TPS54327 TI1 | Alldatasheet

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Vout (50 mV/div) Iout (2A/div) 100 s/div/c109 TPS54327 www.ti.com SLVSAG1 –NOVEMBER 2010 3-AOUTPUTSINGLESYNCHRONOUSSTEPDOWN SWITCHER WITHINTEGRATEDFET(SWIFTTM) Check forSamples: TPS54327 1FEATURES

DESCRIPTION

23• D-CAP2 ™ Mode Enables FastTransient Response The TPS54327 is an adaptiveon-timeD-CAP2 ™ mode synchronous buck converter.TheTPS54327• Low Output Rippleand Allows Ceramic Output enables system designersto complete the suiteofCapacitor variousend equipment’s power bus regulatorswitha• Wide VIN InputVoltageRange: 4.5V to18 V cost effective,low component count,low standby

  • Output VoltageRange: 0.76V to7.0V currentsolution.The main controlloop for the TPS54327 uses the D-CAP2 ™ mode controlwhich• HighlyEfficientIntegratedFET ’s Optimized providesa fasttransientresponse withno externalforLower Duty Cycle Applications compensationcomponents.The TPS54327 alsohas– 100 m Ω (HighSide)and 70 m Ω (Low Side) a proprietarycircuitthatenablesthedevicetoadopt• High Efficiency,lessthan 10 mA atshutdown tobothlow equivalentseriesresistance(ESR) output
  • High InitialBandgap ReferenceAccuracy capacitors,such as POSCAP or SP-CAP, and ultra-lowESR ceramic capacitors.The device• AdjustableSoftStart operatesfrom 4.5-Vto 18-V VIN input.The output• Pre-BiasedSoftStart voltagecan be programmed between 0.76V and 7 V.
  • 700-kHz SwitchingFrequency (fSW ) The devicealsofeaturesan adjustablesoftstarttime. The TPS54327 is availablein the 8-pin DDA• Cycle By Cycle Over CurrentLimit package, and designed to operatefrom –40°C to 85°C.APPLICATIONS
  • Wide Range ofApplicationsforLow Voltage System – DigitalTV Power Supply – High DefinitionBlu-rayDisc™ Players – Networking Home Terminal – DigitalSet Top Box (STB) Pleasebe aware thatan importantnoticeconcerningavailability,standardwarranty,and use incriticalapplicationsofTexas Instrumentssemiconductorproductsand disclaimerstheretoappearsattheend ofthisdatasheet. 2D-CAP2 isa trademarkofTexas Instruments. 3Blu-rayDiscisa trademarkofBlu-rayDiscAssociation. PRODUCTION DATA informationiscurrentas ofpublicationdate. Copyright© 2010,Texas InstrumentsIncorporatedProductsconform to specificationsper the terms of the Texas Instrumentsstandardwarranty.Productionprocessingdoes not necessarilyincludetestingofallparameters.

