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| confidential datasheetversion1.1 jun13 th 2013 map3242C4channelleddriverforhighbrightness leds 1 orderinginformation typicalapplication partnumber top marking ambient temperaturerange package rohsstatus map3242shrh map3242 40 to+85 28leadshsop halogenfree map3242sirh map3242 40 to+85 20leadssoic halogenfree MAP3242TERH map3242 40 to+85 20leadsetssop halogenfree applications highbrightnesswhiteledbacklightingforlcd tvsandmonitors generalledlightingapplications datasheet map3242 4 channelleddriv erforh i ghbrightnessleds generaldescription map3242 is a 4channel led driver optimized for ledbacklightapplicationtargetingmidandlarges ize lcd module. map3242 uses the boost mosfet externallyand4channelcurrentsourcesinternally for drivinghighbrightnesswhiteleds. map3242has65vabsolutemax.ratingfbpinsand inputvoltageisrangedfrom8.5v~36vandmaxled currentis240maperchannel. map3242 features internal softstart and 2.5% led current accuracy including matching between channels map3242 has various protections like output over voltage, adjustable led short, led open, open schottkydiodeanduvlo. map3242 has initial open fb detection function to notboosttheoutputvoltagetoovplevelexceptle d openevent. map3242isavailable28leadshsop,20leadssoic and etssop with halogenfree (fully rohs compliant). features 8.5vto36vinputvoltagerange driveupto4channels 65vfbpinvoltage 0.8vminheadroomvoltage@150ma 240maoutputcurrentperchannel 2.5%currentaccuracy initialopenfbdetectionfunction programmableboostswitchingfrequency (100khz~500khz) ledcurrentsetbyboth pwmandexternaldcvoltage boostovercurrentprotection outputovervoltageprotection adjustableledshortprotection ledopenprotection schottkydiodeopenprotection uvlo
confidential datasheetversion1.1 jun13 th 2013 map3242C4channelleddriverforhighbrightness leds 2 pinconfiguration 1 2 3 4 5 6 28 27 26 25 24 23 8 21 9 20 10 11 12 13 19 18 17 16 hs 2 hs 1 7 22 14 15 hsop28l soic /etssop20l functionalblockdiagram thermal shutdown sr q confidential datasheetversion1.1 jun13 th 2013 map3242C4channelleddriverforhighbrightness leds 3 pindescription name 28leads hsop 20leads etssop 20leads soic description vin 1 1 1 powersupplyinput.needexternalinputcapacitor. agnd 3 2 2 analogground comp 5 3 3 internalerroramplifiercompensation(note1) vldo 6 4 4 internal5vregulatoroutput.needexternalcapacit ortostabilizetheregulator adim 8 5 5 settingforledcurrentthruexternaldcvoltage iset 9 6 6 settingforledcurrentreferenceresistor(note2) en 10 7 7 enable.activehigh. fsw 11 8 8 settingforboosterswitchingfrequency(note3) fb4 12 9 9 ledcurrentsinkforch4 fb3 14 10 10 ledcurrentsinkforch3 fb2 15 11 11 ledcurrentsinkforch2 fb1 17 12 12 ledcurrentsinkforch1 pgood 19 13 13 powergoodstatusopendrainoutput(normal:open, protection:internalgnd) lgnd 20 ledcurrentsinkground pgnd 21 14 14 powerground ovp 22 15 15 outputovervoltagesense(note4) cs 23 16 16 externalboostcurrentsense(note5) gate 24 17 17 gatedriveroutputforexternalboostmosfet pwm 25 18 18 pwmsignalinputfordimming(note6) vdd 26 19 19 internal10vregulatoroutput.needexternalcapaci tortostabilizetheregulator vls 28 20 20 settingforledshortdetectionlevelthruexternal dcvoltage 2,4,7,13, 16,18,27 noconnection hs1,2 connecttogndforheatsinkingpurpose(note7) exposed pad connecttogndbymultipleviasforheatsinking purpose(note7) note1 :connectexternalcapacitorandresistortocompp in.refertoatypicalapplicationdiagram note2 :theresistorvalueonisetpincontrolsthefull scalelevelofsinkcurrentonfbpins.donotlea vethispinopen. note3 :connectexternalresistortosettheoscillatorf requencyfrom100khzto500khz note4 :.connectcenternodeofresistivevoltagedivider fromoutputtoground.refertoatypicalapplicati ondiagram note5 :connectexternalresistortopgndtosensetheex ternalpowermosfetdraincurrent note6 :thisexternalpwmsignalisusedforbrightnessc ontrol note7 :notconnectedinternally. confidential datasheetversion1.1 jun13 th 2013 map3242C4channelleddriverforhighbrightness leds 4 absolutemaximumratings (note1) symbol parameter min max unit v vin supplyvoltage 0.3 40 v v gate gatedriveroutput 0.3 14 v v vdd, vddpin 0.3 14 v v en ,v cs ,v vldo ,v pwm ,v comp ,v ovp , v vls , v iset, v pgood, v fsw, v adim en, cs, vldo, pwm, comp, ovp, vls, iset, pgood, fsw,adimpin 0.3 6 v v fb1~4 ledcurrentsinkpin 0.3 65 v i fb1~4 ledcurrentsinkpin 240 ma t pad solderinglead/padtemperature10sec 300 c t j junctiontemperature 40 +150 c t s storagetemperature 65 +150 c esd hbmonallpins(note2) 2000 +2000 v mmonallpins(note3) 200 +200 note 1 : stresses beyond the above listed maximum ratings may damage the device permanently. operating above the recommended conditions for extended time may stress the device and affect device reliability. also the device may not operate normally above the recommendedoperatingconditions.thesearestress ratingsonly. note2 :esdtestedperjesd22a114. note3 :esdtestedperjesd22a115. recommendedoperatingconditions (note1) parameter min max unit v vin supplyinputvoltage 8.5 36 v i fb1~4 ledcurrentsinkpin 90 240 ma v fb1~4 ledcurrentsinkpin 65 v t a ambienttemperature(note2) 40 +85 c note1 :normaloperationofthedeviceisnotguaranteed ifoperatingthedeviceoveroutsiderangeofrecom mendedconditions. note2 :theambienttemperaturemayhavetobederatedif usedinhighpowerdissipationandpoorthermalre sistanceconditions. packagethermalresistance (note1) parameter ja jc unit map3242shrh 28leadshsop 45.1 28.7 /w map3242sirh 20leadssoic 68.5 36.3 /w MAP3242TERH 20leadsetssop 64.1 9.3 /w note1 :multilayerpcbbasedonjedecstandard(jesd517 ) confidential datasheetversion1.1 jun13 th 2013 map3242C4channelleddriverforhighbrightness leds 5 electricalcharacteristics unlessnoted,v in =12v,c in =1.0 f,andtypicalvaluesaretestedatt a =25 c. parameter testcondition min typ max unit generalinputoutput v vin inputvoltagerange 8.5 36 v i q quiescentcurrent drivingfbsatmin.settingwith noload 5 10 ma i sd groundpincurrentin shutdown v in =12v,v en =0v noloadcurrentonfb 40 a v en logicinputlevelon enpin v en_l :logiclow 0.8 v v en_h :logichigh 2.2 r en pulldownresistoronenpin 250 500 k v uvlo undervoltagelockout thresholdvoltageonvddpin releaseuvlo 7.0 7.5 v hysteresis 1.0 oscillator f sw internaloscillator frequency r fsw =250k 180 200 220 khz r fsw =100k 425 500 575 d max max.dutycycle 85 90 % reference v vldo 5vldovoltage v in >15v,noloadcurrent 4.75 5 5.25 v i vldo 5vldosourcecurrent v in >15v,noloadcurrent 10 ma v vdd ldovoltageforgatedriver v in >15v,noloadcurrent 8.5 10 11.5 v protection t sd thermalshutdown temperature shutdowntemperature 150 c hysteresis, t sd 25 v ovp overvoltagethreshold onovppin risingovervoltagelimitonovppin 2.35 2.5 2.65 v hysteresis, v ovp 0.1 v led_short ledshortprotection thresholdonfbpins v vls =1v 5 v v vls =3v 15 t scp ledshortprotectiontime f sw =500khz(note1,2) 8.192 ms v cs boostovercurrentprotection thresholdoncspin 0.57 0.6 0.63 v v open ledopenprotection thresholdonfbpins i led =90ma 0.09 v i led =240ma 0.24 v sbdopen sbdopenprotection thresholdonovppin (note1) 0.1 v ledcurrentsinkregulator v fb1~4 min.fb1~fb4voltage i led =150ma,v adim =1.5v 0.8 v i fb currentaccuracy i led =120ma,v adim =1.2v 2.5 % i fb_max currentsinkmax.current v adim =2.4v 240 ma i fb_leakage currentsinkleakagecurrent v pwm =0v 5 ua v adim adiminputvoltagerange 0.9 2.4 v r adim pulldownresistoronadimpin 250 500 k pwminterface f pwm pwmdimmingfrequency 0.1 2.0 khz v pwm logicinputlevelon pwmpin v pwm_l :logiclow 0.8 v v pwm_h :logichigh 2.2 t on_min min.ontime(note1) f sw =100khz 30 us r pwm pulldownresistoronpwmpin 250 500 k boostmosfetgatedriver v gate gatedrivevoltage v in >15v 8.5 10 11.5 v i source gatesourcecurrent v in >15v,v gate =0.9*v vdd 20 ma i sink gatesinkcurrent v in >15v,v