LM20123 www.ti.com SNVS524E–OCTOBER2007–REVISEDMARCH2013 ® LM20123/LM20123Q 3A, 1.5MHz PowerWise Synchronous Buck Regulator CheckforSamples:LM20123 FEATURES DESCRIPTION 1 • LM20123QisAEC-Q100Qualifiedand The LM20123 is a full featured 1.5 MHz synchronous 2 buck regulator capable of delivering up to 3A of ManufacturedonanAutomotiveGradeFlow continuous output current. The current mode control • InputVoltageRange2.95Vto5.5V loop can be compensated to be stable with virtually • AccurateCurrentLimitMinimizesInductor any type of output capacitor. For most cases, Size compensating the device only requires two external components, providing maximum flexibility and ease • 96%Efficiencywith1.5MHzSwitching of use. The device is optimized to work over the input Frequency voltage range of 2.95V to 5.5V making it suited for a • 32mΩIntegratedFETSwitches widevarietyoflowvoltagesystems. • StartsupintoPre-BiasedLoads The device features internal over voltage protection • OutputVoltageTracking (OVP) and over current protection (OCP) circuits for • PeakCurrentModeControl increased system reliability. A precision enable pin and integrated UVLO allows the turn on of the device • AdjustableOutputVoltageDownto0.8V to be tightly controlled and sequenced. Start-up • AdjustableSoft-StartwithExternalCapacitor inrush currents are limited by both an internally fixed • PrecisionEnablePinwithHysteresis and externally adjustable Soft-Start circuit. Fault detection and supply sequencing is possible with the • IntegratedOVP,UVLO,PowerGoodand integratedpowergoodcircuit. ThermalShutdown • HTSSOP(16-Pins)ExposedPadPackage The LM20123 is designed to work well in multi-rail power supply architectures. The output voltage of the device can be configured to track a higher voltage rail APPLICATIONS using the SS/TRK pin. If the output of the LM20123 is • SimpletoDesign,HighEfficiencyPointof pre-biased at startup it will not sink current to pull the LoadRegulationfroma5Vor3.3VBus output low until the internal soft-start ramp exceeds thevoltageatthefeedbackpin. • HighPerformanceDSPs,FPGAs,ASICsand Microprocessors The LM20123 is offered in a 16-pin HTSSOP • Broadband,NetworkingandOptical package with an exposed pad that can be soldered to CommunicationsInfrastructure thePCB,eliminatingtheneedforbulkyheatsinks. Typical Application Circuit LM20123 L VIN PVIN SW VOUT RFB1 CIN RF EN FB COUT AVIN RFB2 PGOOD CF COMP VCC RC1 SS/TRK CVCC PGND AGND CC1 CSS (optional) 1 Pleasebeawarethatanimportantnoticeconcerningavailability,standardwarranty,anduseincriticalapplicationsof TexasInstrumentssemiconductorproductsanddisclaimerstheretoappearsattheendofthisdatasheet. Alltrademarksarethepropertyoftheirrespectiveowners. 2 PRODUCTIONDATAinformationiscurrentasofpublicationdate. Copyright©2007–2013,TexasInstrumentsIncorporated Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarilyincludetestingofallparameters.

