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high efciency integrated driver for 4-strings of 150ma leds SC441A power management julyf23,f2009 www.semtech.com features applications description widefinputfvoltagefrangeffromf4.5vftof2 v 36vfmaximumfoutputfvoltage 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 integratedf2.5afpowerfswitch 700khzfswitchingffrequencyfforfsmallfsizeff adjustablefovpfforfcost-efectivefoutputfcapfselection open/short led protection thermalfprotectionfwithfauto-recovery thermallyfenhancedftssop-20fedpfpackage fullyfweeefandfrohsfcompliant ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? medium-sizedflcdfpanel notebookfdisplay automotivefcarfnavigationfdisplay sub-notebookfandftabletfcomputerfdisplays portablefmediafplayers ? ? ? ? ? thefsc44 afisfafhigh-efciencyfmultiplefstringfwledfdriv - erfwithfanfintegratedfboostfconverter.ffitfoperatesfoverfaf widefinputfrangeffromf4.5vftof2 vfwithfafmaximumfout - putf voltagefoff 36vf andf af2.5af 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. thefsc44 afalsoffeaturesfcomprehensivefopenfandfshort- 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. thefsc44 afisfavailablefinfafthermally-enhancedftssop- 20fedpfpackage. typical application circuit 1 4 vout ss pgnd ioset io1-4 comp ovpin agnd vin sw pwm en ovprtn sw fflag pgnd iognd SC441A 4 strings 1 10 vin (4.5v -21v) 2 edp pgnd ioset io1- 4 comp ss agnd vout ovpin
SC441A 2 ?f2009fsemtechfcorporation www.semtech.com pin confguration ordering information marking information notes: ( )favailablefinftapefandfreelfonly.ffafreelfcontainsf2,500fdevices. (2)favailablefinflead-freefpackagefonly.ffdevicefisfweeefandfrohsf compliant. ffffffffff(tssop-20fedp) ja = 39o c/w device package sc44 atetrtf (1,2) tssop-20fedp sc44 aevb evaluationfboard 5 5 4 4 3 3 2 2 1 1 d d c c b b a a io2 io4 pgnd io1 io3 en ss agnd comp iognd fflag vin vout ioset pwm ovprtn pgnd sw ovpin sw 1 11 20 10 sc44 af:fpartfnumber yywwf=fdatef(example:f0952) xxxxxxf=fsemtechflot#f(example:fa94a0 )
SC441A 3 ?f2009fsemtechfcorporation www.semtech.com 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-0.3ftof25v maximumfoutputfpowerfffffff22w sw,fovpin,fovprtn,fvout,fio ~io4fvoltagefffff-0.3ftof40vff 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~2 v outputfvoltagefffupftoff36v ledfcurrentffffupftof 50ma junctionftofambient () fffff39c/w maximumfjunctionftemperatureff 50c storageftemperaturefffff-65ftof+ 50c leadftemperaturef(soldering)f 0fsecffff260c unlessfotherwisefspecifed:fv in f= 2v,f-40cf SC441A 4 ?f2009fsemtechfcorporation www.semtech.com electrical characteristics (continued) notes: ( )ffguaranteedfbyfdesign. (2)ffforfachievablefpwmfdimmingfminimumfpulse-widthfinfapplications,fseefthefcorrespondingfcurvesfinftypicalfcharacteristics. parameter symbol conditions min typ max units control signals en,fpwmfhighfvoltage v en_h,f v pwm_h 2 v en,fpwmflowfvoltage 