SLVSAG1 –NOVEMBER 2010 www.ti.com This integratedcircuitcan be damaged by ESD. Texas Instrumentsrecommends thatallintegratedcircuitsbe handled with appropriateprecautions.Failuretoobserveproperhandlingand installationprocedurescan cause damage. ESD damage can rangefromsubtleperformancedegradationtocompletedevicefailure.Precisionintegratedcircuitsmay be more susceptibletodamage because verysmallparametricchanges couldcause thedevicenottomeet itspublishedspecifications. ORDERING INFORMATION (1) TRANSPORTTA PACKAGE (2)(3) ORDERABLE PART NUMBER PIN MEDIA TPS54327DDA Tube –45°C to85°C DDA 8 TPS54327DDAR Tape and Reel (1) Forthemost currentpackage and orderinginformation,see thePackage OptionAddendum attheend ofthisdocument,orsee theTI web siteatwww.ti.com. (2) Package drawings,thermaldata,and symbolizationareavailableatwww.ti.com/packaging. (3) Allpackage optionshave Cu NIPDAU lead/ballfinish. ABSOLUTE MAXIMUM RATINGS overoperatingfree-airtemperaturerange(unlessotherwisenoted)(1) VALUE UNIT MIN MAX VIN,EN –0.3 20 V VBST –0.3 26 V VBST (10ns transient) –0.3 28 V Inputvoltagerange VBST (vsSW) –0.3 6.5 V VFB, SS –0.3 6.5 V SW –2 20 V SW (10ns transient) –3 22 V VREG5 –0.3 6.5 V Outputvoltagerange GND –0.3 0.3 V VoltagefromGND tothermalpad,Vdiff –0.2 0.2 V Human Body Model (HBM) 2 kV Electrostaticdischarge Charged DeviceModel (CDM) 500 V Operatingjunctiontemperature,TJ –40 150 °C Storagetemperature,Tstg –55 150 °C (1) Stressesbeyond thoselistedunderabsolutemaximum ratingsmay cause permanentdamage tothedevice.These arestressratings only,and functionaloperationofthedeviceattheseorany otherconditionsbeyond thoseindicatedunderrecommended operating conditionsisnotimplied.Exposuretoabsolute-maximum-ratedconditionsforextendedperiodsmay affectdevicereliability. THERMAL INFORMATION TPS54327 THERMAL METRIC (1) UNITS DDA (8PINS) qJA Junction-to-ambientthermalresistance 42.1 qJCtop Junction-to-case(top)thermalresistance 50.9 qJB Junction-to-boardthermalresistance 31.8 °C/W yJT Junction-to-topcharacterizationparameter 5 yJB Junction-to-boardcharacterizationparameter 13.5 qJCbot Junction-to-case(bottom)thermalresistance 7.1 (1) Formore informationabouttraditionaland new thermalmetrics,see theIC Package ThermalMetricsapplicationreport,SPRA953 .

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www.ti.com SLVSAG1 –NOVEMBER 2010 RECOMMENDED OPERATING CONDITIONS overoperatingfree-airtemperaturerange(unlessotherwisenoted) MIN MAX UNIT VIN Supplyinputvoltagerange 4.5 18 V VBST –0.1 24 VBST (10ns transient) -.0.1 27 VBST(vs SW) –0.1 5.7 SS –0.1 5.7 VI Inputvoltagerange EN –0.1 18 V VFB –0.1 5.5 SW –1.8 18 SW (10ns transient) –3 21 GND –0.1 0.1 VO Outputvoltagerange VREG5 –0.1 5.7 V IO OutputCurrentrange IVREG5 0 10 mA TA Operatingfree-airtemperature –40 85 °C TJ Operatingjunctiontemperature –40 150 °C

ELECTRICAL CHARACTERISTICS

overoperatingfree-airtemperaturerange(unlessotherwisenoted) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT SUPPLY CURRENT VIN current,TA = 25°C, EN = 5 V,IVIN Operating-non-switchingsupplycurrent 800 1200 mAVFB = 0.8V IVINSDN Shutdown supplycurrent VIN current,TA = 25°C, EN = 0 V 1.8 10 mA LOGIC THRESHOLD VENH EN high-levelinputvoltage EN 2 V VENL EN low-levelinputvoltage EN 0.45 V VFB VOLTAGE AND DISCHARGE RESISTANCE VFBTH VFB thresholdvoltage TA = 25°C, VO = 1.05V,continuousmode 749 765 781 mV IVFB VFB inputcurrent VFB = 0.8V,TA = 25°C 0 ±0.1 mA VREG5 OUTPUT TA = 25°C, 6.0V < VIN < 18 V,VVREG5 VREG5 outputvoltage 5.2 5.5 5.7 V0 < IVREG5 < 5 mA VLN5 Lineregulation 6 V < VIN < 18 V,IVREG5 = 5 mA 25 mV VLD5 Load regulation 0 mA < IVREG5 < 5 mA 100 mV IVREG5 Outputcurrent VIN = 6 V,VREG5 = 4.0V,TA = 25°C 60 mA MOSFET R DS(on)h Highsideswitchresistance 25°C, VBST -SW = 5.5V 100 m Ω R DS(on)l Low sideswitchresistance 25°C 70 m Ω CURRENT LIMIT Iocl Currentlimit L out= 1.5mH (1),TA = -20ºC to85ºC 3.5 4.2 5.7 A (1) Not productiontested. Copyright© 2010,Texas InstrumentsIncorporated 3 ProductFolderLink(s):TPS54327

