approximatelystatusmonitor

LTC442514425fTYPICALAPPLICATIONFEATURESDESCRIPTIONLinearSuperCapChargerwithCurrent-LimitedIdealDiodeandV/IMonitorTheLTC4425isaconstant-current/constant-voltagelinearchargerdesignedtochargea2-cellsupercapstackfromeitheraLi-Ion/Polymerbattery,aUSBport,ora2.
7Vto5.
5Vcurrent-limitedsupply.
Thepartoperatesasanidealdiodewithanextremelylow50mΩon-resistancemakingitsuitableforhighpeak-power/lowaveragepowerapplications.
TheLTC4425chargestheoutputcapacitorstoanexternallyprogrammedoutputvoltageinLDOmodeataconstantchargecurrent,ortoVINinnormalmodewithasmartchargecurrentproletolimittheinrushcurrentuntiltheVINtoVOUTdifferentialislessthan250mV.
InadditiontheLTC4425canbesettoclamptheoutputvoltageto4.
9Vor5.
4V.
Chargecurrent(VOUTcurrentlimit)isprogrammedbyconnectingaresistorbetweenPROGandGND.
ThevoltageonthePROGpinrepresentsthecurrentowingfromVINtoVOUTforcurrentmonitoring.
Aninternalactivebalancingcircuitmaintainsequalvoltagesacrosseachsupercapacitorandclampsthepeakvoltageacrosseachcelltoapin-selectablemaximumvalue.
TheLTC4425operatesataverylow20μAquiescentcurrent(shutdowncurrent750mV20.
2AARPROG=5k,VIN–VOUT750mV20020mAmAVPROGPROGPinServoVoltageinLDOModeFB750mV1.
000.
1VVISCChargerShort-CircuitCurrentLimitPROGPinShortedtoGND,FB=0234AtSSChargerSoftStartTimeFB=01.
5msTLIMJunctionTemperatureinConstantTemperatureMode(Note5)VOUT=0,FB=0,RPROG=0.
5k105°CVoltageClampsVCLAMPMaximumVoltageAcrosstheTopCapacitorVSEL=LoVSEL=Hill2.
452.
72.
52.
75VVMaximumVoltageAcrosstheBottomCapacitorVSEL=LoVSEL=Hill2.
452.
72.
52.
75VVVRIPVOUTClampHysteresisIfEitherCapacitorReachesClampVoltagei.
e.
VOUTVCLAMP160mAISH(BOT)BottomShuntCurrentRPROG=1k,VMID>VCLAMP140mALTC442544425fNote1:StressesbeyondthoselistedunderAbsoluteMaximumRatingsmaycausepermanentdamagetothedevice.
ExposuretoanyAbsoluteMaximumRatingconditionforextendedperiodsmayaffectdevicereliabilityandlifetime.
Note2:ThecurrentlimitfeaturesofthispartareintendedtoprotecttheICfromshorttermorintermittentfaultconditions.
Continuousoperationabovethemaximumspeciedpincurrentratingmayresultindevicedegradationorfailure.
Note3:FailuretosoldertheexposedbacksideofthepackagetothePCboardgroundplanewillresultinathermalresistancemuchgreaterthan43°C/WontheDDpackageandgreaterthan35°C/WonMSEpackage.
Note4:TheLTC4425E(Egrade)isguaranteedtomeetspecicationsfrom0°Cto85°Cjunctiontemperature.
Specicationsoverthe–40°Cto125°Coperatingjunctiontemperaturerangeareassuredbydesign,characterizationandcorrelationwithstatisticalprocesscontrols.
TheLTC4425I(Igrade)isguaranteedoverthefull–40°Cto125°Coperatingjunctiontemperaturerange.
Thejunctiontemperature,TJ,iscalculatedfromtheambienttemperature,TA,andpowerdissipation,PD,accordingtotheformula:TJ=TA+(PDθJA°C/W).