gate =0.1*v vdd 20 ma t rise gateoutputrisingtime gateload:10 /1nf 0.1 0.5 us t fall gateoutputfallingtime gateload:10 /1nf 0.1 0.5 us confidential datasheetversion1.1 jun13 th 2013 map3242C4channelleddriverforhighbrightness leds 6 electricalcharacteristics(continued) parameter testcondition min typ max unit softstart t ss softstarttime f sw =200khz(note1) 8.5 13 ms pgoodoutput(opendrain) r pgood internalpgoodresistance v pgood =1v 50 200 note1 :theseparameters,althoughguaranteedbydesign, arenottestedinmassproduction. note2 : 4096 1 = fsw tscp confidential datasheetversion1.1 jun13 th 2013 map3242C4channelleddriverforhighbrightness leds 7 typicaloperatingcharacteristics unlessotherwisenoted,v in =24v,cin=220uf,cout=100uf,riset=10k , rfsw=250k andt a =25 c. temp.vs.i q temp.vs. i sd temp.vs.v dd temp.vs.v ldo temp.vs.f sw temp.vs.v uvlo confidential datasheetversion1.1 jun13 th 2013 map3242C4channelleddriverforhighbrightness leds 8 typicaloperatingcharacteristics unlessotherwisenoted,v in =24v,cin=220uf,cout=100uf,riset=10k , rfsw=250k andt a =25 c. temp.vs.v ovp temp.vs.v cs v adim .vs.min.v fb (headroom) v adim .vs.i led dutycycle.vs.v cs confidential datasheetversion1.1 jun13 th 2013 map3242C4channelleddriverforhighbrightness leds 9 typicaloperatingcharacteristics unlessotherwisenoted,v in =24v,cin=220uf,cout=100uf,riset=10k , rfsw=250k andt a =25 c. ccmoperation vout gate comp i_l 10v/div 10v/div 1v/div 2a/div dcmoperation vout gate comp i_l 10v/div 10v/div 1v/div 2a/div turnon(softstart) turnoff 10v/div 10v/div 1v/div 2a/div vin 10v/div 5v/div 5v/div 1a/div min.dimming(2clock) min.dimming(3clock) pwm iled 10v/div 50ma/div uvlorelease uvlolockout 20v/div 10v/div 10v/div 5v/div vout gate comp i_l en pwm i_l vout gate 10v/div 2v/div vin vdd vout gate 20v/div 10v/div 10v/div 5v/div vin vdd vout gate pwm iled 10v/div 50ma/div vout gate 10v/div 2v/div confidential datasheetversion1.1 jun13 th 2013 map3242C4channelleddriverforhighbrightness leds 10 typicaloperatingcharacteristics unlessotherwisenoted,v in =24v,cin=220uf,cout=100uf,riset=10k , rfsw=250k andt a =25 c. overvoltageprotection(ledallopen) vout pgood vfb iled 10v/div 1v/div 10v/div 100ma/div sbdopenprotection vin en/pwm adim drain 20v/div 5v/div 2v/div 10v/div ledopenprotection ledshortprotection 10v/div 5v/div 10v/div 100ma/div thermalshutdown gate pgood 5v/div vout pgood vfb (notopen) i led (notopen) vout 10v/div 10v/div 10v/div 5v/div 10v/div 100ma/div vout pgood vfb (short) iled (sh ort) confidential datasheetversion1.1 jun13 th 2013 map3242C4channelleddriverforhighbrightness leds 11 applicationinformation currentmodeboostswitching controlleroperation the map3242 employs current mode control boost architecture that has a fast current sense loop and a slowvoltagefeedbackloop.sucharchitectureachie ves a fast transient response that is essential for the led backlightapplication. dynamicheadroomcontrol the map3242 features a proprietary dynamic headroom control circuit that detects the lowest voltage from any of the fb1fb4 pins. this lowest channelvoltageisusedasthefeedbacksignalfor the boostcontroller.sinceallledstacksareconnecte din parallel to the same output voltage, the other fb p ins will have a higher voltage, but the regulated curre nt source circuit on each channel will ensure that eac h channelhasthesamecurrent. internal5v/10vregulator the map3242 has builtin 5v ldo regulator to supply internalanalogandlogicblocks.theldoispowere dup whentheenpinislogichigh.a2.2ufbypasscapac itoris requiredonthevldopinforstableoperationofth eldo. a10vldoisusedtodriveexternalmosfetconnecte d tothegatepin.a2.2ufbypasscapacitorisrequir edon thevddpinforstableoperationoftheldo. dimmingscheme thebrightnesscontroloftheledsisperformedby a pulsewidthmodulationofthechannelcurrent.when a pwm signal is applied to the pwm pin, the current generatorsareturnedonandoffmirroringthepwm