SLVSAG1 –NOVEMBER 2010 www.ti.com ELECTRICAL CHARACTERISTICS (continued) overoperatingfree-airtemperaturerange(unlessotherwisenoted) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT THERMAL SHUTDOWN Shutdown temperature(2) 165 TSDN Thermalshutdownthreshold °C Hysteresis(2) 30 ON-TIME TIMER CONTROL tON On time VIN = 12 V,VO = 1.05V 150 ns tOFF(MIN) Minimum offtime TA = 25°C, VFB = 0.7V 260 310 ns SOFT START ISSC SS chargecurrent VSS = 0 V 1.4 2.0 2.6 mA ISSD SS dischargecurrent VSS = 0.5V 0.05 0.1 mA UVLO Wake up VREG5 voltage 3.45 3.75 4.05 UVLO UVLO threshold V HysteresisVREG5 voltage 0.19 0.32 0.45 (2) Not productiontested.

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(DDA) Exposed Thermal Pad TPS54327 www.ti.com SLVSAG1 –NOVEMBER 2010 DEVICE INFORMATION DDA PACKAGE (TOP VIEW) PIN FUNCTIONS PIN NAME NO. EN 1 Enableinputcontrol.Activehigh. VFB 2 Converterfeedbackinput.Connecttooutputvoltagewithfeedbackresistordivider. 5.5V power supplyoutput.A capacitor(typical1 µF)shouldbe connectedtoGND. VREG5 isnotactiveVREG5 3 when EN islow. SS 4 Soft-startcontrol.An externalcapacitorshouldbe connectedtoGND. Ground pin.Power groundreturnforswitchingcircuit.ConnectsensitiveSS and VFB returnstoGND atGND 5 a singlepoint. SW 6 Enablecontrolinput.EN isactivehighand must be pulledup toenablethedevice. Supplyinputforthehigh-sideFET gatedrivecircuit.Connect0.1µF capacitorbetween VBST and SWVBST 7 pins.An internaldiodeisconnectedbetween VREG5 and VBST. VIN 8 Inputvoltagesupplypin. Exposed Thermal Thermalpad ofthepackage.Must be solderedtoachieveappropriatedissipation.Must be connectedtoBack sidePad GND. Copyright© 2010,Texas InstrumentsIncorporated 5 ProductFolderLink(s):TPS54327