Notethatthemaximumambienttemperatureisdeterminedbyspecicoperatingconditionsinconjunctionwithboardlayout,theratedthermalpackagethermalresistanceandotherenvironmentalfactors.
Note5:VINtoVOUTchargecurrentisreducedbythermalfoldbackasjunctiontemperatureapproaches105°C.
ELECTRICALCHARACTERISTICSTheldenotesthespecicationswhichapplyoverthefulloperatingjunctiontemperaturerange,otherwisespecicationsareatTA=25°C,VIN=3.
8V.
(Note4)SYMBOLPARAMETERCONDITIONSMINTYPMAXUNITSLeakageBalancerVMIDVMIDOutputVoltageVOUT=3.
6V1.
761.
81.
84VVMIDMaximumCurrentSourcingCapabilityVMIDVOUT/2,VMIDVINOperationIftheENpinispulledhighandVINisbelowVOUToroating,mostofthecircuitryincludingthevoltageclampcircuitryiskeptaliveandthepartdrawsabout20μAfromtheoutputcapacitors.
However,theinternalleakagebalanceristurnedoffunderthiscondition.
ShutdownModeTheLTC4425canbeshutdownbypullingtheENpinlow.
Inshutdownmode,veryminimalcircuitryisaliveandthepartdrawslessthan3μAfromthesupplyorfromtheoutputcapacitorsifthesupplyisnotpresent.
ChargeCurrentSoft-StartTheLTC4425includesasoft-startcircuittominimizetheinrushcurrentatthestartofachargecycle.
Whenachargecycleisinitiated,thechargecurrentrampsfromzerotofull-scaleoveraperiodofapproximately1msandthissoft-startcanbemonitoredbyobservingthePROGpinvoltage.
Thishastheeffectofminimizingthetransientcurrentloadonthepowersupplyduringstart-up.
ThermalShutdownTheLTC4425includesathermalshutdowncircuitinad-ditiontothethermalregulator.
Ifforanyreason,thedietemperatureexceeds160°C,theentirepartshutsdown.
Itresumesnormaloperationoncethetemperaturedropsbyabout14°C,toapproximately146°C.
LTC4425124425fProgrammingtheOutputVoltageInLDOmode,theLTC4425outputvoltagecanbepro-grammedforanyvoltagebetween2.
7VandVINbyusingaresistordividerfromVOUTpintoGNDviatheFBpinsuchthat:VOUT=VFB(1+RFB1/RFB2)whereVFBis1.
2V.
SeeFigure3.
TypicalvaluesforRFBareintherangeof40kto1M.
ToosmallaresistorwillresultinalargequiescentcurrentwhereastoolargearesistorcoupledwithFBpincapaci-tancewillcreateanadditionalpoleandmaycauseloopinstability.
APPLICATIONSINFORMATIONPROGpin.
Theprogramresistorandthechargecurrentarecalculatedusingthefollowingequations:RPROG=1000(1V/ICHRG),ICHRG=1000(1V/RPROG)whereICHRGisthechargecurrentoutoftheVOUTpin.
ThechargecurrentoutoftheVOUTpincanbedeterminedatanytimebymonitoringthePROGpinvoltageandusingthefollowingequation:ICHRG=1000(VPROG/RPROG)StabilityConsiderationsInLDOmode,theLTC4425supercapacitorchargerhastwoprincipalcontrolloops:constant-voltageandconstant-current.
Theconstant-voltageloopisstablewhenconnectedtoasupercapofatleast0.
2F.
However,whendisconnectedfromthesupercap,thevoltagelooprequiresatleast10μFcapacitanceinserieswith500Ωresistanceforstability.
Inconstant-currentmode,thePROGpinvoltageisinthefeedbackloop,nottheVOUTpinvoltage.
BecauseoftheadditionalpolecreatedbythePROGpincapacitance,capacitanceonthispinmustbekepttoaminimum.
WithnoadditionalcapacitanceonthePROGpin,thechargerisstablewithaprogramresistorashighas100k.
