? ? ?? ?? ? ?? ?3??at3??3 3?? comp sink/source current vs. temperature temperature ( : ) sink source current (ua) vin=12v ? ? ? ? ? ?? ? ?? ??3??at3??3 3?? ss sink/source current vs. temperature temperature ( : ) sink source current (ua) vin=12v ??? ??? ??? ??? ??? ?? ?? ?? ?? ? ?? ?3??3???3 3?? sw saturation voltage at 1a vs. temperature temperature ( : ) 4.5vin 12vin 27vin sw saturation voltage at 1a (mv) ?? ?? ?? ?? ? ??? ?? ? ?? 3??
3??3 3?? vout pull down current source vs. temperature temperature ( : ) 4.5vin 12vin 21vin vout pull down current source (ma) vout=vin+3v ? ? ??? ?? ??? ?? ??? ?? ? ?? ??3??3 ???3 3?? fflag saturation voltage vs temperature i fflag =2ma ovp threshold voltage (v) temperature ( : ) swfsaturationfvoltagefatf af(mv) voutfpullfdownfcurrentfsourcef(ma) fflagfsaturationfvoltagef(mv) ??? ??? ??? ?? ??? ?? ?? ?? ? ?? ? ?? ??3??3?3 3?? led current source setting vs. temperature temperature ( : ) vin=12v r ioset =1.74k ? led current source setting (ma) ledfcurrentfsourcefsettingf(ma) compfcurrentf(ua) ssfcurrentf(ua)
sc441d 7 typical characteristics (continued) temperaturef( o c) efciencyf(fp boost_output f/fp input ) boostfsectionfoutputfcurrentf(ma) ledfcurrentf(ma) ledfcurrentfsourcefsaturationfvoltagef vs.fledfcurrent ovpinfthresholdfvoltage fvs.ftemperature pwmfdimmingfminimumfpulsefwidthf vs.fpwmfdimmingffrequency pwmfdimmingfminimumfpulsefwidthf vs.fpwmfdimmingffrequency pwmfdimmingffrequencyf(khz) condition:fvinf=f 2v,fvoutf=f26.7vf/f0mafxf4f stringsf pwmfdimmingfminimumfdutyfcyclef vs.fpwmfdimmingffrequency pwmfdimmingffrequencyf(khz) vinf=f2v ? ??? ??? ??? ??? ?? ?? ?? ??? ?? ? ?? ?? ? ?? ??? ??? ??? ?? ??3??3 ???3 3?? led current source saturation voltage vs led curren t led current (ma) t a =25 : :: : led current source saturation voltage (mv) ledfcurrentfsourcefsaturationfvoltagef(mv) ???? ??? ??? ??? ??? ??? ??? ?? ?? ? ?? a?3????3 ???3 3?? ovpin threshold voltage vs temperature ovp threshold voltage (v) temperature ( : ) vin=12v ?? ?? ?? ? ?? ? ? ? ?? ?? ??? ??? ??? ??? ? ?? ???? efficiency 5vin 12vin 21vin pwmfdimmingfminimumfdutyfcyclef vs.fpwmfdimmingffrequency pwmfdimmingffrequencyf(khz) condition:fvinf=f 2v,fvoutf=f26.7vf/f0mafxf4f stringsf pwmfdimmingffrequencyf(khz) condition:fvinf=f 2v,fvoutf=f32vf/f50mafxf4f stringsf minimum pulse width vs frequency ? ? ? ?? ?? ?? ? ?? ?? ? ?? ?? ? ??? ??? ??? ??? ?? ???3?3?? ?3???3?t? ? ???3?3 3???????? pwmfdimmingfminimumfpulsefwidthf(us) minimum pulse width vs frequency ? ? ? ? ?? ?? ?? ?? ?? ? ?? ?? ? ??? ??? ??? ??? ?? ???3?3?? ?3???3?t? ? ???3?3 3???????? minimum duty cycle vs frequency ? ? ? ?? ? ?? ?? ?? ?? ?? ? ?? ?? ? ??? ??? ??? ??? ?? 3????3??? ?3???3?t? ? 3????3 3???????? minimum duty cycle vs frequency ? ? ? ? ? ?? ?? ? ?? ?? ? ??? ??? ??? ??? ?? 3????3??? ?3???3?t? ? 3????3 3???????? pwmfdimmingfminimumfpulsefwidthf(us) pwmfdimmingfminimumfdutyfcyclef(%) pwmfdimmingfminimumfdutyfcyclef(%) condition:fvinf=f 2v,fvoutf=f32vf/f50mafxf4f stringsf ovpinfthresholdfvoltagef(v) efciencyf(%) 0s4p
sc441d 8 typical characteristics (continued) voutf ( 0v/div) vswf (20v/div) vin ( 0v/div) vssf (2v/div) startfup timef(20ms/div) conditions:fvinf=f 2v,f outputf=f32vf/f 50mafxf4fledfstrings f conditions:fvinf=f 2v,f outputf=f32vf/f 50mafxf4fledfstringsf timef(400ms/div) shutfdown conditions:fvinf=f 2v,f outputf=f27vf/f20mafxf4fledfstringsf voutf accoupling (200mv/div) vsw (20v/div) timef( us/div) mainfpowerfswitchingfwaveform timef( us/div) mainfpowerfswitchingfwaveform conditions:fvinf=f 2v,f outputf=f32vf/f 50mafxf4fledfstrings start up sw ss vout vin testing condition: vin=12v, 25 : :: : , leds=10s4p@150/ch, 32vout shut down sw ss vout vin testing condition: vin=12v, 25 : :: : , leds=10s4p@150/ch, 32vout voutf ( 0v/div) vswf (20v/div) vin ( 0v/div) vssf (2v/div) testing condition: vin=12v, 25 : :: : , leds=10s4p@150/ch, 32vout main power switching waveform sw vout testing condition: vin=12v, 25 : :: : , leds=10s4p@20/ch, 27.4vout main power switching waveform sw vout voutf accoupling (50mv/div) vsw ( 0v/div)