LM20123 SNVS524E–OCTOBER2007–REVISEDMARCH2013 www.ti.com This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with appropriateprecautions.Failuretoobserveproperhandlingandinstallationprocedurescancausedamage. ESDdamagecanrangefromsubtleperformancedegradationtocompletedevicefailure.Precisionintegratedcircuitsmaybemore susceptibletodamagebecauseverysmallparametricchangescouldcausethedevicenottomeetitspublishedspecifications. ConnectionDiagram TopView SS/TRK 1 16 NC FB 2 15 AGND PGOOD 3 14 AVIN COMP 4 13 VCC EP NC 5 12 EN PVIN 6 11 PGND PVIN 7 10 PGND SW 8 9 SW SeePackageNumberPWP0016A PINDESCRIPTIONS Pin# Name Description 1 SS/TRK Soft-StartorTrackingcontrolinput.Aninternal5µAcurrentsourcechargesanexternalcapacitortosetthe Soft-Startramprate.Ifdrivenbyaexternalsourcelessthan800mV,thispinoverridestheinternalreference thatsetstheoutputvoltage.Ifleftopen,aninternal1msSoft-Startrampisactivated. 2 FB Feedbackinputtotheerroramplifierfromtheregulatedoutput.Thispinisconnectedtotheinvertinginputof theinternaltransconductanceerroramplifier.An800mVreferenceconnectedtothenon-invertinginputofthe erroramplifiersetstheclosedloopregulationvoltageattheFBpin. 3 PGOOD Powergoodoutputsignal.Opendrainoutputindicatingtheoutputvoltageisregulatingwithintolerance.Apull- upresistorof10kΩto100kΩisrecommendformostapplications. 4 COMP Externalcompensationpin.Connectaresistorandcapacitortothispintocompensatethedevice. 5,16 NC ThesepinsmustbeconnectedtoGNDtoensureproperoperation. 6,7 PVIN Inputvoltagetothepowerswitchesinsidethedevice.Thesepinsshouldbeconnectedtogetheratthedevice. AlowESRcapacitorshouldbeplacednearthesepinstostabilizetheinputvoltage. 8,9 SW Switchpin.ThePWMoutputoftheinternalpowerswitches. 10,11 PGND Powergroundpinfortheinternalpowerswitches. 12 EN Precisionenableinputforthedevice.Anexternalvoltagedividercanbeusedtosetthedeviceturn-on threshold.IfnotusedtheENpinshouldbeconnectedtoPVIN. 13 VCC Internal2.7Vsub-regulator.Thispinshouldbebypassedwitha1µFceramiccapacitor. 14 AVIN Analoginputsupplythatgeneratestheinternalbias.MustbeconnectedtoVINthroughalowpassRCfilter. 15 AGND Quietanaloggroundfortheinternalbiascircuitry. EP ExposedPad Exposedmetalpadontheundersideofthepackagewithaweakelectricalconnectiontoground.Itis recommendedtoconnectthispadtothePCboardgroundplaneinordertoimproveheatdissipation. 2 SubmitDocumentationFeedback Copyright©2007–2013,TexasInstrumentsIncorporated ProductFolderLinks:LM20123

LM20123 www.ti.com SNVS524E–OCTOBER2007–REVISEDMARCH2013 ABSOLUTE MAXIMUM RATINGS(1) VoltagesfromtheindicatedpinstoGND AVIN,PVIN,EN,PGOOD,SS/TRK,COMP,FB,SW -0.3Vto+6V StorageTemperature -65°Cto150°C JunctionTemperature 150°C PowerDissipation(2) 2.6W LeadTemperature(Soldering,10sec) 260°C MinimumESDRating(3) ±2kV (1) AbsoluteMaximumRatingsindicatelimitsbeyondwhichdamagetothedevicemayoccur.OperatingRatingsindicateconditionsfor whichthedeviceisintendedtobefunctional,butdonotspecificperformancelimits.Forspecificationsandtestconditions,seethe ElectricalCharacteristics. (2) Themaximumallowablepowerdissipationisafunctionofthemaximumjunctiontemperature,T ,thejunctions-to-ambientthermal J_MAX resistance,θ ,andtheambienttemperature,T .Themaximumallowablepowerdissipationatanyambienttemperatureiscalculated JA A using:P =(T –T )/θ .Themaximumpowerdissipationsof2.6WisdeterminedusingT =25°C,θ =38°C/W,andT D_MAX J_MAX A JA A JA J_MAX =125°C. (3) Thehumanbodymodelisa100pFcapacitordischargedthrougha1.5kΩresistortoeachpin. OPERATING RATINGS PVIN,AVINtoGND 2.95Vto5.5V JunctionTemperature −40°Cto+125°C Copyright©2007–2013,TexasInstrumentsIncorporated SubmitDocumentationFeedback 3 ProductFolderLinks:LM20123