pin behavior. whenpwmsignalstaysatlowlevel(<0.8v)foralo ng time, the map3242 turns off the boost circuitry, bu t internal circuit is enabled so the map3242 increase s theoutputvoltagepromptly. if the ontime of inputted pwm signal is less than 3 fsw clock, the map3242 controls the min. ontime of output pwm by 2 or 3 fsw clock to prevent abnormal turnofforopreation.forexample, fsw=100khz>t on_min =20usto30us fsw=500khz>t on_min =4usto6us paralleloperation even the map3242 has 4 channels and 240ma led current capability per channel, 2 channels and 480m a applicationcanbesupportedbytying2fbsinto1ch ,so theledcurrentcapabilitycanbeincreasedto480m a. ledcurrentadjustment the map3242 sets the led current through the voltage level on the adim pin. adim pin voltage vs. led current is as following table. a 10k /1% resistor mustbeconnectedbetweentheisetpinandground. adimvoltage[v] ledcurrent[ma] 0.9 90 1.0 100 1.2 120 1.4 140 1.6 160 1.8 180 2.0 200 2.2 220 2.4 240 the relationship between adim pin voltage, riset valueandledcurrentisdefiendbyfollowingequat ion. 1000 ] [ ] [ ] [ = k iset adim led r v v ma i the map3242 offers protection functions to limit ex cess led current increase at abnormall iset and adim pin voltage. if the adim or iset pin voltage is at foll owing conditions abnormally, the map3242 turns off the ga te outputandinternalledcurrentsinkmosfets. v_iset 0.3v v_adim 3.5v someapplicationneedtodecreaseledcurrentfurth erat abnormal pin voltage. in this case, a 2.5 ~ 2.7v ze ner clamp is recommendable on the adim pin like followi ng circuit. confidential datasheetversion1.1 jun13 th 2013 map3242C4channelleddriverforhighbrightness leds 12 boostswitchingfrequency the switching frequency of the map3242 should be programmed between 100khz and 500khz by an external resistor connected between the fsw pin and ground. do not leave this pin open. the approximate operatingboostswitchingfrequencycanbecalculat ed byfollowingequation. ] [ 50 ] [ = k r mhz f fsw sw ifthefswpinvoltageisdecreaedtobeloworequa l to 0.6v abnormally the map3242 turns off the gate outputtoprotectexcessswitchingfrequencyincrea se. startup (1) the map3242 has softstart circuitry internally andthesoftstarttime(tss)istypical8.5ms. (2) initial open fb detection function therecanbeexistapplicationswhichdonotuse all the fb pins(4 channel). conventional multi channel led drivers boost the output voltage to ovpleveltocheckopenfb(s). the map3242 detects unused fb(s) and excludes corresponding fb(s) automatically from headroom control before startup. the unused fb(s) must be conntected to gnd. thisensures the output voltage is not boosted to ovp level at startup. if the unused fb(s) are not connected to gnd,theoutputvoltageisboosteduptoovplevel likeconventionalboostleddriver. these features significantly reduce the startup currentandpreventabnormaloperationatstartup. pgoodoutput the pgood pin is at its highimpedance state when noerrorisdetected.however,ifanyoffollowing exists, pgoodpingoesintolowimpedancestate. (1)ledopenprotection (2)ledshortprotection (3)thermalshutdown the pgood pin can be cleared by recycling the en pinorapplyingacompletepoweronreset(por). undervoltagelockout if the input voltage falls below the uvlo level of typical 7v on the vdd pin, the device will stop switchingandbereset.operationwillrestartwhen the vddpinvoltagerisesmin.1vhysteresisoverthel ock out threshold. this ensures failsafe operation whe n theinputvoltagefallsbelowmin.vinvoltageofi c. outputovervoltageprotection toprotecttheboostconverterwhentheloadisope n or the output voltage becomes excessive for any reason,themap3242featuresadedicatedovervoltag e feedbackinput.theovppinisconnectedtothecen ter tap of a resistive voltagedivider from the high vo ltage output. whentheovppinvoltageexceedstypical2.5v,a comparator turns off the external power mosfet. thi s switchisreenabledaftertheovppinvoltagedrop stypical 100mvhysteresisbelowtheprotectionthreshold.th isover voltageprotectionfeatureensurestheboostconver terfail safe operation when the led channels are disconnect ed fromtheoutput. a 5v zener diode is recommendable to avoid pin damagewhenthervoplresistorisopenabnormally. 