SLUS224F –SEPTEMBER 1994–REVISED OCTOBER …

1 VINUC2843 AVCCVREFRT/CTGNDCOMPFBISENSEOUTPUTC opyright 2017 , Texas Instruments IncorporatedProductFolderOrderNowTechnic alDocumentsTools &SoftwareSupport &CommunityAn IMPORTANTNOTICEat the end of this datasheetaddressesavailability,warranty, changes,use in safety-criticalapplications,intellectual propertymattersand ,UC1843A,UC1844A,UC1845 AUC2842A,UC2843A,UC2844A,UC2845 AUC3842A,UC3843A,UC3844A,UC3845 ASLUS224F SEPTEMBER1994 REVISEDOCTOBER2017 UCx84xACurrent-ModePWM Controller11 Features1 Optimizedfor Off-Lineand DC-DCConverters Low Start-UpCurrent(< mA) TrimmedOscillatorDischargeCurrent AutomaticFeedforwardCompensation Pulse-by-PulseCurrentLimiting EnhancedLoadResponseCharacteristics UndervoltageLockoutWithHysteresis DoublePulseSuppression High-CurrentTotemPoleOutput Internally-TrimmedBandgapReference Up to 500-kHzOperation Createa CustomDesignUsingthe UCx84xAWiththe WEBENCH PowerDesigner2 Applications SwitchModePowerSupplies(SMPS) DC-DCConverters PowerModules IndustrialPSU BatteryOperatedPSU3 DescriptionThe UCx84xAfamilyof controldevicesis a pin-for-pincompatibleimprovedversionof the necessaryfeaturesto controlcurrent-modeor switched-modepowersupplies,this familyofdeviceshas manyimprovedfeatures.

2 Startupcurrentis less mA, oscillatordischargeis mA, and duringUVLO,the outputstagecan sinkat least10 mA at less V for VCCover5 (1)PARTNUMBERPACKAGEBODYSIZE(NOM)UC1842A ,UC1843A,UC1844A,UC1845 ACDIP(8) (20) (20) ,UC2843A,UC2844A,UC2845A,UC3842A,UC3843A ,UC3844A,UC3845 APDIP(8) (8) (14) (16) (1) For all availablepackages,see the orderableaddendumatthe end of the V10 V<100% V<100%UC1844A16 V10 V<50% V<50%SimplifiedApplicationDiagram2UC1842 A,UC1843A,UC1844A,UC1845 AUC2842A,UC2843A,UC2844A,UC2845 AUC3842A,UC3843A,UC3844A,UC3845 ASLUS224F SEPTEMBER1994 :UC1842 AUC1843 AUC1844 AUC1845 AUC2842 AUC2843 AUC2844 AUC2845 AUC3842 AUC3843 AUC3844 AUC3845 ASubmitDocumentationFeedbackCopyright 1994 2017 ,TexasInstrumentsIncorporatedTableof Contents1 Pin Configurationand Applicationand Deviceand Mechanical,Packaging,and ,UC1843A,UC1844A,UC1845 AUC2842A,UC2843A,UC2844A,UC2845 AUC3842A,UC3843A,UC3844A, SEPTEMBER1994 REVISEDOCTOBER2017 ProductFolderLinks:UC1842 AUC1843 AUC1844 AUC1845 AUC2842 AUC2843 AUC2844 AUC2845 AUC3842 AUC3843 AUC3844 AUC3845 ASubmitDocumentationFeedbackCopyright 1994 2017 ,TexasInstrumentsIncorporated4 RevisionHistoryNOTE.

3 Pagenumbersfor previousrevisionsmay differfrompagenumbersin the (October2017)to RevisionFPage AddedWEBENCH linksin threeplaces,Features,Applicationand Implementationand Deviceand Addedcopyrightinformationto the Changedoperatingfree-airtemperatureof the UC284xAchangedfrom125 C to 85 C..6 Changedoperatingfree-airtemperatureof the UC384xAchangedfrom-40 C to 0 C..6 Changedoperatingfree-airtemperatureof the UC384xAchangedfrom85 C to 70 C..6 Changedthe frequency(f) calculationto the Changedthe COUT equationto the Changedthe LPMequationto the AddedGCO(f) definitionand Changedthe fRHPzequationto the (July2011)to RevisionEPage AddedApplicationssection,DeviceInformati ontable,Pin Configurationand Functionssection,Specificationssection,D etailedDescriptionsection,Applicationand Implementationsection,PowerSupplyRecomme ndationssection,Layoutsection,Deviceand DocumentationSupportsection,andMechanica l,Packaging,and DeletedOrderingInformationTable.