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 0.85 v ssfendfvalue v ss_end v in f=f2v 2.5 f v over-voltage protection ovpinfthreshold v ovpin_th ovpinf-fagnd .43 .52 .58 v ovpinfleakagefcurrent i ovpin v ovpin f=f20v 0. a ovprtnfsaturationfvoltage v ovprtn i ovprtn f=f00fa 60 mv ovprtnfleakagefcurrent i ovprtn v ovprtn 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-circuitfprotection v io_scp t j f=f25fc,fv io f~fv io4 2.2 2.35 2.55 v leakagefcurrent i io_leak enf=f0,fv io f~fv io4 f=fv in 0. a 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 over-temperature protection thermalfshutdownftemperature t otp 50 c thermalfshutdownfhysteresis t otp_h 30 c
SC441A 5 ?f2009fsemtechfcorporation www.semtech.com typical characteristics 149.7 149.8 149.9 150.0 150.1 150.2 150.3 150.4 150.5 150.6 150.7 -40 25 105 led current source setting (ma) 2.360 2.365 2.370 2.375 2.380 2.385 2.390 2.395 2.400 2.405 2.410 -40 25 105 led current source scp threshold (v) 0.75 0.77 0.79 0.81 0.83 0.85 0.87 0.89 0.91 0.93 -40 25 105 vout pull down current source (ma) 135 140 145 150 155 160 165 170 175 -40 25 105 sw saturation voltage at 1a (mv) 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) vin = 4.5v vin = 21v vout = vin + 3v ledfcurrentfsourcefscpfthreshold fvs.ftemperature averagefledfcurrentfsourcefsetting vs.ftemperature vin = 12v r ioset = 1.78k : vin = 12v temperaturef( o c) 4.29 4.30 4.31 4.32 4.33 4.34 4.35 4.36 -40 25 105 vin uvlo (v) 237 238 239 240 241 242 243 244 245 246 247 -40 25 105 uvlo hysteresis (mv) 2.50 2.60 2.70 2.80 2.90 3.00 3.10 3.20 -40 25 105 vin quiescent supply current (ma) vin = 4.5v vin = 21v vin = 12v ss sink/source 0.0 1.0 2.0 3.0 4.0 5.0 6.0 -40 25 105 source sink vin = 12v 4.00 4.50 5.00 5.50 6.00 6.50 7.00 7.50 -40 25 105 comp sink source source sink source sink vin = 12v
SC441A 6 ?f2009fsemtechfcorporation www.semtech.com typical characteristics (continued) 120 140 160 180 200 220 240 260 -40 25 105 fflag saturation voltage (mv) 40 45 50 55 60 65 70 75 -40 25 105 ovprtn saturation voltage (v) 0 100 200 300 400 500 600 700 800 900 10 20 40 60 80 100 120 140 160 led current source saturation voltage (mv) temperaturef( o c) ovpinfthresholdfvoltage fvs.ftemperature temperaturef( o c) temperaturef( o c) i ovprtn = 100ua ledfcurrentf(ma) ledfcurrentfsourcefsaturationfvoltagef vs.fledfcurrent t a = 25 o c ovprtnfsaturationfvoltage fvs.ftemperature fflagfsaturationfvoltagef vs.ftemperature i fflag = 2ma 80 82 84 86 88 90 92 94 80 160 240 320 400 480 560 600 efficiency (%) efciencyf(fp boost_output f/fp input ) vin = 12v vin = 5v vin = 21v boostfsectionfoutputfcurrentf(ma) condition:fvoutf=f36vf 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 0.2 0.5 1 2 5 10 20 30 40 50 pwm dimming minimum pulse width(us) pwmfdimmingfminimumfpulsefwidthf vs.fpwmfdimmingffrequency pwm dimming frequency (khz) condition:fvinf=f 2v,fvoutf=f30vf/f20mafxf4fstringsf pwmfdimmingfminimumfpulsefwidthf