2.5v + - 5vzener theovpvoltageofoutputvoltagecanbecalculated by followingequation. ) 1( 5.2 ] [ _ ovpl ovph ovp out r r v v + = sbdopenprotection when ovp pin voltage is less than 0.1v, the map3242turnsoffthegateoutput. this protects the driver from damage if the output schottkydiodeisopen(defectiveorpoorsoldercon tact). confidential datasheetversion1.1 jun13 th 2013 map3242C4channelleddriverforhighbrightness leds 13 boostovercurrentprotection the map3242 features overcurrent protection (ocp)bysensingcspinvoltage.thiscspinisuse d forinductorcurrentsensingforcurrentmodecontr olas well. if the cs pin voltage exceeds typical 0.6v, the map3242turnsoffthegateoutput. the internal ocp sensing voltage decreases with increase of gate dutycycle due to internal slope compensationwhichensuresstableccmoperation. followinggraphshowstherelationshipbetweengate dutycycleandinternalocpsensingtypicalvoltage . 56125 .0 21255 .0 ] .[ _ _ + ? = d v typ ocp vcs rcs setting procedure (1) chooseboostinductorvalue once the led current, the input and output voltage and the switching frequency are fixed, the inductan ce value defining the boundary between dcm and ccm opreationcanbecalculatedas; sw o b f d d r h l ? = 2 ) 1( ] [ 2 where,ro=vout/iout (2) find peak inductor current at selected boost inductance l f d v i sw in dcm peak l = _ _ l f d v i i sw in ovp in ccm peak l + = 2 ) ( _ _ the rcs value should be choosen that the output voltage can be boosted up to ovp level. and the iou t value should be considered with max. 3 channel because the ovp is occurred led open event only. thus, in fb out ovp out ovp in v n i v a i ? = )1 ( ] [ _ ) ( :effieincy n fb :thenumberofusingchannel (3) findtypicalvcs_ocpvalueatgivend 56125 .0 21255 .0 ] .[ _ _ + ? = d v typ ocp vcs (4) findrcsvalue in order to avoid touching the current limit during normal operation, the voltage across the current sensing resistor rcs should be less than 80% of the worstcasecurrentlimitvoltage. peak l typ ocp cs cs i v r _ _ _ 8.0 ] [ = example vin=24v,vout_ovp=65v,=90%, iled/ch=100ma, ledstring=4x18,fsw=200khz (1) chooseboostinductorvalue ] [ 37 2 ) 1( 2 h f d d r l sw o b = ? = in this case, choosed inductance value is 47uh for ccmoperation. (2) findpeakinductorcurrent ] [9.0 )1 4( / _ ) ( a v i v i in ch led ovp out ovp in = ? = ] [ 61 .1 2 ) ( _ _ a l f d v i i sw in ovp in ccm peak l = + = (3) findtypicalvcs_ocpvalueatgivend ] [ 443 .0 56125 .0 21255 .0 _ _ v d typ ocp vcs = + ? = (4) findrcsvalue ] [ 22 .0 8.0 _ _ _ = = peak l typ ocp cs cs i v r mx provides design spreadsheet for map3242 ver0.1 foreaseexternalcompontscalculation. confidential datasheetversion1.1 jun13 th 2013 map3242C4channelleddriverforhighbrightness leds 14 ledopenprotection incasethevoltageonanyofledcurrentsinkpins (fb1~4)isbelowledopenprotectionthresholddue toledopen duringnormaloperation,theoutputvoltageisboos tedupto100%ofovplevelandthemap3242automat icallyexcludes thecorrespondingchannelandremainingstring(s)w illcontinueoperation. theprotectionstatusislatchedandthepgoodpin goesintolowimpedancestate.thepgoodpincanbe cleared byrecyclingtheenpinorapplyingacompletepowe ronreset(por). ledshortprotection the map3242 can set led short detection voltage throughadjustingvlspinvoltage.inputvoltagera nge ofvlspinisfrom1vto3vandledshortdetection voltage on the fb pins is determined by following equation. following is a typical application circuit. more th an 1nf capacitor is recommendable to bypass spike noise. if the voltage at any of the fb14 pins exceeds led short