4 See POAat the end of the (August2010)to RevisionDPage ChangedAbsoluteMaximumratingstablewith maximumnegativevoltageand GNDpin (September2009)to RevisionCPage to scale4NC5FB6NC7 ISENSE8NC9NC10RT/CT11NC12 PGND13 GND14NC15 OUTPUT16NC17VC18 VCC19NC20 VREF1NC2 COMP3 NCNot to scale1NC16NC2NC15 VREF3 COMP14 VCC4FB13 VCC5 ISENSE12 OUTPUT6RT/CT11 GND7NC10 PGND8NC9 NCNot to scale1 COMP14 VREF2NC13NC3FB12 VCC4NC11VC5 ISENSE10 OUTPUT6NC9 GND7RT/CT8 PGNDNot to scale1 COMP8 VREF2FB7 VCC3 ISENSE6 OUTPUT4RT/CT5 GND4UC1842A,UC1843A,UC1844A,UC1845 AUC2842A,UC2843A,UC2844A,UC2845 AUC3842A,UC3843A,UC3844A,UC3845 ASLUS224F SEPTEMBER1994 :UC1842 AUC1843 AUC1844 AUC1845 AUC2842 AUC2843 AUC2844 AUC2845 AUC3842 AUC3843 AUC3844 AUC3845 ASubmitDocumentationFeedbackCopyright 1994 2017 ,TexasInstrumentsIncorporated5 Pin Configurationand FunctionsCDIP,PDIP,and SOICP ackages8-PinJG, P, and DTop ViewLCCCand PLCCP ackages20-PinFK and FNTop ViewSOICP ackage14-PinDTop ViewSOICP ackage16-PinDWTop View5UC1842A,UC1843A,UC1844A,UC1845 AUC2842A,UC2843A,UC2844A,UC2845 AUC3842A,UC3843A,UC3844A, SEPTEMBER1994 REVISEDOCTOBER2017 ProductFolderLinks.

5 UC1842 AUC1843 AUC1844 AUC1845 AUC2842 AUC2843 AUC2844 AUC2845 AUC3842 AUC3843 AUC3844 AUC3845 ASubmitDocumentationFeedbackCopyright 1994 2017 ,TexasInstrumentsIncorporatedPin (8),PDIP(8),SOIC(8)LCCC(20),PLCC(20)SOIC (14)SOIC(16)COMP1213 OOutputsthe low impedance1-MHzinternalerroramplifierthat is alsothe inputto the peakcurrentlimit or PWMcomparator,with an open-loop gain (AVOL)of 80 dB. This pin is capableof sinkinga maximumof 6 mA and is not the erroramplifierthat can be usedto controlthe powerconvertervoltage-feedbackloop for This is the the peakcurrentlimit,PWMcomparatorof the conjunctionwith a currentsenseresistor,the erroramplifieroutputvoltagecontrolsthe maximumpeakcurrentsensesignalis internallyclampedto 1 V. 1-A totempole pin can sink and sourceup to 1 A of gatedriverresistormustbe usedto limit the 12810 Powergroundand the devicesthat havethispin, star groundingtechniquescan be usedto redirectthe gatedrivercurrentawayfromthe signalgroundpin (GND).