sc441d 9 typical characteristics (continued) otp and otp recovery sw ss vout vin testing condition: vin=12v, 25 : :: : , leds=10s4p@150/ch, 32vout voutf (20v/div) vswf (20v/div) vin=2v vssf (2v/div) otpfandfotpfrecovery timef(40ms/div) conditions:fvinf=f 2v,f outputf=f32vf/f 50mafxf4fledfstrings f conditions:fvinf=f 2v,fio fhasfonefledfshortfcircuit, outputf=f32vf/f 50mafxf4fledfstringsf timef( 0ms/div) ledfshortfcircuitfprotection conditions:fvinf=f 2v,f outputf=f32vf/f 50mafxf4fledfstringsf timef(20ms/div) ledfopenfcircuitfprotection timef(2ms/div) pwmfdimming conditions:fvinf=f 2v,fio fledfstringfisfopenfcircuit, outputf=f32vf/f 50mafxf3fledfstrings voutf (20v/div) io2f ( v/div) vin ( 0v/div) iof (2v/div) led short circuit protection io_2 io_1 vout vin testing condition: vin=12v, 25 : :: : , leds=10s4p@150/ch, 32vout, io1 short led open circuit protection io_2 io_1 vout vin testing condition: vin=12v, 25 : :: : , leds=10s4p@150/ch, 32vout, io1 open voutf (20v/div) io2f ( 0v/div) vin (5v/div) iof (2v/div) pwm (5v/div) iof (5v/div) vin=2v swf (20v/div) pwm dimming sw pwm io1 vin testing condition: vin=12v, 25 : :: : , leds=10s4p@150/ch, 32vout, io1 open, dimming 200hz, 50% duty
sc441d 0 pin descriptions pin # pin name pin function io2 providesfconstantfcurrentfsourceftofledfstringf2. 2 io providesfconstantfcurrentfsourceftofledfstringf . 3 iognd constantfcurrentfsourcefground. 4 agnd analogfground 5 ss soft-startfpin 6 comp thefoutputfoffthefinternalftrans-conductanceferrorfamplifer.f 7 en enablefthefdevicefincludingfregulatorfandfledfdrivers. 8 ioset currentfsourcefiofvaluefsetfpin.ffbyfselectingfthefresistorfconnectedffromfthisfpinftofgnd,f thefcorrespondingfmaximumfcurrentfonfallf4fstringsfarefset. 9 pwm pwmfdimmingfcontrolfpinfforfledfstrings. 0 vout internalfpullfdownfcurrentfsourcefinfoverfvoltageffault.ffconnectfthisfpinfdirectlyftofboostfoutput. fflag powerffailurefsignalfoutputfwithfopenfcollector.fheldflowfunderfnormalfoperation. 2 vin powerfinputfvoltagefpin.fbypassedfwithfcapacitorsfcloseftofthefpin. 3 scp_en ofledfshort-circuitfprotectionfpinfCfleavingfthisfpinfopenfenablesftheffunction,ftyingfitftofgroundf disablesfit.ffiffanyfiofpinfconnectsftofvin,fscp_enfneedsftofbefleftfopenftofactivatefthefprotection. 4 ovpin over-voltagefprotectionfsensefsignalfinput. 5,8 pgnd powerfground 6,7 sw collectorfoffthefinternalfpowerfswitch.f 9 io4 providesfconstantfcurrentfsourceftofledfstringf4.ffconnectftofvinfforf3fstringsfoperation. 20 io3 providesfconstantfcurrentfsourceftofledfstringf3. edp solderftofthefgroundfplanefoffthefpcb. en status 0 backlightfdisable backlightfenable note:ffwhenfenf=f0;fthefboostfisfturnedfofffandfdisabled. note:ffanyfunusedfiofpinfshouldfbefpulledfupftofvin.
sc441d block diagram figure 1. sc441d block diagram 5 5 4 4 3 3 2 2 1 1 d d c c b b a a fault-1 tsd hiccup ovp uvlo hiccup hiccup fault ss 3v3 fault control logic vout disable1 en pwm vin sw agnd comp osc isense bandgap io1 scp_en ilim pgnd ss one io channel shown ioset fflag hiccup iognd uvlo & tsd pgnd led open/short/overshoot circuit protection current source ovpin sw led current setting ovp detect disable2 1v 4.5ua 4.5ua 0.9ma 0.9ma - + - + - + - + 1ua 1ua - + - + - + - + s r q
sc441d 2 applications information sc441d detailed description thef sc44 df containsf af highf frequency,f current-modef boostfregulatorfandffourfprogrammablefcurrentfsources.ff thef ledf currentf sourcef valuef isf setf usingf anf externalf resistorf whilef thef pwmf controllerf maintainsf thef outputf voltagefatfaflevelfkeepingfthefcurrentfregulatedfthroughf thefleds.ffsincefthefsc44 dfreceivesffeedbackffromfallfoff thefledfcurrentfsources,fallfledfstringsfcanfbefturnedfonf atfanyfgivenftime.ffaftypicalfapplicationfwouldfusef3- 0f backlightfledsfforfeachfstring,fdrivenfupftof 50ma.ff operation thefsc44 dfcontrolsfthefboostfconverterfsetfpointfbasedf onf instantaneousf requirementsf off fourf currentf sources.ff therefore,f onlyf af singlef inductorf andf powerf switchf isf neededftofprovidefpowerftofthefentireflightingfsubsystem,f increasingf efciencyf andf reducingf partf count.f f af digitalf interfaceftofoutputfcontrolfisfhigh-bandwidth,fsupportingf digitalf pwmf dimmingf atf 50hzf tof 50khzf dimmingf frequency,fwhilefaggressivelyfshuttingfthefentirefsupplyf currentf downf tof 3maf (typical),f whenf allf ledf stringsf aref turnedfof.ff highf frequencyf switchingf providesf highf outputf powerf usingfaftinyf .0mmfhighfinductor,fmaximizingfefciencyf forf space-constrainedf andf cost-sensitivef applications.ff additionally,f bothf converterf andf outputf capacitorf aref