vs.fpwmfdimmingffrequency pwmfdimmingffrequencyf(khz) 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 0.5 1 2 5 10 20 30 40 50 pwm dimming minimum pulse width(us) condition:fvinf=f 2v,fvoutf=f30vf/f 50mafxf4fstringsf pwmfdimmingfminimumfdutyfcyclef vs.fpwmfdimmingffrequency pwmfdimmingffrequencyf(khz) condition:fvinf=f 2v,fvoutf=f30vf/f20mafxf4fstringsf 0 2 4 6 8 10 12 14 16 18 20 22 0.2 0.5 1 2 5 10 20 30 40 50 pwm dimming minimum duty cycle(%) pwmfdimmingfminimumfdutyfcyclef vs.fpwmfdimmingffrequency pwmfdimmingffrequencyf(khz) condition:fvinf=f 2v,fvoutf=f30vf/f 50mafxf4fstrings f 0 2 4 6 8 10 12 14 0.5 1 2 5 10 20 30 40 50 pwm dimming minimum duty cycle(%) ovpin 1.46 1.48 1.50 1.52 1.54 1.56 1.58 -40 25 105 vin = 12v
SC441A 7 ?f2009fsemtechfcorporation www.semtech.com typical characteristics (continued) ? ?? ?? ?? ?? ?? ? ? ?? ?? ? ? ? ?? ?? ?? ?? ? 10ma 10ma pwmfdimmingffrequencyf(khz) condition:fvinf=f 2v,fvoutf=f34.5vf/f 0mafxf4fstringsf pwmfdimmingfminimumfpulsefwidthf vs.fpwmfdimmingffrequency pwmfdimmingfminimumfpulsefwidth(us) 150ma ? ? ? ? ? ?? ?? ?? ?? ? ? ? ?? ?? ?? ?? ? pwmfdimmingffrequencyf(khz) condition:fvinf=f 2v,fvoutf=f34.5vf/f 50mafxf4fstringsf pwmfdimmingfminimumfpulsefwidthf vs.fpwmfdimmingffrequency pwmfdimmingfminimumfpulsefwidth(us)
SC441A 8 ?f2009fsemtechfcorporation www.semtech.com typical characteristics (continued) vin (10v/div) vout (20v/div) vss (2v/div) vsw (20v/div) start up time (20ms/div) conditions: vin = 19v, output = 30v / 150ma x 4 led strings conditions: vin = 12v, output = 27v / 20ma x 4 led strings vin (5v/div) vout (20v/div) vss (2v/div) vsw (20v/div) time (200ms/div) shut down conditions: vin = 12v, output = 27v / 20ma x 4 led strings vout accoupling (200mv/div) vsw (20v/div) time (1us/div) main power switching waveform time (400ns/div) main power switching waveform vout accoupling (100mv/div) vsw (10v/div) conditions: vin = 12v, output = 36v / 150ma x 4 led strings
SC441A 9 ?f2009fsemtechfcorporation www.semtech.com typical characteristics (continued) otp and otp recovery vin = 12v vout (20v/div) vss (2v/div) vsw (20v/div) conditions: vin = 12v, output = 36v / 150ma x 4 led strings time (40ms/div) led short circuit protection vin (10v/div) io2 (1v/div) vout (20v/div) io1 (5v/div) conditions: vin = 12v, io1 has one led short circuit, output = 36v / 150ma x 4 led strings time (10ms/div) led open circuit protection vin (5v/div) io2 (1v/div) vout (20v/div) io1 (10v/div) conditions: vin = 12v, io2 led string is open circuit, output = 36v / 150ma x 3 led strings time (10ms/div) conditions: vin = 12v, output = 36v / 50ma x 4 led strings time (10ms/div) vin = 12v io1 (5v/div) pwm (2v/div) sw (20v/div) pwm dimming
SC441A 0 ?f2009fsemtechfcorporation www.semtech.com 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 ovprtn over-voltagefprotectionfsensefsignalfreturnfpathfpin. 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.