LM20123 SNVS524E–OCTOBER2007–REVISEDMARCH2013 www.ti.com ELECTRICAL CHARACTERISTICS Unlessotherwisestated,thefollowingconditionsapply:AVIN=PVIN=VIN=5V.LimitsinstandardtypeareforT =25°C J only,limitsinboldfacetypeapplyoverthejunctiontemperature(T)rangeof-40°Cto+125°C.MinimumandMaximumlimits J arespecifedbytest,design,orstatisticalcorrelation.TypicalvaluesrepresentthemostlikelyparametricnormatT =25°C, J andareprovidedforreferencepurposesonly. Symbol Parameter Conditions Min Typ Max Unit V Feedbackpinvoltage V =2.95Vto5.5V 0.788 0.8 0.81 V FB IN 2 ΔV /ΔI LoadRegulation I =100mAto3A 0.08 %/A OUT OUT OUT I SwitchCurrentLimitThreshold V =3.3V 4.3 4.8 5.3 A CL IN R High-SideSwitchOnResistance I =3.5A 36 55 mΩ DS_ON SW R Low-SideSwitchOnResistance I =3.5A 32 52 mΩ DS_ON SW I OperatingQuiescentCurrent Non-switching,V =V 3.5 6 mA Q FB COMP I ShutdownQuiescentcurrent V =0V 90 180 µA SD EN V VINUnderVoltageLockout RisingV 2.45 2.7 2.95 V UVLO IN V VINUnderVoltageLockoutHysteresis FallingV 45 100 mV UVLO_HYS IN V VCCVoltage I =0µA 2.45 2.7 2.95 V VCC VCC I Soft-StartPinSourceCurrent V =0V 2 4.5 7 µA SS SS/TRK V SS/TRKAccuracy,V -V V =0.4V -10 3 15 mV TRACK SS FB SS/TRK Oscillator F OscillatorFrequency 1350 1500 1650 kHz OSC DC MaximumDutyCycle I =0A 85 % MAX LOAD T MinimumOnTime 100 ns ON_TIME T CurrentSenseBlankingTime AfterRisingV 80 ns CL_BLANK SW ErrorAmplifierandModulator I Feedbackpinbiascurrent V =0.8V 1 100 nA FB FB I COMPOutputSourceCurrent V =V =0.6V 80 100 µA COMP_SRC FB COMP I COMPOutputSinkCurrent V =1.0V,V =0.6V 80 100 µA COMP_SNK FB COMP g ErrorAmplifierTransconductance I =±50µA 450 510 600 µmho m COMP A ErrorAmplifierVoltageGain 2000 V/V VOL PowerGood V OverVoltageProtectionRisingThreshold WithrespecttoV 105 108 111 % OVP FB V OverVoltageProtectionHysteresis 2 3 % OVP_HYS V PGOODRisingThreshold WithrespecttoV 92 94 96 % PGTH FB V PGOODFallingHysteresis 2 3 % PGHYS T PGOODdeglitchtime 16 µs PGOOD I PGOODLowSinkCurrent V =0.4V 0.6 1 mA OL PGOOD I PGOODHighLeakageCurrent V =5V 5 100 nA OH PGOOD Logic V ENPinTurnonThreshold V Rising 1.08 1.18 1.28 V IH_EN EN V ENPinHysteresis 66 mV EN_HYS ThermalShutdown T ThermalShutdown 160 °C SD T ThermalShutdownHysteresis 10 °C SD_HYS ThermalResistance θ JunctiontoAmbient 38 °C/W JA 4 SubmitDocumentationFeedback Copyright©2007–2013,TexasInstrumentsIncorporated ProductFolderLinks:LM20123

LM20123 www.ti.com SNVS524E–OCTOBER2007–REVISEDMARCH2013 TYPICAL PERFORMANCE CHARACTERISTICS Unlessotherwisespecified:C =C =100µF,L=1.0µH(CoilcraftMSS1038),V =5V,V =1.2V,R =1.2Ω,T = IN OUT IN OUT LOAD A 25°Cforefficiencycurves,loopgainplotsandwaveforms,andT =25°Cforallothers. J Efficiencyvs. Efficiencyvs. LoadCurrent(V =5V) LoadCurrent(V =3.3V) IN IN Figure1. Figure2. High-SideFETresistance Low-SideFETresistance vs.Temperature vs.Temperature Figure3. Figure4. ErrorAmplifierGain vs.Frequency LineRegulation Figure5. Figure6. Copyright©2007–2013,TexasInstrumentsIncorporated SubmitDocumentationFeedback 5 ProductFolderLinks:LM20123

LM20123 SNVS524E–OCTOBER2007–REVISEDMARCH2013 www.ti.com TYPICAL PERFORMANCE CHARACTERISTICS (continued) Unlessotherwisespecified:C =C =100µF,L=1.0µH(CoilcraftMSS1038),V =5V,V =1.2V,R =1.2Ω,T = IN OUT IN OUT LOAD A 25°Cforefficiencycurves,loopgainplotsandwaveforms,andT =25°Cforallothers. J FeedbackPinVoltage LoadRegulation vs.Temperature Figure7. Figure8. SwitchingFrequency QuiescentCurrentvs. vs.Temperature V (NotSwitching) IN Figure9. Figure10. ShutdownCurrent EnableThreshold vs.Temperature vs.Temperature Figure11. Figure12. 6 SubmitDocumentationFeedback Copyright©2007–2013,TexasInstrumentsIncorporated ProductFolderLinks:LM20123