6 Thistechniquecan reducePWMcontrollerinstabilitiescausedby the internaloscillatorthat is programmedwith an externaltimingresistor(RT)and timingcapacitor(CT).SeeOscillatorforinfo rmationon pF to nF. TIalso recommendsthat the timingresistorvalueschosenbe from5 k to 100 k .VC 1711 IBiasinputto the PWMcontrollersthat do not havethis pin, the gatedriveris biasedfromthe VCCpin. This pin musthavea biasingcapacitorthat is at least10 timesgreaterthanthegatecapacitanceof the mainswitchingFET usedin the , 14 IBiasinputto the pin musthavea biasingcapacitorthat is at least10 timesgreaterthanthe gatecapacitanceof themainswitchingFET usedin the the pin mustsupplyno morethan10 mA outputisshort-circuitprotectedat roughly100 mA. This referenceis also usedfor internalcomparatorsand needsa high frequencybypasscapacitorof 1 F. The VCCcapacitoralso mustbe at least10 timesgreaterthanthe capacitoron the 1, 3, 4, 6, 8,9, 11, 14,16, 192, 4, 6, 131, 2, 7, 8,9, 16 No connection6UC1842A,UC1843A,UC1844A,UC184 5 AUC2842A,UC2843A,UC2844A,UC2845 AUC3842A,UC3843A,UC3844A,UC3845 ASLUS224F SEPTEMBER1994 :UC1842 AUC1843 AUC1844 AUC1845 AUC2842 AUC2843 AUC2844 AUC2845 AUC3842 AUC3843 AUC3844 AUC3845 ASubmitDocumentationFeedbackCopyright 1994 2017 ,TexasInstrumentsIncorporated(1)Stre ssesbeyondthoselistedunderAbsoluteMaximu mRatingsmay causepermanentdamageto the stressratingsonly,whichdo not implyfunctionaloperationof the deviceat theseor any otherconditionsbeyondthoseindicatedunder RecommendedOperatingConditions.

7 Exposureto absolute-maximum-ratedconditionsfor extendedperiodsmay (unlessotherwisenoted)(1)MINMAXUNITS upplyvoltage(low impedancesource)VCCpin30 VOutputcurrent,IOUT 1 AOutputenergy(capacitiveload)5 JAnaloginputs pins and VCCVC pin current,ICOMP10mAPowerdissipationat TA 25 C1 WLeadtemperature(soldering,10 s)300 CJunctiontemperature,TJ 55150 CStoragetemperature,Tstg 65150 C(1)JEDEC documentJEP155statesthat 500-VHBM allowssafe manufacturingwith a standardESDcontrolprocess.(2)JEDEC documentJEP157statesthat 250-VCDM allowssafe manufacturingwith a (ESD)ElectrostaticdischargeHuman-bodymod el(HBM),per ANSI/ESDA/JEDECJS-001(1) 2000 VCharged-devicemodel(CDM),per JEDEC specificationJESD22-C101(2) (unlessotherwisenoted)MINNOMMAXUNITVCCB iassupplyvoltageVCCpin11 VVFB, VRC, VVFBV oltageon analogpinsFB, ISENSE,and RT/CTpins current25mAIVREFO utputcurrentVREFpin10mAfOSCO scillatorfrequency500kHzTAOperatingfree- airtemperatureUC184xA 55125 CUC284xA 4085UC384xA0707UC1842A,UC1843A,UC1844A,U C1845 AUC2842A,UC2843A,UC2844A,UC2845 AUC3842A,UC3843A,UC3844A, SEPTEMBER1994 REVISEDOCTOBER2017 ProductFolderLinks.

8 UC1842 AUC1843 AUC1844 AUC1845 AUC2842 AUC2843 AUC2844 AUC2845 AUC3842 AUC3843 AUC3844 AUC3845 ASubmitDocumentationFeedbackCopyright 1994 2017 ,TexasInstrumentsIncorporated(1)For moreinformationabouttraditionaland new thermalmetrics,see theSemiconductorand IC (1)UC184xAUC2843 AUC284xA,UC384xAUNITJG (CDIP)FK (LCCC)FN (PLCC)P (PDIP)D (SOIC)D (SOIC)DW (SOIC)8 PINS20 PINS20 PINS8 PINS8 PINS14 PINS16 PINSR JAJunction-to-ambientthermalresistance C/WR JC(top)Junction-to-case(top) C/WR C/W JTJunction-to-topcharacterizationparamet er C/W JBJunction-to-boardcharacterizationparam eter C/WR JC(bot)Junction-to-case(bottom) C/W(1)AdjustVCCabovethe startthresholdbeforesettingat 15 V.(2)Ensuredby design,but not 100%productiontested.(3)Temperaturestabi lity,sometimesreferredto asaveragetemperaturecoefficient, is describedby: Temperaturestability= ( VREF(max) VREF(min)) / (TJ(max) TJ(min)).