protectedf fromf open-ledf conditionsf byf over-voltagef protection. led current programming thef sc44 df featuresf programmablef ledf currentf regulators.fthef ledf currentf setf pointsf aref chosenf usingf externalf resistorsf tiedf tof thef iosetf pin.fthef relationshipf betweenfthefprogrammingfresistorfvaluefandfthefoutputf currentfsetfpointfcanfbefdescribedfasffollows: r ioset f=f(0.26 v)f/fi led wherefr ioset ffisfinfk?.fi led fisfthefledfcurrentfinfamperes.f theffourfoutputfchannelsfhavefthefsamefoutputfcurrent. start-up duringf start-up,f whenf thef vinf pinf voltagef reachesf itsf uvloffthresholdfandfbothfthefenfandfpwmfsignalsfarefsetf tofhigh,fthefssfpinfbeginsftofsourcef4.5afasfitsfvoltagef beginsftofriseffromf0vftofitsfendfvaluefoff2.5v.fthefoutputf voltagefoffthefinternalftrans-conductanceferrorfampliferf (comp),fincreasesfandfclampsftofthefssfpinfvoltage.fwhenf thefssfpinfvoltagefreachesfitsfswitchingfthreshold,foutputf voltagef increases.f properf decouplingf isf requiredf onf thef vinfpin,fespeciallyfforfaflowerfinputfvoltagefcondition.faf 22f,f6.3vfratedfx5rfceramicfcapacitorfisfrecommendedf forfaf5vfinputfsystem. thef internalf ledf currentf sourcef (io f ~f io4)f helpsf tof regulatefthefledfcurrentftofitsfsetfpointfwhilefthefoutputf voltagefincreases;fafsuitablefamountfofferrorfinformationf willfbefgeneratedfonfthefinternalferrorfamplifer.fthefcompf pinfvoltagefkeepsfrisingfandfoncefthefledfcurrentfreachesf itsfsetfpoint,ftheferrorfinformationfwillfnotfbefgeneratedf byfthefledfcurrentfsource.ffthefcompfpinfvoltagefstaysf levelfwhilefkeepingfthefledfcurrentfinfitsfsetfpoint. iffthefenfpinfvoltagefisfpulledfbelowf0.4v,fthefsc44 dfwillf stayfinfshutdownfmodeffdrawingflessfthanf affromfitsf inputfpowerfsupply. duringf thef normalf operation,f whenf pwmf pinf isf pulledf belowf 0.4v,f thef devicef operatesf inf standbyf mode,f drawingf3maf(typical)fcurrentffromfthefinput.funderfthisf condition,f sincef thef enf pinf isf pulledf high,f soft-startf isf initiatedfandfthefssfpinfvoltagefisfraisedftofitsfendfvalue.ff followingfthis,fwhenfthefpwmfsignalfgoesfhighftofenablef thefsc44 d,fthefcompfpinfvoltagefwillfrisefquicklyfsincef itfisfnotflimitedfbyfthefssfpin.fafproperfcapacitancef( 0nff ~f 00nf)fisfrequiredftofpreventfoutputfvoltagefovershootf onfthefcompfpinfandfitsfexternalfrcfnetwork.f shut down iffthefvinfpinfvoltageffallsfbelowfitsfuvlo,forfthefvoltagef onfthefenfpinfgoesflow,fthefdevicefwillfrunfinfshutdownf modefasfthefinternalfswitchfandfthefledfcurrentfsourcesf willfimmediatelyffturnfof.fthefssfcapacitorfisfdischargedf byfthefinternalfcurrentfsourcefoffthefssfpin.ffthefssfpinf voltagefdecreasesftof0vfwhilefthefoutputfvoltageffallsftof thefsameflevelfasfthefinputfvoltage. iff thef pwmf pinf voltagef goesf lowf whilef sc44 df isf inf normalf operation,f thenf thef sc44 df willf runf inf standbyf mode.fthefinternalfswitcherfandfthefledfcurrentfsourcef willfimmediatelyfturnfof.f noteC thefpwmfsignalfdoesfnotfafectfthefssfpinfnorfitsffnalfvalue.f main power operation sc44 dfisfaf700khzffxed-frequency,fpeakfcurrent-modef step-upf switchingf regulatorf withf anf integratedf 3.0af (minimum)fpowerftransistor.f
sc441d 3 applications information (continued) therefarefsomefchoices. )fleavefsomefroomfbetweenfvinfrangefandfvo. 2)foperatefthefboostfconverterfatfnormalfloadf(lessfro) 3)fincreasesfthefboostfinductancef(l). over-current protection sc44 df providesf cycle-by-cyclef currentf limitingf forf itsf internalf switch.f iff thef switchf currentf exceedsf 4. af (thef typicalf current-limitf tripf point),f thenf thef current-limitf comparatorfilim,fwillfsetftheflatchfimmediatelyfturningfoff internalfpower.ffallfledfcurrentfsourcesfkeepfoperatingfinf anfover-currentfcondition.ffdueftofseparatefpulse-widthf modulatingfandfcurrentflimitingfpaths,fthefocpftripfpointf isfnotfafectedfbyfslopefcompensationf(i.e.ftripfpointfisfnotf afectedfbyfswitchingfdutyfcycle). over-voltage protection (ovp) sc44 dfincludesfanfexternalfprogrammingfover-voltagef protectionfcircuitftofpreventfdamageftoftheficfandfoutputf capacitorfinfthefeventfoffanfopen-circuitfcondition.fftheff boostfconvertersfoutputfvoltagefisfdetectedfatfthefovpinf pin.fiffthefvoltagefatfthefovpinfpinfexceedsf .52vf(typical),f thefboostfconverterfwillfshutfdownfandfaf0.9mafpull-downf