LM20123 www.ti.com SNVS524E–OCTOBER2007–REVISEDMARCH2013 TYPICAL PERFORMANCE CHARACTERISTICS (continued) Unlessotherwisespecified:C =C =100µF,L=1.0µH(CoilcraftMSS1038),V =5V,V =1.2V,R =1.2Ω,T = IN OUT IN OUT LOAD A 25°Cforefficiencycurves,loopgainplotsandwaveforms,andT =25°Cforallothers. J UVLOThreshold PeakCurrentLimit vs.Temperature vs.Temperature Figure13. Figure14. PeakCurrentLimitvs.V PeakCurrentLimitvs.V OUT IN Figure15. Figure16. LoadTransientResponse LineTransientResponse Figure17. Figure18. Copyright©2007–2013,TexasInstrumentsIncorporated SubmitDocumentationFeedback 7 ProductFolderLinks:LM20123

LM20123 SNVS524E–OCTOBER2007–REVISEDMARCH2013 www.ti.com TYPICAL PERFORMANCE CHARACTERISTICS (continued) Unlessotherwisespecified:C =C =100µF,L=1.0µH(CoilcraftMSS1038),V =5V,V =1.2V,R =1.2Ω,T = IN OUT IN OUT LOAD A 25°Cforefficiencycurves,loopgainplotsandwaveforms,andT =25°Cforallothers. J Start-Up(Soft-Start) Start-Up(Tracking) Figure19. Figure20. PowerDown ShortCircuitInputCurrentvsV IN Figure21. Figure22. V vs.I PGOOD PGOOD Figure23. 8 SubmitDocumentationFeedback Copyright©2007–2013,TexasInstrumentsIncorporated ProductFolderLinks:LM20123

LM20123 www.ti.com SNVS524E–OCTOBER2007–REVISEDMARCH2013 BLOCK DIAGRAM +2.7V REGULATOR AVIN VCC + UVLO 2.7V - SLOPE COMP PVIN COMP 2.7V + CURRENT SENSE 5 PA DISCHARGE(50 Ps) SS/TRK ERROR AMP gm = 510 Pmho + CURRENT DISCHARGE - LIMIT FB + + VREF 4.8A - PVIN + - 800 mV + - PWM COMPARATOR DIODE + OVERVOLTAGE EMULATION 864 mV - PG-L CONTROL +- SW 752 mV + UNDERVOLTAGE LOGIC - PVIN THERMAL PROTECTION + EN 1.18V - PGND PG-L OSCILLATOR PGOOD AGND Copyright©2007–2013,TexasInstrumentsIncorporated SubmitDocumentationFeedback 9 ProductFolderLinks:LM20123