SC441A ?f2009fsemtechfcorporation www.semtech.com block diagram figure 1. SC441A 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 ovprtn - 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 4.5ua 4.5ua s r q 0.9ma 0.9ma 1ua 1ua
SC441A 2 ?f2009fsemtechfcorporation www.semtech.com applications information SC441A detailed description thef sc44 af 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 afreceivesffeedbackffromfallfoff thefledfcurrentfsources,fallfledfstringsfcanfbefturnedfonf atfanyfgivenftime.ffaftypicalfapplicationfwouldfusef3- 0f backlightfledsfforfeachfstring,fdrivenfupftof 50ma.ff operation thefsc44 afcontrolsfthefboostfconverterfsetfpointfbasedf 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 af 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 afwillf 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 a,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 af isf inf normalf operation,f thenf thef sc44 af willf runf inf standbyf mode.fthefinternalfswitcherfandfthefledfcurrentfsourcef willfimmediatelyfturnfof.f noteC thefpwmfsignalfdoesfnotfafectfthefssfpinfnorfitsffnalfvalue.f main power operation sc44 afisfaf700khzffxed-frequency,fpeakfcurrent-modef step-upf switchingf regulatorf withf anf integratedf 2.5af (minimum)fpowerftransistor.f
SC441A 3 ?f2009fsemtechfcorporation www.semtech.com applications information (continued) therefarefsomefchoices. )fleavefsomefroomfbetweenfvinfrangefandfvo. 2)foperatefthefboostfconverterfatfnormalfloadf(lessfro) 3)fincreasesfthefboostfinductancef(l). over-current protection sc44 af providesf cycle-by-cyclef currentf limitingf forf itsf internalf switch.f iff thef switchf currentf exceedsf 3.32af (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 afincludesfanfexternalfprogrammingfover-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 5.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 afentersfafsoft-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, 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 afasffollows. 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 d v v in o 1 1 o o in v l r v * 10 * 6 . 1 1 1 2 2 t
SC441A 4 ?f2009fsemtechfcorporation www.semtech.com 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 short-circuit,f thatf stringfwillfbeflatchedfof.ffvoltagefisfmonitoredfiffitfexceedsf 2.35vfonfthefinternalfledfcurrentfsourcef(iofpins).f(thefiof voltagef onf anf abnormalf ledf stringf willf risef earlierf thanf otherf normalf ledf strings).f iff thef voltagef exceedsf 2.35vf onfanyfiofpin,fthefiofcurrentfsourcefwillflatchfoffandfthef fflagf willf gof high.f thef latchf isf resetf iff vinf fallsf belowf uvlof orf itf willf recyclef thef enf signal.f f otherf ledf stringsf operatefnormally.f iff allf iof pinf voltagesf reachf .07vf thenf thef internalf mainf switchfwillfbefoffuntilfanyfoffthefiofvoltagesfisflowerfthanf 970mv. 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 afwillfretryfwhenfssffallsfbelowf 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 af 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 afcanfresolvef 0sf(minimum),f pwmfdimmingfpulse-width. asf farf asf thef maximumf pwmf dimmingf pulse-width,f itf 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. 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 pwm off f t d min _ max 1
SC441A 5 ?f2009fsemtechfcorporation www.semtech.com applications information (continued) thefneededfdimmingfstepsfandfresolutions,fitfisfuncommonf tofrunfintofthefabovefd_maxfbeforefreachingf 00%.fwhilef mostfapplicationsfwillfnotfrunfintofd_max,fthefdesignerf shouldfbefawarefoffpossiblefparasiticfelementsffromfpwmf dimmingf interfacef tof thef pwmf pinf off sc44 a.f usually,f simplyfcheckingfsignalfd_maxfatfpwmfpinfoffsc44 afisf sufcient. linear dimming thef linearf dimmingf controlf isf availablef forf sc44 af byf applyingf anf externalf controlf voltagef onf iosetf pinf throughf anf externalf resistor-likef circuitf (shownf below).f externalfenvironmentfbrightnessfcompensationfcanfalsof befachievedfwhenfthefcontrolfvoltagefisfgeneratedfbyfaf lightfsensorfcircuit. 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 af ledf short- circuitf protectionf mayf falsef tripf whenf thef noisef levelf isf large.ffcertainfceramicfdecouplingfcapacitorfonfpinsfio f ~fio4ftofgndfarefusefulftofpreventfthefsc44 affromfnoisef infuence. asfafgeneralfguideline,fthefdecouplingfcapacitancefshouldf beflimitedfasffollows. 