SLVSAG1 –NOVEMBER 2010 www.ti.com FUNCTIONAL BLOCK DIAGRAM

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C6(nF) x V C6(nF) x 0.765REFt (ms) = =SS I ( A ) 2SS /c109 TPS54327 www.ti.com SLVSAG1 –NOVEMBER 2010 OVERVIEW The TPS54327 isa 3-A synchronousstep-down(buck)converterwithtwo integratedN-channelMOSFETs. It operatesusingD-CAP2 ™ mode control.The fasttransientresponseof D-CAP2 ™ controlreducesthe output capacitancerequiredtomeet a specificlevelofperformance.Proprietaryinternalcircuitryallowstheuse oflow ESR outputcapacitorsincludingceramicand specialpolymertypes. DETAILED DESCRIPTION PWM Operation The main controlloopof the TPS54327 isan adaptiveon-timepulsewidthmodulation(PWM) controllerthat supportsa proprietaryD-CAP2 ™ mode control.D-CAP2 ™ mode controlcombines constanton-timecontrolwith an internalcompensationcircuitforpseudo-fixedfrequencyand low externalcomponent countconfigurationwith bothlowESR and ceramicoutputcapacitors.Itisstableeven withvirtuallyno rippleattheoutput. At thebeginningofeach cycle,thehigh-sideMOSFET isturnedon.ThisMOSFET isturnedoffafterinternalone shot timerexpires.This one shot isset by the converterinputvoltage,VIN, and the outputvoltage,VO, to maintaina pseudo-fixedfrequencyovertheinputvoltagerange,hence itiscalledadaptiveon-timecontrol.The one-shottimerisresetand thehigh-sideMOSFET isturnedon againwhen thefeedbackvoltagefallsbelow the referencevoltage.An internalramp isadded toreferencevoltagetosimulateoutputripple,eliminatingtheneed forESR inducedoutputripplefromD-CAP2 ™ mode control. PWM Frequency and AdaptiveOn-Time Control TPS54327 uses an adaptiveon-timecontrolscheme and does not have a dedicatedon board oscillator.The TPS54327 runswitha pseudo-constantfrequencyof700 kHz by usingtheinputvoltageand outputvoltageto settheon-timeone-shottimer.The on-timeisinverselyproportionaltotheinputvoltageand proportionaltothe outputvoltage,therefore,when thedutyratioisVOUT/VIN, thefrequencyisconstant. SoftStartand Pre-BiasedSoftStart The softstartfunctionisadjustable.When theEN pinbecomes high,2-mA currentbeginschargingthecapacitor whichisconnectedfromtheSS pintoGND. Smooth controloftheoutputvoltageismaintainedduringstartup. The equationfortheslowstarttimeisshown inEquation1.VFB voltageis0.765V and SS pinsourcecurrentis 2 mA. (1) The TPS54327 containsa uniquecircuittopreventcurrentfrombeingpulledfromtheoutputduringstartupifthe outputispre-biased.When thesoft-startcommands a voltagehigherthanthepre-biaslevel(internalsoftstart becomes greaterthanfeedbackvoltageVFB ),thecontrollerslowlyactivatessynchronousrectificationby starting the firstlow side FET gate driverpulses with a narrow on-time.Itthen incrementsthaton-timeon a cycle-by-cyclebasisuntilitcoincideswiththetimedictatedby (1-D),where D isthedutycycleoftheconverter. Thisscheme preventstheinitialsinkingofthepre-biasoutput,and ensurethattheoutvoltage(VO) startsand ramps up smoothlyintoregulationand the controlloopisgiventimeto transitionfrom pre-biasedstart-upto normalmode operation. CurrentProtection The outputovercurrentprotection(OCP) isimplementedusinga cycle-by-cyclevalleydetectcontrolcircuit.The switchcurrentismonitoredby measuringthelow-sideFET switchvoltagebetween theSW pinand GND. This voltageis proportionalto the switchcurrent.To improve accuracy,the voltagesensing is temperature compensated. Duringtheon timeofthehigh-sideFET switch,theswitchcurrentincreasesata linearratedeterminedby Vin, Vout,the on-timeand the outputinductorvalue.Duringthe on timeof the low-sideFET switch,thiscurrent decreaseslinearly.The averagevalueoftheswitchcurrentistheloadcurrentIOUT .The TPS54327 constantly monitorsthelow-sideFET switchvoltage,whichisproportionaltotheswitchcurrent,duringthelow-sideon-time. Ifthemeasured voltageisabove thevoltageproportionaltothecurrentlimit,an internalcounterisincremented per each SW cycleand theconvertermaintainsthelow-sideswitchon untilthemeasured voltageisbelow the voltagecorrespondingtothecurrentlimitatwhich timetheswitchingcycleisterminatedand a new switching Copyright© 2010,Texas InstrumentsIncorporated 7 ProductFolderLink(s):TPS54327

SLVSAG1 –NOVEMBER 2010 www.ti.com cyclebegins.Insubsequentswitchingcycles,theon-timeissettoa fixedvalueand thecurrentismonitoredin the same manner. Ifthe over currentconditionexistsfor7 consecutiveswitchingcycles,the internalOCL thresholdissettoa lowerlevel,reducingtheavailableoutputcurrent.When a switchingcycleoccurswhere the switchcurrentisnotabove thelowerOCL threshold,thecounterisresetand theOCL limitisreturnedtothe highervalue. There aresome importantconsiderationsforthistypeofover-currentprotection.The loadcurrentone halfofthe peak-to-peakinductorcurrenthigherthantheover-currentthreshold.Alsowhen thecurrentisbeinglimited,the outputvoltagetendsto fallas the demanded loadcurrentmay be higherthan the currentavailablefrom the converter.Thismay cause the outputvoltageto fall.When the over currentconditionisremoved, the output voltagewillreturntotheregulatedvalue.Thisprotectionisnon-latching. UVLO Protection Undervoltagelockoutprotection(UVLO) monitorsthevoltageoftheVREG5 pin.When theVREG5 voltageislower thanUVLO thresholdvoltage,theTPS54327 isshutoff.Thisisprotectionisnon-latching. Thermal Shutdown TPS54327 monitorsthetemperatureofitself.Ifthetemperatureexceeds thethresholdvalue(typically165°C), thedeviceisshutoff.Thisisnon-latchprotection.