LM20123 SNVS524E–OCTOBER2007–REVISEDMARCH2013 www.ti.com OPERATION DESCRIPTION GENERAL The LM20123 switching regulator features all of the functions necessary to implement an efficient low voltage buck regulator using a minimum number of external components. This easy to use regulator features two integratedswitchesandiscapableofsupplyingupto3Aofcontinuousoutputcurrent.Theregulatorutilizespeak current mode control with nonlinear slope compensation to optimize stability and transient response over the entire output voltage range. Peak current mode control also provides inherent line feed-forward, cycle-by-cycle current limiting and easy loop compensation. The fixed 1.5 MHz operating frequency minimizes the inductor size whilestillachievingefficienciesupto96%.Theprecisioninternalvoltagereferenceallowstheoutputtobesetas low as 0.8V. Fault protection features include: current limiting, thermal shutdown, over voltage protection, and shutdown capability. The device is available in the HTSSOP 16-Pin package featuring an exposed pad to aid thermal dissipation. The LM20123 can be used in numerous applications to efficiently step-down from a 5V or 3.3Vbus.ThetypicalapplicationcircuitfortheLM20123isshowninFigure25inthedesignguide. PRECISION ENABLE The enable (EN) pin allows the output of the device to be enabled or disabled with an external control signal. Thispinisaprecisionanaloginputthatenablesthedevicewhenthevoltageexceeds1.18V(typical).TheENpin has 66 mV of hysteresis and will disable the output when the enable voltage falls below 1.11V (typical). If the EN pin is not used, it should be connected to VIN. Since the enable pin has a precise turn on threshold it can be used along with an external resistor divider network from V to configure the device to turn on at a precise input IN voltage.Theprecisionenablecircuitrywillremainactiveevenwhenthedeviceisdisabled. PEAK CURRENT MODE CONTROL In most cases, the peak current mode control architecture used in the LM20123 only requires two external components to achieve a stable design. The compensation can be selected to accommodate any capacitor type or value. The external compensation also allows the user to set the crossover frequency and optimize the transientperformanceofthedevice. For duty cycles above 50% all current mode control buck converters require the addition of an artificial ramp to avoid sub-harmonic oscillation. This artificial linear ramp is commonly referred to as slope compensation. What makes the LM20123 unique is the amount of slope compensation will change depending on the output voltage. When operating at high output voltages the device will have more slope compensation than when operating at lower output voltages. This is accomplished in the LM20123 by using a non-linear parabolic ramp for the slope compensation. The parabolic slope compensation of the LM20123 is much better than the traditional linear slope compensationbecauseitoptimizesthestabilityofthedeviceovertheentireoutputvoltagerange. CURRENT LIMIT The precise current limit of the LM20123 is set at the factory to be within 10% over the entire operating temperature range. This enables the device to operate with smaller inductors that have lower saturation currents. When the peak inductor current reaches the current limit threshold, an over current event is triggered and the internal high-side FET turns off and the low-side FET turns on allowing inductor current to ramp down until the next switching cycle. For each sequential over-current event, the reference voltage is decremented and PWM pulses are skipped resulting in a current limit that does not aggressively fold back for brief over-current events, whileatthesametimeprovidingfrequencyandvoltagefoldbackprotectionduringhardshortcircuitconditions. SOFT-START AND VOLTAGE TRACKING The SS/TRK pin is a dual function pin that can be used to set the start up time or track an external voltage source.ThestartuporSoft-StarttimecanbeadjustedbyconnectingacapacitorfromtheSS/TRKpintoground. The Soft-Start feature allows the regulator output to gradually reach the steady state operating point, thus reducingstressesontheinputsupplyandcontrollingstartupcurrent.IfnoSoft-Startcapacitorisusedthedevice defaults to the internal Soft-Start circuitry resulting in a start up time of approximately 1 ms. For applications that require a monotonic start up or utilize the PGOOD pin, an external Soft-Start capacitor is recommended. The SS/TRK pin can also be set to track an external voltage source. The tracking behavior can be adjusted by two externalresistorsconnectedtotheSS/TRKpinasshowninFigure30inthedesignguide. 10 SubmitDocumentationFeedback Copyright©2007–2013,TexasInstrumentsIncorporated ProductFolderLinks:LM20123

LM20123 www.ti.com SNVS524E–OCTOBER2007–REVISEDMARCH2013 PRE-BIAS START UP CAPABILITY The LM20123 is in a pre-biased state when the device starts up with an output voltage greater than zero. This often occurs in many multi-rail applications such as when powering an FPGA, ASIC, or DSP. In these applications the output can be pre-biased through parasitic conduction paths from one supply rail to another. Even though the LM20123 is a synchronous converter it will not pull the output low when a prebias condition exists.DuringstartuptheLM20123willnotsinkcurrentuntiltheSoft-StartvoltageexceedsthevoltageontheFB pin. Since the device can not sink current it protects the load from damage that might otherwise occur if current isconductedthroughtheparasiticpathsoftheload. POWER GOOD AND OVER VOLTAGE FAULT HANDLING The LM20123 has built in under and over voltage comparators that control the power switches. Whenever there is an excursion in output voltage above the set OVP threshold, the part will terminate the present on-pulse, turn on the low side FET, and pull the PGOOD pin low. The low side FET will remain on until either the FB voltage falls back into regulation or the zero cross detection is triggered which in turn tri-states the FETs. If the output reaches the UVP threshold the part will continue switching and the PGOOD pin will be asserted and go low. Typical values for the PGOOD resistor are on the order of 100 kΩ or less. To avoid false tripping during transient glitchesthePGOODpinhas16µsofbuiltindeglitchtimetobothrisingandfallingedges. UVLO The LM20123 has a built-in under-voltage lockout protection circuit that keeps the device from switching until the input voltage reaches 2.7V (typical). The UVLO threshold has 45 mV of hysteresis that keeps the device from responding to power-on glitches during start up. If desired, the turn-on point of the supply can be changed by using the precision enable pin and a resistor divider network connected to V as shown in Figure 29 in the IN designguide. THERMAL PROTECTION Internal thermal shutdown circuitry is provided to protect the integrated circuit in the event that the maximum junction temperature is exceeded. When activated, typically at 160°C, the LM20123 tri-states the power FETs and resets soft start. After the junction cools to approximately 150°C, the part starts up using the normal start up routine.Thisfeatureisprovidedtopreventcatastrophicfailuresfromaccidentaldeviceoverheating. LIGHT LOAD OPERATION The LM20123 offers increased efficiency when operating at light loads. Whenever the load current is reduced to a point where the peak to peak inductor ripple current is greater than two times the load current, the part will enter the diode emulation mode preventing significant negative inductor current. The point at which this occurs is thecriticalconductionboundaryandcanbecalculatedbythefollowingequation: (VIN – VOUT) x D IBOUNDARY = 2 x L x fSW (1) Several diagrams are shown in Figure 24 illustrating continuous conduction mode (CCM), discontinuous conductionmode,andtheboundarycondition. It can be seen that in diode emulation mode, whenever the inductor current reaches zero the SW node will become high impedance. Ringing will occur on this pin as a result of the LC tank circuit formed by the inductor and the parasitic capacitance at the node. If this ringing is of concern an additional RC snubber circuit can be addedfromtheswitchnodetoground. Atverylightloads,usuallybelow100mA,severalpulsesmaybeskippedinbetweenswitchingcycles,effectively reducingtheswitchingfrequencyandfurtherimprovinglight-loadefficiency. Copyright©2007–2013,TexasInstrumentsIncorporated SubmitDocumentationFeedback 11 ProductFolderLinks:LM20123