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 thefcalculatedfupperfboundfoffc_dcplefisfaboutf4.44nf.f 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 onefmayfusef3.9nfforflessfinfthefcircuit.ffinfsomefappli - cations,fcircuitfdesignersftendftofselectfthefdecouplingf capacitorsfinfthefrangefoff( 00pff~f nf).ffforfsomeflowf ledfcurrentf(e.g.f 0ma)fapplications,fitfisfrecommendedf tofaddf m- 0mohmfresistorffromfiofpinftofgndfinforderf tofreducefiofpinfvoltagefduringfpwmfdimming. parallel operation whenftwoforfmorefsc44 asfarefoperatingfinfparallelfforf 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 afvinf 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, 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(flf SC441A 6 ?f2009fsemtechfcorporation www.semtech.com thefinductorfpeakfcurrentffis,f thefconverterfwillfworkfinfccmfifflf>fl 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 a.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 af 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 ensuringfprecisionfledfcurrentfregulation.falthough thefmechanicsfoffregulationfandffrequencyfdependencef mayfbefcomplex,factualfselectionfoffoutputfcapacitorfcanf bef simplifedf becausef thisf capacitorf isf mainlyf selectedf forfthefoutputfripplefoffthefconverter.fassumefafceramicf 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. 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 af duef tof theirflowfforwardfvoltagefdropfandffastfswitchingfspeed.ff tablef4fshowsfseveralfdiferentfschottkyfdiodesfthatfworkf wellf withf thef sc44 a.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 l f d v i s in peak l ? ? = ? 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)
SC441A 7 ?f2009fsemtechfcorporation www.semtech.com layout guidelines thef sc44 af containsf af boostf converterf andf thef place - mentsf off thef powerf componentsf outsidef thef sc44 af shouldf followf thef layoutf guidelinesf off af generalf boostf converter.fthefevaluationfapplicationfcircuitfonfpagef 7f willfbefusedfasfanfexample.ffc2fandfc3farefinputfdecou - plingfcapacitorfforfsc44 afvinfpinfandfmainfpowerfinput.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 a.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 throughfr 4fforfbetterfnoisefimmunity. applications information (continued)
SC441A 8 ?f2009fsemtechfcorporation www.semtech.com evaluation application circuit 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 40v,f3afschottkyfdiode sma b340 diodesforfany 8 l 6.8h,f6.6a dr25 6.8h copperforfany 9 r,fr4 2 %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 r8,fr0,fr, r2,fr3 5 5%fsmdfresistor sm_0603 r any 5 u controller edpftssop-20 sc44a semtech evaluation board bill of materials 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 c2 10uf/25v c2 10uf/25v d1 d1 c9 4.7uf/50v c9 4.7uf/50v r10 1r r10 1r c15 1nf c15 1nf c3 n.p. c3 n.p. r4 10k r4 10k c8 4.7uf/50v c8 4.7uf/50v r11 1r r11 1r r9 1.5k r9 1.5k u1 SC441A u1 SC441A io2 1 io1 2 iognd 3 agnd 4 ss 5 comp 6 en 7 ioset 8 pwm 9 vout 10 fflag 11 vin 12 ovprtn 13 ovpin 14 pgnd 15 sw 16 sw 17 pgnd 18 io4 19 io3 20 edp 21 c16 1nf c16 1nf r13 1r r13 1r r5 220k r5 220k r14 0r r14 0r c1 1nf c1 1nf r6 rioset r6 rioset r7 10k r7 10k c14 1nf c14 1nf c4 2.2uf/25v c4 2.2uf/25v c17 1nf c17 1nf c7 n.p. c7 n.p. r12 1r r12 1r r1 0r r1 0r r8 1r r8 1r r3 10k r3 10k c5 47n c5 47n c6 100nf c6 100nf r2 10k r2 10k
SC441A 9 ?f2009fsemtechfcorporation www.semtech.com outline drawing - tssop-20 edp ?f2009fsemtechfcorporation 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
SC441A 20 ?f2009fsemtechfcorporation www.semtech.com land pattern -tssop-20 edp semtechfcorporation powerfmanagementfproductsfdivision 200fflynnfroad,fcamarillo,fcaf930 2 phone:f(805)f498-2 ffffax:f(805)f498-3804 www.semtech.co m contact information . . c 4.1 .11 . . .4 .1 1. .1 . . f ics disis di c iis .1 . f .1 4. . . s 1. ci disis a i iis as i ds. fai d s a cis a ad a ias i ad a f sd ad sa b ccd a ss d a. fcia fac f dic. is ad a is f fc ss . cs afaci s cas afaci idis a .

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