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-50 0 50 100 150 T - Junction Temperature - °Cj I - Supply Current - µAVIN 2.0 4.0 6.0 8.0 10.0 -50 0 50 100 150 T - Junction Temperature - °Cj I - Supply Current - µAVINSDN 0 0.5 1 1.5 2 2.5 3 I -□Output□Current□- AO 1.04 1.05 1.06 1.07 1.08 V -□Output□Voltage□-□V O V =□12□VIN V =□18□VIN V =□5□VIN 100 0 2 4 6 8 10 12 14 16 18 20 V =□18□VIN EN□-□Input□Current□- A /c109 Vout□(50□mV/div) Iout□(2 A/div) 100 s/div/c109 0 5 10 15 20 V -□Input□Voltage□-□VI 1.04 1.05 1.06 1.07 1.08 V -□Output□Voltage□-□V O I =□1 AO I =□0 AO TPS54327 www.ti.com SLVSAG1 –NOVEMBER 2010 TYPICAL CHARACTERISTICS Figure1.VIN CURRENT vs JUNCTION TEMPERATURE Figure2.VIN SHUTDOWN CURRENT vs JUNCTION TEMPERATURE Figure3.EN CURRENT vs EN VOLTAGE Figure4.1.05-VOUTPUT VOLTAGE vs OUTPUT CURRENT Figure5.1.05-VOUTPUT VOLTAGE vs INPUT VOLTAGE Figure6.1.05-V,50-mA to2-A LOAD TRANSIENT RESPONSE Copyright© 2010,Texas InstrumentsIncorporated 9 ProductFolderLink(s):TPS54327

EN□(10□V/div) VREG5□(5□V/div) 1□ms/div) Vout□(0.5□V/div) 0 1 2 3 4 I - Output Current - AO 100 Efficiency - % V = 1.8 VO V = 2.5 VO V = 3.3 VO 400 450 500 550 600 650 700 750 800 850 900 0 0.5 1 1.5 2 2.5 3 I -□Output□Current□- AO f -□Switching□Frequency□-□kHzs V =□3.3□VO V =□1.8□VO V =□1.05□VO 400 450 500 550 600 650 700 750 800 850 900 0 5 10 15 20 V -□Input□Voltage□-□VIN f -□Switching□Frequency□-□kHzs V =□1.8□VO V =□1.05□VO I =□1 AO V =□3.3□VO V (10□mV/div)OV =□1.05□VO SW□(5□V/div) V =□1.05□VO V (50□mV/div)IN SW□(5□V/div) TPS54327 SLVSAG1 –NOVEMBER 2010 www.ti.com TYPICAL CHARACTERISTICS (continued) Figure7.START-UP WAVE FORM Figure8.EFFICIENCY vs OUTPUT CURRENT Figure9.SWITCHING FREQUENCY vs INPUT VOLTAGE Figure10.SWITCHING FREQUENCY vs OUTPUT CURRENT Figure11.VOLTAGE RIPPLE AT OUTPUT (IO = 2 A) Figure12.VOLTAGE RIPPLE AT INPUT (IO = 2 A)

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V = 0.765 xOUT R11 + R2 /c230 /c246 /c247/c231 /c247/c231 /c247 /c247/c231 /c232 /c248 F =P OUT OUT

2 L x C/c112

www.ti.com SLVSAG1 –NOVEMBER 2010 DESIGN GUIDE Step By Step Design Procedure To beginthedesignprocess,you must know a few applicationparameters:

