LM4880 Dual 250 mW Audio Power Amplifier with …

1 NOVEMBER1995 REVISEDMAY2013LM4880 Dual250mWAudioPowerAmplifierwithShutdown ModeCheckforSamples:LM48801 FEATURESDESCRIPTIONTheLM4880is a dualaudiopoweramplifiercapable2 NoBootstrapCapacitorsorSnubberCircuitsof deliveringtypically250mWperchannelofareN ecessarycontinuousaveragepowertoan8 SmallOutline(SOIC)andPDIPP ackagingTHD+Nusinga 5 Vpowersupply. Unity-GainStableBoomeraudiopoweramplifie rsweredesigned ExternalGainConfigurationCapabilityspeci ficallytoprovidehighqualityoutputpowerwi thaminimalamountofexternalcomponentsusin gAPPLICATIONS surfacemountpackaging.

2 HeadphoneAmplifierSincetheLM4880doesnotr equirebootstrapcapacitorsorsnubbernetwor ks,it isoptimallysuited PersonalComputersforlow-powerportablesys tems. CD-ROMP layersTheLM4880featuresanexternallycontr olled,low-powerconsumptionshutdownmode,a swellasanKEYSPECIFICATIONS internalthermalshutdownprotectionmechani sm. THD+Nat1kHzat200mWContinuousAverageTheun ity-gainstableLM4880canbeconfiguredbyOut putPowerinto8 : (max)externalgain-settingresistors. THD+Nat1kHzat85mWContinuousAverageOutput Powerinto32 : (typ) OutputPowerat10%THD+Nat1kHzinto8 325mW(typ) A (typ) ,standardwarranty,andusein 1995 2013, NOVEMBER1995 * (1)(2) 65 C to+150 CInputVoltage + (3)InternallylimitedESDS usceptibility(4)2000 VESDS usceptibility(5)200 VJunctionTemperature150 CSolderingInformationSmallOutlinePackage VaporPhase(60sec.)

3 215 CInfrared(15sec.)220 CThermalResistance JC(PDIP)37 C/W JA(PDIP)107 C/W JC(SOIC)35 C/W JA(SOIC)170 C/W(1) functional, given,however,thetypicalvalueis a goodindicationofdeviceperformance.(2)If Military/Aerospacespecifieddevicesarereq uired,pleasecontacttheTexasInstrumentsSa lesOffice/Distributorsforavailabilityand specifications.(3)Themaximumpowerdissipa tionmustbederatedatelevatedtemperaturesa ndis dictatedbyTJMAX, JA, andtheambienttemperatureTA. Themaximumallowablepowerdissipationis PDMAX= (TJMAX TA)/ JAorthenumbergivenin theAbsoluteMaximumRatings,whicheveris ,TJMAX= 150 C,andthetypicaljunction-to-ambienttherma lresistanceis 170 C/WforpackageD0008 Aand107 C/WforpackageP0008E.

4 (4)Humanbodymodel,100pFdischargedthrough a resistor.(5)Machinemodel,220pF 1995 2013, NOVEMBER1995 REVISEDMAY2013 OperatingRatingsTemperatureRangeTMIN TA TMAX 40 C TA +85 VDD (1)(2)Thefollowingspecificationsapplyfor VDD= 25 (Limits)TypicalLimit(3)(4) (min) (max)IDDQ uiescentPowerSupplyCurrentVIN=0V,IO= (max)ISDS hutdownCurrentVPIN5= A (max)VOSO utputOffsetVoltageVIN=0V550mV(max)POOutp utPowerTHD= (max);f=1kHz;RL=8 250200mW(min)RL=32 85mWTHD+N=10%;f=1kHzRL=8 325mWRL=32 110mWTHD+NTotalHarmonicDistortion+NoiseR L=8 , PO=200mW; , PO=75mW.

5 F,50dBVRIPPLE=200mVrms,f = 100Hz(1)Allvoltagesaremeasuredwithrespec ttothegroundpin,unlessotherwisespecified .(2) functional, given,however,thetypicalvalueis a goodindicationofdeviceperformance.(3)Typ icalsaremeasuredat25 C andrepresenttheparametricnorm.(4)Limitsa reensuredtoTI's AOQL(AverageOutgoingQualityLevel). 1995 2013,TexasInstrumentsIncorporatedSubmitD ocumentationFeedback3 ProductFolderLinks:LM4880LM4880 SNAS103C NOVEMBER1995 (Figure2) conjunctionwithRF. Thisresistoralsoformsa highpassfilterwithCiatfc= 1/(2 RiCi).