However,anyadditionalcapacitanceonthisnodereducesthemaximumallowedprogramresistor.
ThepolefrequencyatthePROGpinshouldbekeptabove100kHz.
Therefore,ifthePROGpinisloadedwithacapacitance,CPROG,thefollowingequationshouldbeusedtocalculatethemaximumresistancevalueforRPROG:RPROG≤1/(2π100kHzCPROG)BoardLayoutConsiderationsTobeabletodelivermaximumchargecurrentunderallconditions,itiscriticalthattheexposedmetalpadonthebacksideoftheLTC4425'stwopackageshaveagoodthermalcontacttothePCboardground.
Correctlysolderedtoa2500mm2double-sided1oz.
copperboard,theDFNpackagehasathermalresistanceofapproximately43°C/W.
Failuretomakethermalcontactbetweentheexposedpadonthebacksideofthepackageandthecopperboardwillresultinathermalresistancefargreaterthan43°C/W.
4425F03LTC4425PFIFBPFI_RETRPF1RPF2RFB1RFB2VINVINVOUTVOUTFigure3.
ProgrammingOutputVoltageandInputThresholdforPowerFailComparator.
ProgrammingtheInputVoltageThresholdforPowerFailStatusIndicatorTheinputvoltagebelowwhichthepowerfailstatuspinPFOindicatesapower-failconditionisprogrammedbyusingaresistordividerfromtheVINpintothePFI_RETpinviathePFIpinsuchthat:VIN,PFO=VPFI(1+RPF1/RPF2)whereVPFIis1.
2V.
SeeFigure3.
TypicalvaluesforRPFareintherangeof40kto1M.
Inshutdownmode,thisdividernetworkisdisconnectedfromgroundviathePFI_RETpintosavethequiescentcurrentdrawnbythenetwork.
ProgrammingtheChargeCurrentTheLTC4425chargecurrentisprogrammedusingasingleresistorfromthePROGpintoground.
ThechargecurrentoutoftheVOUTpinis1000timesthecurrentoutoftheLTC4425134425fChargeCurrentReductionbytheThermalRegulatorToprotectthepartagainstexcessiveheatgeneratedbyinternalpowerdissipation,theLTC4425isequippedwithathermalregulatorwhichautomaticallyreducesthechargecurrenttomaintainamaximumdietemperatureof105°C.
Ignoringthequiescentcurrent,thepowerdissipationcanbeapproximatedbythefollowingequation:PD=(VIN–VOUT)ICHRGIfθJAisthethermalresistanceandTAistheambienttemperature,thenthedietemperaturecanbecalculatedas:TDIE=TA+PDθJAWhenthepartisinthermalregulation,thedietemperatureis105°CandforagivenVINandVOUT,thechargecurrentcanbedeterminedbythefollowingequation:ITVVCHRGAINOUTJA=()105––θForexample,iftheLTC4425intheDFNpackageisusedinLDOmodetochargeacompletelydischargedsupercapstack(VOUT=0V)ataroomtemperatureof25°Cfroma5Vsource,thechargecurrent,atrst,willbelimitedtoapproximately:ICCVCWCCAmACHRG=°°()°=°°=10525504380215372––//Astheoutputvoltagerises,thechargecurrentwillgraduallyrisetothefullchargecurrentprogrammedbythePROGpinresistoraslongastheconstant-currentloopisincontrol.
IftheLTC4425isprogrammedforachargecurrentof2A,theoutputvoltageatwhichthepartwilldeliverfullchargecurrentcanbedeterminedbythefollowingequation:VVTIOUTINACHRGJA=––105θUsingthepreviousexample,forfullchargecurrent,theoutputvoltagehastorisetoatleast:VVCACWVCCVVOUT=()°°=°°=51052524358086407––/–/.
APPLICATIONSINFORMATIONFigure4showsthegraphofchargecurrentvsoutputvoltagewhenthechargecurrentproleisturnedoffbyshortingtheFBpintoGNDandthechargecurrentislimitedbythermalregulation.