currentfwillfbefappliedftofthefvoutfpinftofquicklyfdischargef thef outputf capacitor.f fthisf addedf protectionf preventsf af conditionfwherefthefoutputfcapacitorfandfschottkyfdiodef mustf enduref highf voltagef forf anf extendedf time,f whichf canfposefafreliabilityfriskfforfthefusersfsystem.f referf tof evaluationf applicationf circuitf inf page 8.f thef outputfoverfvoltageftripfpointfcanfbefprogrammedfbyfr5f andfr7fresistorfdivider.f thefrelationshipfcanfbefdescribedfasffollows: wherefovpin_thfisf .52vftypical. anf ovpf eventf causingf af faultf couldf disablef thef boostf converterfenablingfthefdeviceftofafstrongfpull-down.ffthisf eventfwouldfcauseftheffflagfpinftofgofhighfandfthefsoft- startfcapacitorftofdischarge.ffwhenfthefsoft-startfcapacitorf voltagef fallsf belowf 0.5v,f andf thef outputf voltagef fallsf tof vin,fsc44 dfentersfafsoft-startfprocess.f thefovpfdetectionfcircuitryfprovidesfafdisconnectffunctionf duringfthefshutdownfstateftofpreventfanyfleakageffromf thef output.fthef externalf ovpf resistorf dividerf shouldf bef connectedfbetweenfvoutfandfovprtnfwithfthefcentralf referringftofthefblockfdiagram,ffiguref ,fthefclockffromfthef oscillationfsectionfresetsftheflatchfandfturnsfonfthefpowerf transistor.f switchf currentf isf sensedf withf anf integratedf sensef resistor.f thef sensedf currentf isf summedf withf thef slope-compensatingf rampf andf fedf intof thef modulatingf rampfinputfoffthefpwmfcomparator.ftheflatchfisfsetfandf thef powerf transistorf conductionf isf terminatedf whenf thef modulatingf rampf intersectsf withf thef errorf ampliferf outputf(comp).f thef current-modef switchingf regulatorf isf af dual-loopf feedbackf controlf system.f f inf thef innerf currentf loop,f thef eafoutputf(comp)fcontrolsfthefpeakfinductorfcurrent.finf thef outerf loop,f thef errorf ampliferf regulatesf thef outputf voltagef tof keepf thef ledf currentf atf settingf point.f thef doublefreactivefpolesfoffthefoutputflcfflterfarefreducedf tof af singlef realf polef byf thef innerf currentf loop,f allowingf thefsimplefloopfcompensationfnetworkftofaccommodatef afwidefrangefoffinputfandfoutputfvoltages. f itfisfwellfknownfthat,finfboostfconverter,fvofisfgreaterfthanf orfequalftofvin.finfnormalfcontinuousfconductionfmodef (ccm)foperation, d v v in o ? = 1 1 where,fdfisfthefdutyfratiofoffthefpwmfpowerfswitch.fasf vinfincreases,finforderftofregulatefvoftofafgivenfconstantf value,f df decreases.f whenf vinf approachesf vo,f df surelyf leadsf tof 0.f inf practice,f duef tof thef minimumf on-timef off thefpwmfpowerfswitch,fdfusuallyfcouldfnotfapproachf0f withf infnitelyf smallf granularity.f atf somef point,f itf eitherf producesfonefpulsefwithfminimumfon-timeforfgeneratesf 0fbyfskippingfthefpulse.fsuchfpointfcouldfbeftheoreticallyf calculatedfforfsc44 dfasffollows. forfccm:fffvinff0.92fvo. forfdcmf(discontinuousfconductionfmode):ff where,frofisfthefboostfequivalentfoutputfresistancef(=vo/ io),flfisfthefboostfinductorf(infuh). inf manyf boostf converterf designsf andf operations,f pulsef skippingf isf normallyf allowedf atf lightf loadf conditions.f somefdesignersfevenfpurposelyfletfthefboostfpowerfcon - verterfenterfthefpulsefskippingfinforderftofsavefpowerfatf lightfloadfconditions.fiffsomefdesignersfdofnotfwantfpulsef skippingfmode,fbasedfonfthefconditionsfprovidedfabove,f 2 7 7 5 _ _ r r r th ovpin trip ovp u o o in v l r v * 10 * 6 . 1 1 1 2 2 t
sc441d 4 applications information (continued) tapfconnectedftofovpin.f note:f f iff thisf disconnectf functionf isf notf desired,f bypassf thefovprtnfpinfandfconnectfthefendfoffthefovpfresistorf dividerf directlyf tof gnd.f thef ovpinf pinf isf sensitivef tof noise,fandfafproperfdecouplingfcapacitorf( nff~f 0nf)fisf required.fthefcombinedfimpedancefoffthefresistorfdividerf forfovpinfshouldfbefgreaterfthanf200k?. led short-circuit protection iff onef orf moref ledsf aref detectedf asf shortened,f thatf correspondingf stringf willf bef latchedf off iff scp_enf isf foating.fthefvoltagesfonfallfinternalfledfcurrentfsourcesf (iofpins)farefmonitoredftofseefiffanyfexceedsfthefsettingf voltagef(thefiofvoltagefonfabnormalfledfstringfwillfrisef earlierfthanfotherffoatingfledfstrings).fiffanyfiofpinfvoltagef exceedsfthefsettingfvoltage,fthatfiofcurrentfsourcefwillfbef latchedfof.ftheflatchfcanfbefresetfiffvinffallsfbelowfuvlof