6 ' highpassfilterwithRiatfc= 1/(2 RiCi). ' highpassfilterwithRLatfo= 1/(2 RLCo).4 SubmitDocumentationFeedbackCopyright 1995 2013, NOVEMBER1995 REVISEDMAY2013 TypicalPerformanceCharacteristicsTHD+ NTHD+ + NTHD+ + NTHD+ 1995 2013,TexasInstrumentsIncorporatedSubmitD ocumentationFeedback5 ProductFolderLinks:LM4880LM4880 SNAS103C NOVEMBER1995 (continued)THD+ NTHD+ + NTHD+ 1995 2013, NOVEMBER1995 REVISEDMAY2013 TypicalPerformanceCharacteristics(contin ued) 1995 2013,TexasInstrumentsIncorporatedSubmitD ocumentationFeedback7 ProductFolderLinks.

7 LM4880LM4880 SNAS103C NOVEMBER1995 (continued) 1995 2013, NOVEMBER1995 REVISEDMAY2013 TypicalPerformanceCharacteristics(contin ued) 1995 2013,TexasInstrumentsIncorporatedSubmitD ocumentationFeedback9 ProductFolderLinks:LM4880LM4880 SNAS103C NOVEMBER1995 use,theLM4880containsa shutdownpintoexternallyturnofftheamplifi er' logiclowandlogichighlevelis is ,theLM4880supplycurrentdrawwillbeminimiz edin , ,theshutdownpinshouldbetiedtoa ,a microcontrollerormicroprocessoroutputis usedtocontroltheshutdowncircuitrywhichpr ovidesa quick, tousea single-pole, closed,theshutdownpinis theswitchis open.

8 Majorconcernwhenusinganypoweramplifieran dmustbethoroughlyunderstoodtoensurea statesthemaximumpowerdissipationpointfor a single-endedamplifieroperatingata givensupplyvoltageanddrivinga (VDD)2/(2 2RL)(1)SincetheLM4880hastwooperationalam plifiersinonepackage,themaximuminternalp owerdissipationpointistwicethatofthenumb erwhichresultsfromEquation1. Evenwiththelargeinternalpowerdissipation ,theLM4880doesnotrequireheatsinkingovera , assuminga5 Vpowersupplyandan8 load, :PDMAX= (TJMAX-TA)/ JA(2)FortheLM4880surfacemountpackage, JA=170 C/WandTJMAX=150 ,TA, ofthesystemsurroundings,Equation2 theresultofEquation1 isgreaterthanthatofEquation2, theneitherthesupplyvoltagemustbedecrease d,theloadimpedanceincreased, 5 Vpowersupply,withan8 load,themaximumambienttemperaturepossibl ewithoutviolatingthemaximumjunctiontempe ratureisapproximately96 functionofoutputpowerandthus,if typicaloperationisnotaroundthemaximumpow erdissipationpoint.

9 Propersupplybypassingis TypicalPerformanceCharacteristics, theeffectofa F anda F bypasscapacitorswhichaidinsupplystabilit y, ,especiallyCB, isthusdependantupondesiredlowfrequencyPS RR,clickandpopperformanceasexplainedin PROPERSELECTIONOFEXTERNALCOMPONENTS, systemcost, 1995 2013, NOVEMBER1995 REVISEDMAY2013 AUTOMATICSHUTDOWNCIRCUITA sshowninFigure3, theLM4880canbesetuptoautomaticallyshutdo wnwhena loadis basedupona (thevoltageonpin5 oftheLM4880) open,signifyingthatheadphonesareinserted , , ,RpandRoforma resistordividerwhichproducesa gatevoltageoflessthan5 A open,theoppositeconditionis clearlyvaluableinportableproductswhereba tterylifeis critical,butis alsobeneficialforpowerconsciousdesignssu chas GreenPC's.

10 AUTOMATICSWITCHINGCIRCUITA circuitcloselyrelatedtoAutomaticShutdown Circuitis AutomaticSwitchingCircuit. , , open,theLM4880is enabledandtheLM4861is disabledsincetheNMOS inverteris aheadphonejackis notpresent,it is shownin Figure4 tokeepthedrawingsimplebutthetypicalappli cationwoulda LM4880drivinga stereoexternalheadphonejackandtwoLM4861' required,a singleLM4861canbeusedasa summertomixtheleftandrightinputsintoa tolerantofexternalcomponentcombinations, unity-gainstablewhichgivesa +Nvalues, , largeextent,thebandwidthisdictatedbythec hoiceofexternalcomponentsshowninFigure2.