9 VREF(max)and VREF(min)are the maximumand minimumreferencevoltagemeasuredoverthe the extremesin voltagedo not necessarilyoccurat the extremesin temperature.(4)Outputfrequencyequalsosci llatorfrequencyfor the UC1842 Aand one half oscillatorfrequencyfor theUC1844 Aand UC1845A.(5)This parameteris measuredwith RT= 10 k to VREF. This contributesapproximately300 A of currentto the totalcurrentflowinginto the RT/CTpin is approximately300 A higherthanthe ,thesespecificationsapplyfor TA= 55 C to 125 C (UC184xA),TA= 40 C to 125 C (UC284xAQ),TA= 40 C to 85 C (UC284xA),TA= 0 C to 70 C (UC384xA);TA= TJ; VCC= 15 V(1); RT= 10 k ; CT= 25 C, IO= 1 mAUC184xA, regulation12 VIN 25 V620mVLoadregulation1 IO 20 mA625mVTemperaturestabilitySee(2)(3) CTotaloutputvariationLine,Load,Temperatu reUC184xA, Hz f 10 kHz;TJ= 25 C(2)50 VLong-termstabilityTA= 125 C, 1000hrs(2)525mVOutputshortcircuit 30 100 180mAOSCILLATORI nitialaccuracyTJ= 25 C(4)475257kHzVoltagestability12 VCC 25 TA TMAX(2)5%AmplitudeVRT/CTpeakto peak(2) 25 C, VRT/CT= 2 V(5) 2 V(5)UC184xA, ,UC1843A,UC1844A,UC1845 AUC2842A,UC2843A,UC2844A,UC2845 AUC3842A,UC3843A,UC3844A,UC3845 ASLUS224F SEPTEMBER1994 :UC1842 AUC1843 AUC1844 AUC1845 AUC2842 AUC2843 AUC2844 AUC2845 AUC3842 AUC3843 AUC3844 AUC3845 ASubmitDocumentationFeedbackCopyright 1994 2017 ,TexasInstrumentsIncorporatedElectri calCharacteristics(continued)Unlessother wisestated,thesespecificationsapplyfor TA= 55 C to 125 C (UC184xA),TA= 40 C to 125 C (UC284xAQ),TA= 40 C to 85 C (UC284xA),TA= 0 C to 70 C (UC384xA);TA= TJ; VCC= 15 V(1); RT= 10 k ; CT= (6)Parametermeasuredat trip pointof latchwith VFB= 0.

10 (7)Gaindefinedas: A = VCOMP/ VISENSE; 0 VISENSE VUC184xA, current 1 A 2 AVOLOpen-loopgain2 VO 4 V6590dBUnitygain bandwidthTJ= 25 C(2) VCC 25 V6070dBOutputsink currentVFB= V, VCOMP= V26mAOutputsourcecurrentVFB= V, VCOMP= 5 V V, RL= 15 k to ground56 VVOUTlowVFB= V, RL= 15 k to (6)(7) 5 V(6) VCC25 V(6)70dBInputbias current 2 10 ADelayto outputVISENSE= 0 to 2 V(2)150300nsOUTPUTO utputlow levelISINK= 20 200 levelISOURCE= 20 200 25 C, CL= 1 nF(2)50150nsFall timeTJ= 25 C, CL= 1 nF(2)50150nsUVLO saturationVCC= 5 V, ISINK= 10 ,UC1844A,UC2842A,and UC2844A151617 VUC3842 Aand ,UC1844A,UC2842A,and UC2844A91011 VUC3842 Aand cycleUCx842A,UCx843A94%96%100%UCx844A,UC x845A47%48%50%Minimumduty cycle0% VISENSE= 0 V1117mAVCCZ enervoltageICC= 25 mA3034V9UC1842A,UC1843A,UC1844A,UC1845 AUC2842A,UC2843A,UC2844A,UC2845 AUC3842A,UC3843A,UC3844A, SEPTEMBER1994 REVISEDOCTOBER2017 ProductFolderLinks:UC1842 AUC1843 AUC1844 AUC1845 AUC2842 AUC2843 AUC2844 AUC2845 AUC3842 AUC3843 AUC3844 AUC3845 ASubmitDocumentationFeedbackCopyright 1994 2017 , OutputSaturationCharacteristicsFigure2.