  • Inputvoltagerange
  • Outputvoltage
  • Outputcurrent
  • Outputvoltageripple
  • Inputvoltageripple Figure13. Shows theschematic diagram forthisdesign example. Output VoltageResistorsSelection The outputvoltageissetwitha resistordividerfrom theoutputnode totheVFB pin.Itisrecommended touse 1% toleranceorbetterdividerresistors.Startby usingEquation2 tocalculateVOUT . To improveefficiencyatverylightloadsconsiderusinglargervalueresistors,toohighofresistancewillbe more susceptibletonoiseand voltageerrorsfromtheVFB inputcurrentwillbe more noticeable. (2) Output FilterSelection The outputfilterused withtheTPS54327 isan LC circuit.ThisLC filterhas doublepoleat: (3) At low frequencies,theoverallloopgainissetby theoutputset-pointresistordividernetworkand theinternal gainoftheTPS54327. The low frequencyphase is180 degrees.At theoutputfilterpolefrequency,thegainrolls offata -40 dB per decade rateand thephase dropsrapidly.D-CAP2 ™ introducesa highfrequencyzerothat reducesthegainrolloffto-20 dB per decade and increasesthephase to90 degreesone decade above the zerofrequency.The inductorand capacitorselectedfortheoutputfiltermust be selectedso thatthedoublepole ofEquation3 islocatedbelow thehighfrequencyzerobutcloseenough thatthephase boostprovidedbe the high frequencyzero providesadequate phase margin fora stablecircuit.To meet thisrequirementuse the valuesrecommended inTable1 Copyright© 2010,Texas InstrumentsIncorporated 11 ProductFolderLink(s):TPS54327

V VV IN(max) OUTOUT= xIPP V L xIN(max) O SW /c73 f lpp= +Ipeak O 2 /c73 /c73 /c73 2 2= IPPLo(RMS) O 1+ 12 /c73 /c73 /c73 INOUT OUT=Co(RMS) IN O SW V x (V - V ) 12 x V x L x /c73 f TPS54327 SLVSAG1 –NOVEMBER 2010 www.ti.com Table1.Recommended Component Values Output Voltage(V) R1 (kΩ) R2 (kΩ) C4 (pF) L1 (µH) C8 + C9 (µF) 1 6.81 22.1 1.5 22 -68 1.05 8.25 22.1 1.5 22 -68 1.2 12.7 22.1 1.5 22 -68 1.8 30.1 22.1 5 -22 2.2 22 -68 2.5 49.9 22.1 5 -22 2.2 22 -68 3.3 73.2 22.1 5 -22 2.2 22 -68 5 124 22.1 5 -22 3.3 22 -68 6.5 165 22.1 5 -22 3.3 22 -68 SincetheDC gainisdependenton theoutputvoltage,therequiredinductorvaluewillincreaseas theoutput voltageincreases.For higheroutputvoltagesabove 1.8V, additionalphase boostcan be achievedby addinga feedforwardcapacitor(C4)inparallelwithR1 The inductorpeak-to-peakripplecurrent,peak currentand RMS currentare calculatedusing Equation4, Equation5 and Equation6. The inductorsaturationcurrentratingmust be greaterthan the calculatedpeak currentand theRMS orheatingcurrentratingmust be greaterthanthecalculatedRMS current.Use 700 kHz for fSW . Use 700 kHz forfSW .Make surethechosen inductorisratedforthepeak currentofEquation5 and theRMS currentofEquation6. (4) (5) (6) For thisdesignexample,thecalculatedpeak currentis3.47A and thecalculatedRMS currentis3.01A. The inductorused isa TDK SPM6530-1R5M100 witha peak currentratingof11.5A and an RMS currentratingof11 The capacitorvalueand ESR determinestheamount ofoutputvoltageripple.The TPS54327 isintendedforuse withceramicor otherlow ESR capacitors.Recommended valuesrange from 22uF to68uF. Use Equation7 to determinetherequiredRMS currentratingfortheoutputcapacitor. (7) For thisdesigntwo TDK C3216X5R0J226M 22uF outputcapacitorsare used.The typicalESR is2 m Ω each. The calculatedRMS currentis.271Aand each outputcapacitorisratedfor4A. InputCapacitorSelection The TPS54327 requiresan inputdecouplingcapacitorand a bulk capacitoris needed depending on the application.A ceramiccapacitorover10 mF isrecommended forthedecouplingcapacitor.An additional0.1µF capacitorfrom pin14 toground isrecommended toimprovethestabilityoftheover-currentlimitfunction.The capacitorvoltageratingneeds tobe greaterthanthemaximum inputvoltage. BootstrapCapacitorSelection A 0.1 µF. ceramic capacitormust be connected between the VBST to SW pin forproperoperation.Itis recommended touse a ceramiccapacitor. VREG5 CapacitorSelection A 1-µF. ceramic capacitormust be connected between the VREG5 to GND pin forproperoperation.Itis recommended touse a ceramiccapacitor.