OUTPUTVOLTAGE(V)00CHARGECURRENT(A)2.
01.
51.
00.
52.
51562344425F04VIN=5VRPROG=500ΩTA=25°CFBPINGROUNDEDTHERMALREGULATION4.
07V≈105°C372mAFigure4.
ChargeCurrentvsOutputVoltageunderThermalRegulation(LDOMode)C1CSUPVOUTC1=C2≥100μFC24425F05LTC4425VOUTVMIDGNDFigure5.
ChargingaSingleSupercapacitorChargingaSingleSupercapacitorTheLTC4425canalsobeusedtochargeasinglesuper-capacitorbyconnectingtwoseries-connectedmatchedceramiccapacitorswithaminimumcapacitanceof100μFinparallelwiththesupercapacitorasshowninFigure5.
RefertoTable1forsupercapacitormanufacturers.
Table1.
SupercapacitorManufacturersCAP-XXwww.
cap-xx.
comNESSCAPwww.
nesscap.
comMaxwellwww.
maxwell.
comBussmannwww.
cooperbussmann.
comAVXwww.
avx.
comIllinoisCapacitorwww.
illcap.
comTecateGroupwww.
tecategroup.
comLTC4425144425fTYPICALAPPLICATIONSUSBtoHighPeakPower3.
3VCharging3*AAAlkalinetoHighPeakPower3.
3VChargingVOUTVMIDFBPROGPFO3.
3VTOLOAD2.
1M2.
2μF1.
2M2k470k1F1FVIOLTC4425ENSELPFI_RETPFIVIN5V,500mAUSB1.
5M1.
2M4425TA03μCVOUTVMIDFBPROGPFO3.
3V,2ATOLOADCURRENTMONITOR2.
1M1.
2M500Ω470k1F1FLTC4425ENSELPFI_RETPFIVIN4.
5VTO3.
6V1.
5M1.
2M3sAA4425TA04μCVIO2.
2μFLi-IonHighPeakPowerBatteryBufferVOUTVMIDPROGPFOTOLOADCURRENTMONITOR0.
6F0.
6FLTC4425FBPFIPFI-RETENLi-Ion1.
5M500Ω1.
2M470kSELVIN4425TA04a+VIO2.
2μFLTC4425154425fTYPICALAPPLICATIONSUSBC110μF0805R1100kμCVBUSD0D1D2NTCCHRGCLPROGPROGGNDBATGATELDO3V3VOUTC/XSWLTC4088L13.
3μHM1+LI-IonR42kR32.
94kC20.
1μF0603R58.
2ΩR2100kL1:COILCRAFTLPS4018-332MLCM1:SILICONIXSi2333R2:VISHAY-DALENTHS0603N011-N1003FC1,C3:MURATAGRM21BR61A106KE19C2:MURATAGRM188R71C104KA01CSC:CAP-XXHS203FINSTANT-ONCSC0.
55FHS203FVOUTVINPFISELENPFOPFI_RETVMIDVINFBPROGGNDR62kμCR81.
2MR71.
5MLTC44254425TA05C310μF08055VVINLOADHighCurrentUSBChargingwithPowerPathControl3.
3VPeak-Power/Back-upSupplyCSC0.
55FHS203FVOUTVINPFISELENPFOPFI_RETVMIDVINFBPROGGND2kμC1.
2M1.
5MLTC44254425TA05aSW1PVINVINRUN/SSRTSW2PVOUTVOUTFBLTC353310μF5VVIN≈5V340k6.
49k100μF47pFVOUT3.
3V1.
5A200k0.
1μF107k330pF4.
7pF2.
2μH33.
2k200kPGNDSGNDONOFFBURSTVC2.
2μFLTC4425164425fLTC4425VINFBPFISELENPFOPFI_RETVOUTVMIDPROGGNDCSP11FCSP21FμCR81.
2M1.
5M11kR62kVOUTSWISENSEFBILIMVIN59k28.