detection voltage due to led short during no rmal operation and persists for tscp, the map3242 automa tically turns off the corresponding channel and rem aining channel(s)willcontinueoperation. theprotectionstatusislatchedandthepgoodpin goesintolowimpedancestate.thepgoodpincanbe cleared byrecyclingtheenpinorapplyingacompletepowe ronreset(por). whenled(s)is(are)openonanychannel,theoutput voltageisboostedupto100%ofovplevelandthi scan cause abnormal led short protection due to high fb voltage. to avoid this abnormal operation, the map3 242 disablestheledshortprotectionfunctionwithrel atedtomin.fbvoltageconditions. min.vfb 2.60v=>ledshortprotectiondisable min.vfb 2.15v=>ledshortprotectionenable vls short led v v v = 5 ] [ _ confidential datasheetversion1.1 jun13 th 2013 map3242C4channelleddriverforhighbrightness leds 15 operationtimingchart each of capacitors which is connected on vldo and v dd pin begins charing after en is turnedon and adi m voltageissetup.oncethevddvoltagereachestyp ical7v,theinternaluvloisreleased.themap3242 checks theinitialopenfb(s)andexcludescorrespondingf b(s)fromheadroomcontrolbeforeinternalpgsigna lissetup. the unused fb(s) must be connected to gnd. internal controller starts boosting with first pwm input and performssoftstart.aftersoftstartisendordur ingsoftstartperiod,theoutputvoltageisbooste duptoregulation voltage(total forward voltage of led bar + fb volta ge) without touching ovp level and the controller p erforms headroomcontrol. thepgoodoutputbecomesvalidafterthevldocapac itorisfullychargedafterenisturnedon.itdep enson thecapacitanceofvldocapacitor.itisrecommeded thatthepgoodvalidtimebetakenabout1msafter enis turnedon. themap3242booststheoutputvoltageonlyincondi tionthatvinisappliedanden,pwmandadimistu rnedon.and thereisnolimitationwithregardtoturnonseque nce.butincasethatvin(inputvoltageofbooster) isappliedlastlyafter en,pwmandadimisturnedon,thestartupcurrent isincreasedbecausetheoutputvoltageisboosted from0v. ifthepwmsignalremainslogiclowforoverthan1 6.4ms(1/fsw*8192)at500khzboostswitchingfrequ encyduring normaloperation,thecontrollerregardsitasdim zerocondition.becauseofdischargeofoutputcapa citorthroughthe ovpsensingresistorsduringthedimzerotime,the outputvoltagegettingdeclined.themap3242perfo rmssoftstartas soonaspwmsignalrisestoboosttheoutputvoltag erapidly. thecontrollerstopsswitchingrightafterenistu rnedoff. confidential datasheetversion1.1 jun13 th 2013 map3242C4channelleddriverforhighbrightness leds 16 externalcomponentsselection inductor the inductor value should be decided before system design. because the selection of the inductor affec ts the operating mode of ccm(continuous conduction mode)ordcm(discontinuousconductionmode). the inductance value defining the boundary between dcmandccmopreationcanbecalculatedas; sw o b f d d r h l ? = 2 ) 1( ] [ 2 where,ro=vout/iout in ccm operation, inductor size should be bigger, even though the ripple current and peak current of inductor can be small. in dcm operation, even rippl e current and peak current of inductor should be larg e whiletheinductorsizecanbesmaller. the inductor dc current or input current can be calculatedasfollowingequations. in out out in v i v a i = ] [ ?Cefficiencyoftheboostconverter thenthedutyratiois, d out d in out v v v v v d + + ? = v d C forward voltage drop of the output rectifying diode when the boost converter runs in dcm ( l < l b ), it takes the advantages of small inductance and quick transientresponse.theinductorpeakcurrentis, l f d v i sw in dcm peak l = _ _ theconverterwillworkinccmifl>l b ,generallythe converter has higher efficiency under ccm and the inductorpeakcurrentis, l f d v i i sw in in ccm peak l + = 2 _ _ boost mosfet thecriticalparametersforselectionofamosfet are: 1.maximumdraincurrentrating,i d(max) 2.maximumdraintosourcevoltage,v ds(max) 3.onresistance,r ds(on) 4.gatesourcecharegq