LM20123 SNVS524E–OCTOBER2007–REVISEDMARCH2013 www.ti.com e g Continuous Conduction Mode (CCM) a Volt VIN e d o n h c wit S Time (s) nt Continuous Conduction Mode (CCM) e urr C ctor IAVERAGE u d n I Time (s) nt e urr DCM - CCM Boundary C or ct u nd IAVERAGE I Time (s) e g Discontinuous Conduction Mode (DCM) a olt VIN V e d o n h c wit S Time (s) nt e urr Discontinuous Conduction Mode (DCM) C or ct du IPeak n I Time (s) Figure24. ModesofOperationforLM20123 Design Guide This section walks the designer through the steps necessary to select the external components to build a fully functional power supply. As with any DC-DC converter numerous trade-offs are possible to optimize the design for efficiency, size, or performance. These will be taken into account and highlighted throughout this discussion. To facilitate component selection discussions the circuit shown in Figure 25 below may be used as a reference. Unless otherwise indicated all formulas assume units of amps (A) for current, farads (F) for capacitance, henries (H)forinductanceandvolts(V)forvoltages. 12 SubmitDocumentationFeedback Copyright©2007–2013,TexasInstrumentsIncorporated ProductFolderLinks:LM20123

LM20123 www.ti.com SNVS524E–OCTOBER2007–REVISEDMARCH2013 LM20123 L VIN PVIN SW VOUT CIN RF EANVIN FB RFB1 COUT CF VIN RFB2 RPG PGOOD VPG COMP VCC RC1 SS/TRK CC1 PGND GND CSS CVCC Figure25. TypicalApplicationCircuit The first equation to calculate for any buck converter is duty-cycle. Ignoring conduction losses associated with theFETsandparasiticresistancesitcanbeapproximatedby: VOUT D = VIN (2) INDUCTORSELECTION(L) Theinductorvalueisdeterminedbasedontheoperatingfrequency,loadcurrent,ripplecurrent,anddutycycle. The inductor selected should have a saturation current rating greater than the peak current limit of the device. Keep in mind the specified current limit does not account for delay of the current limit comparator, therefore the current limit in the application may be higher than the specified value. To optimize the performance and prevent the device from entering current limit at maximum load, the inductance is typically selected such that the ripple current, Δi , is less than 30% of the rated output current. Figure 26, shown below illustrates the switch and L inductorripplecurrentwaveforms.Oncetheinputvoltage,outputvoltage,operatingfrequency,anddesiredripple currentareknown,theminimumvaluefortheinductorcanbecalculatedbytheformulashownbelow: (VIN - VOUT) x D LMIN = ’iL x fSW (3) VSW VIN Time IL IL AVG = IOUT ’IL Time Figure26. SwitchandInductorCurrentWaveforms If needed, slightly smaller value inductors can be used, however, the peak inductor current, I + Δi /2, should OUT L be kept below the peak current limit of the device. In general, the inductor ripple current, Δi , should be greater L than 10% of the rated output current to provide adequate current sense information for the current mode control loop. If the ripple current in the inductor is too low, the control loop will not have sufficient current sense informationandcanbepronetoinstability. Copyright©2007–2013,TexasInstrumentsIncorporated SubmitDocumentationFeedback 13 ProductFolderLinks:LM20123