7kGND2.
2μFLT3663RUNBOOSTOFFON0.
1μFD122μF5VINSTANT-ON6.
8μHD1:DFLS240CSP1,CSP2:12V4425TA075VHIGH-PEAKPOWER,ORBACKUPSUPPLY12VInputto5VOutputswithInputVoltageMonitoringTYPICALAPPLICATIONSCSP11FCSP21F3.
3V5VVOUTVINVOUT(5V)VINSHDNRTGNDVCFBSWBOOSTPFISELENPFOPFI_RETVMIDFBPROGGNDR62k1.
2M2.
1MμCR81.
2MR71.
5MLTC4425LT35054425TA0612V10μF68pF11.
3k61.
1k10μH0.
1μFD1D269.
8k75k70pF1μFD1:1N4148D2:MBRM140CSP1,CSP2:CAP-XXHS203FHIGHPEAK-POWERLOAD12Vto5V/3.
3VHighPeakPowerSupplyLTC4425174425fTYPICALAPPLICATIONSRedundantHighPeakPowerBatterySuppliesLTC4425LTC4425SELENPFOPFOFBPFIPFI_RETVINSELENFBPFIPFI_RETVINVOUTVMIDVOUTVIOVMID1.
2M1.
5M2.
2μFPROGPROG2k500Ω470k1.
5M3sAA1.
2M4425TA08USBTOLOADBATPOWEROKUSBPOWEROK1F1FμC2.
2μFLTC4425184425fPACKAGEDESCRIPTION3.
00±0.
10(4SIDES)NOTE:1.
DRAWINGISNOTAJEDECPACKAGEOUTLINE2.
DRAWINGNOTTOSCALE3.
ALLDIMENSIONSAREINMILLIMETERS4.
DIMENSIONSOFEXPOSEDPADONBOTTOMOFPACKAGEDONOTINCLUDEMOLDFLASH.
MOLDFLASH,IFPRESENT,SHALLNOTEXCEED0.
15mmONANYSIDE5.
EXPOSEDPADANDTIEBARSSHALLBESOLDERPLATED6.
SHADEDAREAISONLYAREFERENCEFORPIN1LOCATIONONTHETOPANDBOTTOMOFPACKAGE0.
40±0.
10BOTTOMVIEW—EXPOSEDPAD1.
65±0.
100.
75±0.
05R=0.
115TYP16127PIN1TOPMARK(SEENOTE6)0.
200REF0.
00–0.
05(DD12)DFN0106REVARECOMMENDEDSOLDERPADPITCHANDDIMENSIONSAPPLYSOLDERMASKTOAREASTHATARENOTSOLDERED0.
23±0.
050.
25±0.
052.
25REF2.
38±0.
051.
65±0.
052.
10±0.
050.
70±0.
053.
50±0.
05PACKAGEOUTLINEPIN1NOTCHR=0.
20OR0.
25s45°CHAMFER2.
38±0.
102.
25REF0.
45BSC0.
45BSCDDPackage12-LeadPlasticDFN(3mm*3mm)(ReferenceLTCDWG#05-08-1725RevA)LTC4425194425fInformationfurnishedbyLinearTechnologyCorporationisbelievedtobeaccurateandreliable.
However,noresponsibilityisassumedforitsuse.
LinearTechnologyCorporationmakesnorepresenta-tionthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights.
MSOP(MSE12)0608REVB0.
53±0.
152(.
021±.
006)SEATINGPLANE0.
18(.
007)1.
10(.
043)MAX0.
22–0.
38(.
009–.
015)TYP0.
86(.
034)REF0.
650(.
0256)BSC121211109877DETAIL"B"16NOTE:1.
DIMENSIONSINMILLIMETER/(INCH)2.
DRAWINGNOTTOSCALE3.
DIMENSIONDOESNOTINCLUDEMOLDFLASH,PROTRUSIONSORGATEBURRS.
MOLDFLASH,PROTRUSIONSORGATEBURRSSHALLNOTEXCEED0.