gs andgatedrainchareq gd 5.totalgatecharge,q g the maximum current through the power mosfet happens when the input voltage is minimum and the outputpowerismaximum.themaximumrmscurrent throughthemosfetisgivenby; max max in max rms d i i = ) ( ) ( theoffstatevoltageofthemosfetisapproximatel y equaltotheoutputvoltageplusthediodev f .therefore, v ds(max) ofthemosfetmustberatedhigherthanthe maximumoutputvoltage(ovpvoltage). the power losses in the mosfet can be separated into conduction losses and switching losses. the conduction loss, pcond, is the i2r loss across the mosfet.theconductionlossisgivenby; k i r p rms on ds cond = 2 ) ( wherekisthetemperaturecoefficientofthemosfe t. the switching loss is related to q gd and q gs1 which determine the commutation time. q gs1 is the charge betweenthethresholdvoltageandtheplateauvolta ge when a driver charges the gate, which can be read i n thechartofv gs vs.q g ofthemosfetdatasheet.q gd is the charge during the plateau voltage. these two parametersareneededtoestimatetheturnonandt urn offloss. sw in ds plt dr g gd sw in ds th dr g gs sw f i v v v r q f i v v v r q p ? + ? = 1 wherev th isthethresholdvoltage,v plt istheplateau voltage, r g is the gate resistance, v ds is the drain sourcevoltage,v dr isthedrivevoltage the total gate charge, q g , is used to calculate the gatedriveloss.theexpressionis sw dr g dr f v q p = fast switching mosfets can cause noise spikes whichmayaffectperformance.toreducethesespike s adriveresistorcanbeplacedbetweengatepinand themosfetgate. confidential datasheetversion1.1 jun13 th 2013 map3242C4channelleddriverforhighbrightness leds 17 output rectifying diode schottky diodes are the ideal choice for map3242 due to their low forward voltage drop and fast switching speed. make sure that the diode has a voltage rating greater that the possible maximum outputvoltage.thediodeconductscurrentonlywhe n thepowerswitchisturnedoff. input capacitor in boost converter, input current flows continuousl y into the inductor; ac ripple component is only proportional to the rate of the inductor charging, thus, smallervalueinputcapacitorsmaybeused.ensure the voltage rating of the input capacitor is suitable t o handlethefullsupplyrange. a capacitor with low esr should be chosen to minimizeheatingeffectsandimprovesystemefficie ncy. output capacitor the output capacitor acts to smooth the output voltage and supplies load current directly during t he conduction phase of the power switch. output ripple voltage consists of the discharge of the output capacitor during the fet ton period and the voltage dropduetoloadcurrentflowingthroughtheesrof the output capacitor. the ripple voltage is shown in followingequation. esr i f c d i v out sw out out out + = assume a ceramic capacitor is used. the minimum capacitanceneededforagivenripplecanbeestima ted byfollowingequation. out sw out out out in out v f v i v v c ? = ) ( loop compensation themap3242controlsincurrentmode.currentmode easily achieves compensation by consisting simple single pole from double pole that lc filer makes at voltage mode. in general, crossover frequency is selected from 1/3 ~ 1/6 range of the switching frequency.iffcislarge,thereispossibilityof oscillation tooccur,althoughtimeresponsegetsbetter. ontheotherhand,iffcissmall,timeresponsewi llbe bad, while it has improved stability, which may cau se overshootorundershootinabnormalcondition. layout consideration a gate drive signal output from gate pin becomes noise source, which may cause malfunction of ic due tocrosstalkifplacedbythesideofananalogli ne.itis recommended to avoid placing the output line especiallybythesideofcs,adim,iset,fsw,ovp, comp,vlspinsasfaraspossible. all the gnd of map3242, agnd, pgnd and lgnd(hsop), are totally seperated internally. for gnd layout, it is the best that all the gnds are seperated to improve noise immunity