LM20123 SNVS524E–OCTOBER2007–REVISEDMARCH2013 www.ti.com OUTPUTCAPACITORSELECTION(C ) OUT The output capacitor, C , filters the inductor ripple current and provides a source of charge for transient load OUT conditions.AwiderangeofoutputcapacitorsmaybeusedwiththeLM20123thatprovideexcellentperformance. The best performance is typically obtained using ceramic, SP, or OSCON type chemistries. Typical trade-offs are that the ceramic capacitor provides extremely low ESR to reduce the output ripple voltage and noise spikes, while the SP and OSCON capacitors provide a large bulk capacitance in a small volume for transient loading conditions. When selecting the value for the output capacitor the two performance characteristics to consider are the output voltagerippleandtransientresponse.Theoutputvoltageripplecanbeapproximatedbyusingtheformulashown below. 1 ’VOUT = ’iL x RESR +8 x fSW x COUT where • ΔV (V)istheamountofpeaktopeakvoltagerippleatthepowersupplyoutput OUT • R (Ω)istheseriesresistanceoftheoutputcapacitor ESR • f (Hz)istheswitchingfrequency SW • C (F)istheoutputcapacitanceusedinthedesign (4) OUT Theamountofoutputripplethatcanbetoleratedisapplicationspecific;howeverageneralrecommendationisto keep the output ripple less than 1% of the rated output voltage. Keep in mind ceramic capacitors are sometimes preferred because they have very low ESR; however, depending on package and voltage rating of the capacitor the value of the capacitance can drop significantly with applied voltage. The output capacitor selection will also affect the output voltage droop during a load transient. The peak droop on the output voltage during a load transient is dependent on many factors; however, an approximation of the transient droop ignoring loop bandwidthcanbeobtainedusingthefollowingequation. L x ’I 2 V = ’I x R + OUTSTEP DROOP OUTSTEP ESR C x (V - V ) OUT IN OUT where • C (F)istheminimumrequiredoutputcapacitance OUT • L(H)isthevalueoftheinductor • V (V)istheoutputvoltagedropignoringloopbandwidthconsiderations DROOP • ΔI (A)istheloadstepchange OUTSTEP • R (Ω)istheoutputcapacitorESR ESR • V (V)istheinputvoltage IN • V (V)isthesetregulatoroutputvoltage (5) OUT Both the tolerance and voltage coefficient of the capacitor needs to be examined when designing for a specific outputrippleortransientdroptarget. INPUTCAPACITORSELECTION(C ) IN Good quality input capacitors are necessary to limit the ripple voltage at the VIN pin while supplying most of the switch current during the on-time. In general it is recommended to use a ceramic capacitor for the input as they provide both a low impedance and small footprint. One important note is to use a good dielectric for the ceramic capacitorsuchasX5RorX7R.TheseprovidebetterovertemperatureperformanceandminimizetheDCvoltage derating that occurs on Y5V capacitors. For many applications, a 22 µF, X5R, 6.3V input capacitor is sufficient; however, additional capacitance may be required if the connection to the input supply bulk is far from the PVIN pins.TheinputcapacitorshouldbeplacedascloseaspossiblePVINandPGNDpinsofthedevice. Non-ceramic input capacitors should be selected for RMS current rating and minimum ripple voltage. A good approximationfortherequiredripplecurrentratingisgivenbytherelationship: IIN-RMS = IOUT D(1 - D) (6) 14 SubmitDocumentationFeedback Copyright©2007–2013,TexasInstrumentsIncorporated ProductFolderLinks:LM20123