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www.ti.com SLVSAG1 –NOVEMBER 2010 THERMAL INFORMATION This8-pinDDA package incorporatesan exposed thermalpad thatisdesignedto be directlyto an external heartsick.The thermalpad must be soldereddirectlytotheprintedboard(PCB).Aftersoldering,thePCB can be used as a heartsick.Inaddition,throughtheuse ofthermalvias,thethermalpad can be attacheddirectlytothe appropriatecopperplaneshown intheelectricalschematicforthedevice,oralternatively,can be attachedtoa specialheartsickstructuredesignedintothe PCB. Thisdesignoptimizesthe heat transferfrom the integrated circuit(IC). For additionalinformationon the exposed thermalpad and how to use the advantageof itsheat dissipating abilities,refertoTechnicalBrief,PowerPAD ™ ThermallyEnhanced Package,Texas InstrumentsLiteratureNo. SLMA002 and ApplicationBrief,PowerPAD ™ Made Easy,Texas InstrumentsLiteratureNo. SLMA004 . The exposed thermalpad dimensionsforthispackage areshown inthefollowingillustration. Figure14. Thermal Pad Dimensions (Top View) Copyright© 2010,Texas InstrumentsIncorporated 13 ProductFolderLink(s):TPS54327

SLVSAG1 –NOVEMBER 2010 www.ti.com LAYOUT CONSIDERATIONS 1. Keep theinputswitchingcurrentloopas smallas possible. 2. Keep the SW node as physicallysmall and shortas possibleto minimizeparasiticcapacitanceand inductanceand tominimizeradiatedemissions.Kelvinconnectionsshouldbe broughtfromtheoutputtothe feedbackpinofthedevice. 3. Keep analogand non-switchingcomponents away fromswitchingcomponents. 4. Make a singlepointconnectionfromthesignalgroundtopower ground. 5. Do notallowswitchingcurrenttoflowunderthedevice. 6. Keep thepatternlinesforVIN and PGND broad. 7. Exposed pad ofdevicemust be connectedtoPGND withsolder. 8. VREG5 capacitorshouldbe placednearthedevice,and connectedPGND. 9. Outputcapacitorshouldbe connectedtoa broadpatternofthePGND. 10. Voltagefeedbackloopshouldbe as shortas possible,and preferablywithgroundshield. 11. Lower resistorofthevoltagedividerwhichisconnectedtotheVFB pinshouldbe tiedtoSGND. 12. ProvidingsufficientviaispreferableforVIN,SW and PGND connection. 13. PCB patternforVIN,SW, and PGND shouldbe as broadas possible. 14. VIN Capacitorshouldbe placedas nearas possibletothedevice. Figure15. PCB Layout

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www.ti.com 4-Dec-2010 Addendum-Page 1 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Drawing Pins Package Qty Eco Plan (2) Lead/ Ball Finish MSL Peak Temp (3) Samples (Requires Login) TPS54327DDA ACTIVE SO PowerPAD DDA 8 75 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR Purchase Samples TPS54327DDAR ACTIVE SO PowerPAD DDA 8 2500 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR Purchase Samples (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material) (3) MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release. In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.

*All dimensions are nominal Device Package Type Package Drawing Pins SPQ Reel Diameter (mm) Reel Width W1 (mm) (mm) (mm) (mm) (mm) W (mm) Pin1 Quadrant TPS54327DDAR SO Power PAD PACKAGE MATERIALS INFORMATION www.ti.com 2-Dec-2010 Pack Materials-Page 1

*All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) TPS54327DDAR SO PowerPAD DDA 8 2500 346.0 346.0 29.0 PACKAGE MATERIALS INFORMATION www.ti.com 2-Dec-2010 Pack Materials-Page 2

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