and avoid unstability.iflayoutdifficultyishigh,theseco ndbestis tyingpgndandlgnd(hsop)andseperatingagnd. followingsaregndlayoutrulesforeachpackage. (1) hsop tiepgnd/lgndandseperateagnd heaksinkpins(hs1,hs2)shoudbetiedtoagnd (2) soic separateagndandpgnd (3) etssop separateagndandpgnd exposed pad shoud be tied to agnd with multiplevias confidential datasheetversion1.1 jun13 th 2013 map3242C4channelleddriverforhighbrightness leds 18 thermal consideration for continuous operation, do not exceed absolute maximum junction temperature. the maximum power dissipationdependsonthethermalresistanceofth eic package, pcb layout, rate of surrounding airflow, a nd difference between junction and ambient temperature . the maximum power dissipation can be calculated by thefollowingformula: ja a max j max t t pd ? = ) ( ) ( wheret j(max) isthemaximumjunctiontemperature,t a is the ambient temperature, and ja is the junction to ambientthermalresistance. the maximum power dissipation depends on the operating ambient temperature for fixed t j(max) and thermal resistance, ja . for the map3242 packages, the derating curve in following graph allows the designertoseetheeffectofrisingambienttemper ature onthemaximumpowerdissipation. foratypicalapplication,theoperationpoweroft heic canbecalculatedroughlyby; pwm fb fb fb fb in in d i v i v i v pd + ? ? ? + + = ) ( ) ( 4 4 1 1 wherev in representstheinputvoltageatthevinpinof the ic and i in represents the current flow into the vin pinoftheic.d pwm isdutycycleofpwminputsignal. confidential datasheetversion1.1 jun13 th 2013 map3242C4channelleddriverforhighbrightness leds 19 physicaldimensions 20leadsetssop symbol dimension min norm max a 1.20 a1 0.00 0.15 a2 0.80 1.05 b 0.19 0.30 c 0.09 0.20 d 6.40 6.60 d1 2.20 e 6.40bsc e1 4.30 4.50 e2 1.50 e 0.65bsc l 0.45 0.75 l1 1.00ref ? 0 8 confidential datasheetversion1.1 jun13 th 2013 map3242C4channelleddriverforhighbrightness leds 20 symbol dimension min norm max a 2.65 a1 0.05 0.30 a2 2.05 2.40 b 0.31 0.51 c 0.20 0.33 d 12.54 13.00 e e1 7.30 7.70 e 1.27bsc l 0.40 1.27 l1 1.40ref ? 0 8 20leadssoic confidential datasheetversion1.1 jun13 th 2013 map3242C4channelleddriverforhighbrightness leds 21 28leadshsop magnachipsemiconductorltd. doesntnotrecommendtheuseofitsproductsinh ostileenvironments,including,withoutlimitation, aircraft,nuclearpowergeneration,medicalapplian ces,anddevicesorsystemsinwhichmalfunctionof anyproductcanreasonably beexpectedtoresultinapersonalinjury.seller scustomersusingorsellingsellersproductsfor useinsuchapplicationsdosoat theirownriskandagreetofullydefendandindemn ifyseller. magnachip reserves the right to change the specifications an dcircuitry without notice at any time. magnachip does not consider responsibilityforuseofanycircuitryotherthan circuitryentirelyincludedina magnachip product. isaregisteredtrademarkofmagnachipsemiconducto rltd. magnachipsemiconductorltd. 891,daechidong,kangnamgu,seo ul,135738korea tel:82269033451/fax:82269033668~9 www.magnachip.com confidential datasheetversion1.1 jun13 th 2013 map3242C4channelleddriverforhighbrightness leds 22 datasheetrevisionhistory date version changes 20120402 version0.0 initialrelease 20120711 version0.1 change:iledmin/maxspec.50ma~200mato90ma~240m page1,4,5,7 change:iledaccuracyconditionspec. i led =100ma,v adim =1.2vtoi led =120ma,v adim =1.2vCpage5 change:adiminputvoltagespec.0.6~2.4vto0.9~2 .4vCpage5,7 change:risetvalue.12kto10kpage7 change:min.ontime(t on_min )spec.15usto30usCpage5 change:softstartscheme(removeovp60%control)C page8,11 addition:abnormalpinvoltageprotectionfunction sCpage4,5 addition:powersequencecommentCpage11 addition:rcssettingdetailguideCpage9 addition:boostmosfetselectionguideCpage12 addition:pcblayoutdetailconsiderationCpage1 3 addition:thermalconsiderationCpage14 20120921 version1.0 |
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