orfrecyclefenfsignal.fotherfnormalfledfstringsfremainfatf theirf normalf operation.f thef protectionf willf bef disabledf iffscp_enfisftiedftofgnd.fiffallfiofpinfvoltagesfreachf0.8vf thenfthefinternalfmainfswitchfwillfbefoffuntilfanyfoffthefiof voltagesfisflowerfthanf0.7v. thefsettingfvoltagefforfscpfcanfbefprogrammedfbyfr33f (seefthefschematicfonfpagef 8).fthefrelationshipfcanfbef describedfasffollows: ffffvscp(v)=0.05 fxfr 33 (k ? ) wherefvscpfisfthefscpfsettingfvoltagefinfvoltfandfr 33 fisfinf kohm. unused strings thef sc44 df mayf bef operatedf withf lessf thanf 4f strings.f infthisfcase,fallfunusedfstringsfshouldfbeftiedftofvinfandf leavefthefscp_enfpinffoating. led open-circuit protection iff anyf ledf stringf isf detectedf asf anf open-circuit,f thatf stringf willf latchf of.f iff anyf givenf stringf isf open,f thef iof currentfsourcefwillfgoftofdeepfsaturation;fthefcompfandf fflagf pinsf willf bef drivenf highf andf thef boostf converterf dutyf cyclef willf increasef causingf voutf tof rise.f f atf somef pointfvoutfwillfrisefhighfenoughftofcausefallfthefiofpinf voltagesf off thef intactf stringsf tof reachf thef shortedf ledf detectionflevelfandflatchfoffthosefstrings.ffbecausefoffthef ledfopenfstringfvoutfwillfcontinueftofrisefuntilfitfreachesf thefprogrammedfovpflevel.f whenf ovpf isf reached,f thef voltagef onf thef iof pinsf aref monitoredf andf iff anyf iof voltagef isf lessf thanf 0.2vf thatf stringfwillfbefidentifedfasfopenfandfwillflatchfof.ff onlyf whenf vinf fallsf belowf uvlo,f orf anf enf signalf isf re - cycled,fandfiffthermalfshutdownfoccurs,fcanfthisflatchfbef reset.f f af hiccupf cyclef isf thenf initiatedf andf thef ssf pinf isf dischargedfslowlyfwithfaf afcurrentfsourcefandfaf0.9maf dischargefpathf(turnedfonftofpullfdownfvout).ffwhenfssf fallsfbelowf0.5vfandfvoutffallsfbelowftofvin,fthefshortedf ledf detectionf latchesf aref resetf andf af newf soft-startf se - quencefisfinitiatedftofresumefnormalfoperation. thermal shutdown (tsd) iffthefthermalfshutdownftemperaturefoff 50 c fisfreached,f afhiccupfsequencefisfinitiatedfwherefthefboostfconverterf andfallfiofcurrentfsourcesfarefturnedfof.fffssfisfdischargedf byf af af currentf source,f andf af 0.9maf dischargef pathf isf turnedfonftofpullfdownfvout.ffasftemperatureffallsfbelowf theftsdftripfpoint,fsc44 dfwillfretryfwhenfssffallsfbelowf 0.5vfandfvoutffallsftofvin. pwm dimming thefpwmfinputfneedsftofbefheldfhighfforfnormalfoperation.ff pwmfdimmingfcanfbefdonefbyfcyclingfthefpwmfinputfatfaf givenffrequencyfwherefaflowfonfthefpwmfinputfturnsfoff allfiofcurrentfsourcesfandfafhighfturnsfonfallfiofcurrentf sources.ffthefshortfandfopenfdetectionflatchesfarefblankedf forfapproximatelyf2sfasfthefpwmfinputftransitionsffromf low-to-highftofpreventfaffalseffaultfdetectionfduringfpwmf dimming. thefpwmfpinfcanfbeftoggledfbyfexternalfcircuitryftofallowf pwmfdimming.ffinfaftypicalfapplication,fafmicrocontrollerf setsf af registerf Cf orf counter,f thatf variesf thef pulse-widthf onf af gpiof pin.f f thef sc44 df allowsf dimmingf overf twof decadesf inf frequencyf (50hzC50khz),f inf orderf tof allowf compatibilityfwithfafwidefrangefoffdevices,fincludingfthef newestf dimmingf strategiesf thatf avoidf thef audiof bandf byfusingfhighffrequencyfpwmfdimming.ffinfthisfmanner,f af widef rangef off illuminationf canf bef generatedf whilef keepingfthefinstantaneousfledfcurrentfatfitsfpeakfvaluef forfluminescentfefciencyfandfcolorfpurity.fffurthermore,f advancedflightingfefectsfsuchfasfbacklightfdim-onfcanfbef implementedfasfthefsc44 dfcanfresolvef 0sf(minimum),f pwmfdimmingfpulse-width. asf farf asf thef maximumf pwmf dimmingf pulse-width,f itf
sc441d 5 applications information (continued) dependsf onf thef pwmf dimmingf frequency.f clearly,f itf isf trivialf tof getf 00%f ledf brightnessf byf pullingf pwmf pinf highf constantly.f whenf thef userf triesf tof dimf thef ledf brightnessfusingfpwmfsignalffromf 00%fdown,fheforfshef needsftofobserveftheffollowing.fwhenfthefpwmfdimmingf signalf isf activelyf switchingf fromfhighf toflowf andf tof high,f theref isf af minimalf offf timef (t_of_min,f 200ns,f guaranteedfbyfdesign)frequirementfoffthefpwmfdimmingf signalf withf thisf ic.f f f f suchf minimalf offf timef setsf thef maximumfpwmfdutyfratiofbeforefhittingftof 00%finfthef followingfway. d max = -t of_min f pwm forf example,f iff thef pwmf