high efciency integrated driver for 4-strings of 150ma leds SC445 power management revisionf2.1 1 features widefinputfvoltagefrangeffromf4.5vftof27v sustain fast vin fuctuation up to 5v/s 42vfmaximumfoutputfvoltage drivesfupftof40fwledsfinf4fstringsf programmable led current for up to 150ma per string +/- 2% string-to-string current matching up to 90% efciency widef0.2%ftof100%fpwmfdimmingfrange enablefanalogfdimming integratedf3.0afpowerfswitch 700khzfswitchingffrequencyfforfsmallfsizeff adjustablefovpfforfcost-efectivefoutputfcapfselection open/short led protection short led protection enable/disable thermalfprotectionfwithfauto-recovery thermallyfenhancedftssop-20fedpfpackage lead-free,fhalogen-freefandfweee/rohsfcompliant ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? description thefSC445fisfafhigh-efciencyfmultiplefstringfwledfdriverf withf anf integratedf boostf converter.f f itf operatesf overf af widef inputf rangef fromf 4.5vf tof 27vf andf canf sustainf fastf vinftransientfupftof5v/s.ffitfcanfdrivefupftoffortyfwledsfinf 4fstringsfwithfcurrentfupftof150mafperfstring.fffthefstring- to-stringf currentf matchingf isf 2%f typical,f 3%f maximum.ff thefoverallfefciencyfisfgreaterfthanf90%fdueftoftheflowf currentfsensefvoltagefandfaflow-impedancefinternalfpow - erfswitch.fthefwidefpwmfdimmingfrangefboastsfafratiofoff 500:f1. thef700khzfswitchingffrequencyfenablesfthefuserftofop - timizefthefexternalfcomponentfsizesfforfefciency.ffwhenf therefareffewerfthanf10fledsfinfeachfstring,fusersfcanfad - justfthefoutputfvoltagefprotectionfyieldingfanfallowablef reductionfinfassociatedfcosts,fsizefandfvoltagefratingsfoff thefoutputfcapacitor. thefSC445falsoffeaturesfcomprehensivefopenfandfshort- circuitf ledf protectionf functions.f itf disablesf thef corre - spondingfstringsfwithfledfopenforfledfshortfconditionsf whilefmaintainingfnormalfoperationfoffother,funafectedf ledfstrings.ffthisffeaturefallowsflcdfpanelsftofremainfview - ablefevenfunderfledffailure,fwirefdisconnect,forfshort-cir - cuitf conditions.fthef internalf thermalf shutdownf protectsf theficffromfoverheatingfatfabnormalfconditions. thefSC445fisfavailablefinfafthermally-enhancedftssop-20f edpfpackage. typical application circuit 1 4 vout ss pgnd ioset io1 - 4 comp ovpin agnd vin sw pwm en sw fflag pgnd iognd SC445 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 ? ? ? ? ?
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