152mm(.
006")PERSIDE4.
DIMENSIONDOESNOTINCLUDEINTERLEADFLASHORPROTRUSIONS.
INTERLEADFLASHORPROTRUSIONSSHALLNOTEXCEED0.
152mm(.
006")PERSIDE5.
LEADCOPLANARITY(BOTTOMOFLEADSAFTERFORMING)SHALLBE0.
102mm(.
004")MAX0.
254(.
010)0°–6°TYPDETAIL"A"DETAIL"A"GAUGEPLANERECOMMENDEDSOLDERPADLAYOUTBOTTOMVIEWOFEXPOSEDPADOPTION2.
845±0.
102(.
112±.
004)2.
845±0.
102(.
112±.
004)4.
039±0.
102(.
159±.
004)(NOTE3)1.
651±0.
102(.
065±.
004)0.
1016±0.
0508(.
004±.
002)1234563.
00±0.
102(.
118±.
004)(NOTE4)0.
406±0.
076(.
016±.
003)REF4.
90±0.
152(.
193±.
006)MSEPackage12-LeadPlasticMSOP,ExposedDiePad(ReferenceLTCDWG#05-08-1666RevB)DETAIL"B"CORNERTAILISPARTOFTHELEADFRAMEFEATURE.
FORREFERENCEONLYNOMEASUREMENTPURPOSE0.
12REF0.
35REF5.
23(.
206)MIN3.
20–3.
45(.
126–.
136)0.
889±0.
127(.
035±.
005)0.
42±0.
038(.
0165±.
0015)TYP0.
65(.
0256)BSCPACKAGEDESCRIPTIONLTC4425204425fLinearTechnologyCorporation1630McCarthyBlvd.
,Milpitas,CA95035-7417(408)432-1900FAX:(408)434-0507www.
linear.
comLINEARTECHNOLOGYCORPORATION2010LT0510PRINTEDINUSARELATEDPARTSPARTNUMBERDESCRIPTIONCOMMENTSLTC3225-1LTC3225150mASupercapacitorChargerProgrammableSupercapacitorChargerDesignedtoChargeTwoSupercapacitorsinSeriestoaFixedOutputVoltage(4.
8V/5/3VSelectable)LT3485-0/LT3485-1/LT3485-2/LT3485-31.
4A/0.
7A/1A/2APhotoashCapacitorChargerwithOutputVoltageMonitorandIGBTVIN;1.
8Vto10V,ChargeTime=3.
7SecondsfortheLT3485-0(0Vto320V,100μF,VIN=3.
6V),ISD<1μA,3mm*3mm10-LeadDFNLT3750CapacitorChargerControllerChargesAnySizeCapacitor,10-LeadMSPackageLT3751CapacitorControllerwithRegulationChargesAnySizeCapacitor,4mm*5mmQFN-20PackageTYPICALAPPLICATIONLTC4425LTC3569(UDPACKAGE)VINFBPFISELENPFOPFI_RETVOUTVOUT(5V)VMIDPROGGNDCSP11FCSP21F846μC11,12R71.
5MR81.
2M957313101,25V,2AR6500ΩSVINPVIN,1,2,3SW1PGND,1,2,3SGNDSW2SW3PGOODFB1FB2FB3L22.
2μH10μF20pF750k240kSWBIASFBVCPGRTVINBD10μF200k28.
7kL12.
2μH22μF590k20kGND2.
2μFLT3684RUNBOOST3.
3VL32.
5μH4.
7μF20pF300k240k1.
8VL42.
5μH4.
7μF20pF150k240k1.
2VOFFONCARBATTERYD1330pF6Vto36V0.
1μFEN1EN2EN3MODERTD1:DIODESINC.
DFLS240L1:SUMIDACDRH4D22/HP-2R2L2:WURTH7440430022L3,L4WURTH744031002CSP1,CSP2:CAP-XXHS203F4425TA09EmbeddedAutomotiveBackupController