dimmingf frequencyf f_ pwm=200hz,fthefd_max=99.996%.fifff_pwm=25khz,fthef d_max=99.5%.f withf mostf practicalf dimmingf interfaces,f thefneededfdimmingfstepsfandfresolutions,fitfisfuncommonf tofrunfintofthefabovefd_maxfbeforefreachingf 00%.fwhilef mostfapplicationsfwillfnotfrunfintofd_max,fthefdesignerf shouldfbefawarefoffpossiblefparasiticfelementsffromfpwmf dimmingf interfacef tof thef pwmf pinf off sc44 d.f usually,f simplyfcheckingfsignalfd_maxfatfpwmfpinfoffsc44 dfisf sufcient. linear dimming thef linearf dimmingf controlf isf availablef forf sc44 df byf applyingf anf externalf controlf voltagef onf iosetf pinf throughf anf externalf resistor-likef circuitf (shownf below).f externalfenvironmentfbrightnessfcompensationfcanfalsof befachievedfwhenfthefcontrolfvoltagefisfgeneratedfbyfaf lightfsensorfcircuit. ffffffffffffffffff 5 5 4 4 3 3 2 2 1 1 d d c c b b a a v_ext r_ext r_ioset ioset thefiosetfvoltagefisf0.5vfwhenflinearfdimmingfisfusedfandf thef minimumf iosetf currentf mustf bef higherf thanf 27af (i.e.f 5mafperfledfstring).fftheffexternalfcontrolfvoltagef slewfratefmustfslowfatf v/ 0ms. led strings connection generally,f ledf stringsf aref connectedf tof io f ~f io4f pinsf throughf af mechanicalf connectorf which,f generally,f can - notfsupportfanfelectricalfconnectionftherebyfresultingfinf signifcantf noise.f f consequently,f thef sc44 df ledf short- circuitf protectionf mayf falsef tripf whenf thef noisef levelf isf large.ffcertainfceramicfdecouplingfcapacitorfonfpinsfio f~f io4ftofgndfarefusefulftofpreventfthefsc44 dffromfnoisef infuence. asfafgeneralfguideline,fthefdecouplingfcapacitancefshouldf beflimitedfasffollows. o led dcple v us i c 6 . 0 * where,fi_ledfisfthefledfcurrentfperfstring,fvofisfthefboostf outputfvoltagefandfc_dcplefisfthefsuggestedfdecouplingf capacitorfvalue. forf example,f iff i_led= 0ma,f vo= 3.5v,f thef calculatedf upperf boundf off c_dcplef isf aboutf 444pf.f onef couldf usef 390pff orf lessf inf thef circuit.f f iff i_led= 00ma,fvo= 3.5v,f thef calculatedf upperf boundf off c_dcplef isf aboutf 4.44nf.f onefmayfusef3.9nfforflessfinfthefcircuit.ffinfsomefappli - cations,f circuitf designersf tendf tof selectf thef decouplingf capacitorsfinfthefrangefoff( 00pff~f nf).ffforfsomeflowf ledfcurrentf(e.g.f 0ma)fapplications,fitfisfrecommendedf tofaddf m- 0mohmfresistorffromfiofpinftofgndfinforderf tofreducefiofpinfvoltagefduringfpwmfdimming. parallel operation whenftwoforfmorefsc44 dsfarefoperatingfinfparallelfforf af large-sizedf panelf application,f audiblef noisef mayf bef observedf duef tof non-synchronousf switchingf frequency.f thefripplefvoltagefonfthefinputfvoltagefrailfwillfbefmod - ulatedf byf thef beatf frequencyf resultingf inf audiblef noise.f thisfsituationfcanfbefresolvedfbyfaddingfanfinputfinduc - torf betweenf inputf voltagef railf andf thef sc44 dfvinf pin.f thisfsituationfcanfalsofbefimprovedfbyfaddingfmorefinputf decouplingfcapacitors.f inductor selection thefinductancefvaluefoffthefinductorfafectsfthefconvert - ersf steadyf statef operation,f transientf response,f andf itsf loopfstability.fspecialfattentionfneedsftofbefpaidftofthreef specifcationsfoffthefinductor,fitsfvalue,fitsfdcfresistancef andf saturationf current.fthef inductorsf inductancef valuef alsofdeterminesfthefinductorfripplefcurrent.fthefconverterf canfoperatefinfeitherfccmforfdcmfdependingfonfitsfwork - ingfconditions.fthefinductorfdcfcurrentforfinputfcurrentf canfbefcalculatedfas,
sc441d 6 9 , 9 , ,1 28 7 28 7 ,1 ? ? i in f-finputfcurrent; ffffffffffi out fCfoutputfcurrent; ffffffffffv out fCfboostfoutputfvoltage; ffffffffffv in fCfinputfvoltage; fffffffffff fCfefciencyfoffthefboostfconverter. thenfthefdutyfratiofis, ' 28 7 ' ,1 28 7 9 9 9 9 9 ' v d f Cf forwardf conductionf dropf off thef outputf rectifyingf diode whenfthefboostfconverterfrunsfinfdcmf(flffl boundary .ffgenerallyf thef converterf hasf higherf efciencyf underf ccmf andf thef inductorfpeakfcurrentfis, / ) ' 9 , , 6 ,1 ,1 shdn / ? ? ? forfmanyfapplications,fanfinductorfwithfvaluefoff4.7hftof 22hfshouldfbeffne,fsuchfasfforftheftypicalfcasefshownf onfpagef .fthefinductorfpeakfcurrentfmustfbeflessfthanfitsf saturationfrating.fwhenfthefinductorfcurrentfisfcloseftofthef saturationflevel,fitsfinductancefcanfdecreasef20%ftof35%f fromfthef0afvaluefdependingfonfthefvendorfspecifcations.ff usingfafsmallfvaluefinductorfforcesfthefconverterfunderf dcmfinfwhichfcasefthefinductorfcurrentframpsfdownftof zerofbeforefthefendfoffeachfswitchingfcycle.fitfreducesfthef boostfconvertersfmaximumfoutputfcurrent,fandfproducesf largef inputf voltagef ripple.f anf inductorf withf largerf inductancef willf reducef thef bandwidthf off thef feedbackf loop,f possiblyf higherf dcf resistancef (dcr).f inductorsf dcrf playsf af signifcantf rolef forf thef totalf efciencyf sincef thefpowerftransistorfisfintegratedfinsidefthefsc44 d.foff course,ftherefisfaftrade-offbetweenfthefdcrfandfinductorf size.f f tablef 2f listsf recommendedf inductorsf andf theirf vendors. table 2. recommended inductors output capacitor selection thef nextf taskf inf sc44 df designf isf targetingf thef properf amountf off ripplef voltagef duef tof thef constant-currentf ledfloads.fftheftwoferrorfamplifersfthatfcontrolfthefpwmf converterf sensef thef deltaf betweenf requestedf currentf andfactualfcurrentfinfeachfoutputfcurrentfregulator.ffonf af cycle-by-cyclef basis,f af smallf amountf off outputf ripplef ensuresf goodf sensingf andf tightf regulation,f whilef thef outputfcurrentfregulatorsfkeepfeachfledfcurrentfatfaffxedf value.ffoverall,fthisfallowsfusagefoffsmallfoutputfcapsfwhilef ensuringf precisionf ledf currentf regulation.f althoughthef mechanicsfoffregulationfandffrequencyfdependencefmayf befcomplex,factualfselectionfoffoutputfcapacitorfcanfbef simplifedf becausef thisf capacitorf isf mainlyf selectedf forf thef outputf ripplef off thef converter.f assumef af ceramicf capacitorfisfused.fthefminimumfcapacitancefneededfforfaf givenffripplefcanfbefestimatedfby, ripple s out out n out out v f v i ) i v (v c ? ? x v ripple fCfpeakftofpeakfoutputfripple; ffffffffffi out fCfoutputfcurrent; ffffffffffv out fCfboostfoutputfvoltage; ffffffffffv in fCfinputfvoltage; fffffffffff s fCfswitchingffrequency. duringf loadf transient,f thef outputf capacitorf suppliesf orf absorbsf additionalf currentf beforef thef inductorf currentf reachesf itsf steadyf statef value.f largerf capacitancef helpsf withfthefovershootfandfundershootsfduringfloadftransient,f andf loopf stability.f recommendedf ceramicf capacitorf manufacturersfareflistedfinftablef3. inductor website dr74,f4.7hf~f5h www.cooperet.com ihlp-2525cz-0 ,f4.7f~f0h www.vishay.com ds85lc,f6.8hf~f 0h www.tokoam.com applications information (continued)
sc441d 7 table 3. recommended ceramic capacitor manufacturers vendor phone website kemet 408-986-0424 www.kemet.com murata 84-237-43 www.murata.com taiyofyuden 408-573-450 www.t-yuden.com output rectifying diode selection schottkyf diodesf aref thef idealf choicef forf sc44 df duef tof theirflowfforwardfvoltagefdropfandffastfswitchingfspeed.ff tablef4fshowsfseveralfdiferentfschottkyfdiodesfthatfworkf wellf withf thef sc44 d.f makef suref thatf thef diodef hasf af voltagefratingfgreaterfthatfthefpossiblefmaximumfouputf voltage.fthefdiodefconductsfcurrentfonlyfwhenfthefpowerf switchfisfturnedfof.fffafdiodefoff2affwillfbefsufcientfforf mostfdesigns. table 4. recommended rectifying diodes part vendor ss23 ss24 vishay www.vishay.com layout guidelines thef sc44 df containsf af boostf converterf andf thef place - mentsf off thef powerf componentsf outsidef thef sc44 df shouldf followf thef layoutf guidelinesf off af generalf boostf converter.fthefevaluationfapplicationfcircuitfonfpagef 8f willfbefusedfasfanfexample.ffc2fandfc3farefinputfdecou - plingfcapacitorfforfsc44 dfvinfpinfandfmainfpowerfinput.f c2,c3fshouldfbefplacedfasfclosefasfpossibleftofthefvinfpinf tofachievefthefbestfdecouplingfperformance.f tof minimizef thef switchingf noise,f thef switchingf loopf formedf byf inputf decouplingf capacitors,f internalf switch,f outputf schottkyf diodef andf outputf capacitorsf mustf bef minimized.f thef ledf currentf programmingf resistor(r6),f compensationfnetworkf(r9,c5,c7)fandfsoftfstartfcapacitorf (c6)fshouldfbefplacedfasfclosefasfpossibleftofsc44 d.fthef c4~c 7farefdecouplingfcapacitorsfforfledfcurrentfsourcef whichf preventf iof pinsf fromf noisef infuence.f c 4~c7f shouldfbefplacedfcloseftofeachfcorrespondingfiofpin. usef anf isolatedf localf agndf planef underneathf thef con - trollerfandftiefitftofthefnegativefsidefoffoutputfcapacitorf applications information (continued) throughfr 4fforfbetterfnoisefimmunity.
sc441d 8 evaluation application circuit f item reference quantity description package part vendor c,fc4,fc5, c6,fc7 5 50vfceramicfcapacitor,fx7r sm_0603 nf panasonic 2 c2 25vfceramicfcapacitor,fx5r sm_206 0uf panasonic 3 c8,fc9 2 50vfceramicfcapacitor,fx5r sm_206 4.7uf panasonic 4 c4 25vfceramicfcapacitor,fx5r sm_0805 2.2uf panasonic 5 c5 6.3vfceramicfcapacitor,fx7r sm_0603 47nf panasonic 6 c6 6.3vfceramicfcapacitor,fx7r sm_0603 00nf panasonic 7 d 60v,f2afschottkyfdiode sma b260 diodesforfany 8 l 6.8h,f3.67a dr74 6.8h copperforfany 9 r,fr8,fr4 3 %fsmdfresistor sm_0603 0r any 0 r2,fr3,fr4,fr7 4 5%fsmdfresistor sm_0603 0k any r5 %fsmdfresistor sm_0603 220k any 2 r6 %fsmdfresistor sm_0603 rioset any 3 r9 5%fsmdfresistor sm_0603 .5k any 4 r9,fr0,fr, r2,fr3 5 5%fsmdfresistor sm_0603 r any 6 r33 5%fsmdfresistor sm_0603 59k any 5 u controller edpftssop-20 sc44d semtech 5 5 4 4 3 3 2 2 1 1 d d c c b b a a pwm en io1 io2 io3 io4 vin vout vin vout vout l1 6.8uh l1 6.8uh c8 4.7uf/50v c8 4.7uf/50v c15 1nf c15 1nf r13 1r r13 1r c9 4.7uf/50v c9 4.7uf/50v r2 10k r2 10k c14 1nf c14 1nf r4 10k r4 10k c1 1nf c1 1nf r7 10k r7 10k c6 100nf c6 100nf r1 0r r1 0r c2 10uf/25v c2 10uf/25v r33 59k r33 59k r9 1.5k r9 1.5k c7 n.p. c7 n.p. r12 1r r12 1r r19 1r r19 1r d1 d1 c16 1nf c16 1nf r6 rioset r6 rioset r8 0r r8 0r c17 1nf c17 1nf r11 1r r11 1r r5 220k r5 220k c5 47n c5 47n u1 sc441d u1 sc441d io2 1 io1 2 iognd 3 agnd 4 ss 5 comp 6 en 7 ioset 8 pwm 9 vout 10 fflag 11 vin 12 scp_en 13 ovpin 14 pgnd 15 sw 16 sw 17 pgnd 18 io4 19 io3 20 edp 21 c3 n.p. c3 n.p. r14 0r r14 0r c4 2.2uf/25v c4 2.2uf/25v r10 1r r10 1r r3 10k r3 10k evaluation board bill of materials
sc441d 9 outline drawing - tssop-20 edp e a1 a2 a f h exposed pad bottom view f h .144 .112 .150 .118 .154 .122 3.66 2.85 3.81 3.00 3.91 3.10 inches b n ccc aaa bbb 01 e1 e l l1 e d c a2 a1 dim a min max millimeters min dimensions nom max nom e1 bbb c a-b d ccc c dimensions "e1" and "d" do not include mold flash, protrusions 3. or gate burrs. datums and to be determined at datum plane controlling dimensions are in millimeters (angles in degrees). -b- notes: 1. 2. -a- -h- side view (.039) .004 .008 - .024 - - - - 0 .018 .003 .031 .001 - 8 0 0.20 0.10 - 8 0.45 0.09 0.80 0.025 .030 .007 .047 .042 .006 - (1.0) 0.60 - 0.75 0.20 - - - 1.20 1.05 0.15 a b c d e e/2 h plane d l (l1) c 01 gage plane see detail detail a a 0.25 .026 bsc .252 bsc 20 .004 .169 .251 .173 .255 .007 - 20 0.10 0.65 bsc 6.40 bsc 4.40 6.50 - .177 .259 4.30 6.40 .012 0.19 4.50 6.60 0.30 bxn 2x n/2 tips seating aaa c e/2 indicator pin 1 2x 1 3 2 n
semtechfcorporation powerfmanagementfproductsfdivision 200fflynnfroad,fcamarillo,fcaf930 2 phone:f(805)f498-2 ffffax:f(805)f498-3804 www.semtech.co m contact information sc441d 20 land pattern -tssop-20 edp (.222) (5.65) z g y p (c) 4.10 .161 0.65 .026 0.40 .016 1.55 .061 7.20 .283 f x h inches dimensions z p y x dim c g millimeters h .126 3.20 f .157 4.00 3. 2. notes: 1. controlling dimensions are in millimeters (angles in degrees). failure to do so may compromise the thermal and/or thermal vias in the land pattern of the exposed pad shall be connected to a system ground plane. functional performance of the device. this land pattern is for reference purposes only. consult your manufacturing group to ensure your company's manufacturing guidelines are met.
sc441d 2 ?fsemtechf20 2 allfrightsfreserved.freproductionfinfwholeforfinfpartfisfprohibitedfwithoutfthefpriorfwrittenfconsentfoffthefcopyrightf owner.fthef informationf presentedf inf thisf documentf doesf notf formf partf off anyf quotationf orf contract,f isf believedf tof bef accuratef andf reliablef andf mayf bef changedf withoutf notice.f nof liabilityf willf bef acceptedf byf thef publisherf forf anyf consequencefoffitsfuse.fpublicationfthereoffdoesfnotfconveyfnorfimplyfanyflicensefunderfpatentforfotherfindustrialforf intellectualfpropertyfrights.fsemtechfassumesfnofresponsibilityforfliabilityfwhatsoeverfforfanyffailureforfunexpectedf operationf resultingf fromf misuse,f neglectf improperf installation,f repairf orf improperf handlingf orf unusualf physicalf orf electricalf stressf including,f butf notf limitedf to,f exposuref tof parametersf beyondf thef specifedf maximumf ratingsf orf operationfoutsidefthefspecifedfrange. semtechfproductsfarefnotfdesigned,fintended,fauthorizedforfwarrantedftofbefsuitablefforfusefinflife- supportfapplications,fdevicesforfsystemsforfotherfcriticalfapplications.finclusionfoffsemtechfproductsf infsuchfapplicationsfisfunderstoodftofbefundertakenfsolelyfatfthefcustomersfownfrisk.fshouldfafcustomerf purchasef orf usef semtechf productsf forf anyf suchf unauthorizedf application,f thef customerf shallf indemnifyf andf holdf semtechfandfitsfofcers,femployees,fsubsidiaries,fafliates,fandfdistributorsfharmlessfagainstfallfclaims,fcostsfdamagesf andfattorneyffeesfwhichfcouldfarise. notice:f allf referencedf brands,f productf names,f servicef namesf andf trademarksf aref thef propertyf off theirf respectivef owners.

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