LM20123 www.ti.com SNVS524E–OCTOBER2007–REVISEDMARCH2013 As indicated by the RMS ripple current equation, highest requirement for RMS current rating occurs at 50% duty cycle. For this case, the RMS ripple current rating of the input capacitor should be greater than half the output current. For best performance, low ESR ceramic capacitors should be placed in parallel with higher capacitance capacitorstoprovidethebestinputfilteringforthedevice. SETTINGTHEOUTPUTVOLTAGE(R ,R ) FB1 FB2 TheresistorsR andR areselectedtosettheoutputvoltageforthedevice.Table1,shownbelow,provides FB1 FB2 suggestionsforR andR forcommonoutputvoltages. FB1 FB2 Table1.SuggestedValuesforR andR FB1 FB2 R (kΩ) R (kΩ) V FB1 FB2 OUT short open 0.8 4.99 10 1.2 8.87 10.2 1.5 12.7 10.2 1.8 21.5 10.2 2.5 31.6 10.2 3.3 If different output voltages are required, R should be selected to be between 4.99 kΩ to 49.9 kΩ and R can FB2 FB1 becalculatedusingtheequationbelow. V OUT RFB1 = - 1 x RFB2 0.8 (7) LOOPCOMPENSATION(R ,C ) C1 C1 The purpose of loop compensation is to meet static and dynamic performance requirements while maintaining adequate stability. Optimal loop compensation depends on the output capacitor, inductor, load, and the device itself. Table 2 below gives values for the compensation network that will result in a stable system when using a 100µF,6.3VceramicX5Routputcapacitorand1µHinductor. Table2.RecommendedCompensationfor C =100µFandL=1µH OUT V V C (nF) R (kΩ) IN OUT C1 C1 5.00 3.30 4.7 17.86 5.00 2.50 4.7 12.93 5.00 1.80 4.7 8.81 5.00 1.50 4.7 7 5.00 1.20 4.7 3.96 5.00 0.80 4.7 1.79 3.30 2.50 4.7 12.24 3.30 1.80 4.7 11.24 3.30 1.50 4.7 7.94 3.30 1.20 4.7 6.03 3.30 0.80 4.7 1.793 If the desired solution differs from the table above the loop transfer function should be analyzed to optimize the loopcompensation.Theoveralllooptransferfunctionistheproductofthepowerstageandthefeedbacknetwork transfer functions. For stability purposes, the objective is to have a loop gain slope that is -20db/decade from a very low frequency to beyond the crossover frequency. Figure 27, shown below, shows the transfer functions for powerstage,feedback/compensationnetwork,andtheresultingclosedloopsystemfortheLM20123. Copyright©2007–2013,TexasInstrumentsIncorporated SubmitDocumentationFeedback 15 ProductFolderLinks:LM20123

LM20123 SNVS524E–OCTOBER2007–REVISEDMARCH2013 www.ti.com er Filt Output Filter Pole, fP(FIL) ut on AM Outpuncti 0 dB or and nsfer F Output Filter Zero, fZ(FIL) ulatTra d o Complex Double Pole, fP(MOD) M Error Amp Pole, fP1(EA) N (dB) AEA OptPioonlea,l EfPr2ro(Er AA)mp mplifier Function GAI 0 dB or Asfer Error Amp Zero, fZ(EA) Erran Tr AEA + AM Error Amp Pole, fP(EA) osed nction Clu ed er F 0 dB atsf sn na peTr Complex Double Pole, fP(MOD) omop Co L fC fSW/2 FREQUENCY (Hz) Figure27. LM20123LoopCompensation The power stage transfer function is dictated by the modulator, output LC filter, and load; while the feedback transferfunctionissetbythefeedbackresistorratio,errorampgain,andexternalcompensationnetwork. To achieve a -20dB/decade slope, the error amplifier zero, located at f , should positioned to cancel the Z(EA) output filter pole (f ). An additional error amp pole, located at f , can be added to cancel the output filter P(FIL) P2(EA) zero at f . Cancellation of the output filter zero is recommended if larger value, non-ceramic output capacitors Z(FIL) areused. CompensationoftheLM20123isachievedbyaddinganRCnetworkasshowninFigure28below. LM20123 COMP RC1 CC2 (optional) CC1 Figure28. CompensationNetworkforLM20123 A good starting value for C for most applications is 4.7 nF. Once the value of C is chosen the value of R C1 C1 C1 shouldbecalculatedusingtheequationbelowtocanceltheoutputfilterpole(f )asshowninFigure27. P(FIL) -1 C I 1-D 22 x D R = C1 x OUT + + C1 C V f x L V OUT OUT SW IN (8) 16 SubmitDocumentationFeedback Copyright©2007–2013,TexasInstrumentsIncorporated ProductFolderLinks:LM20123

LM20123 www.ti.com SNVS524E–OCTOBER2007–REVISEDMARCH2013 A higher crossover frequency can be obtained, usually at the expense of phase margin, by lowering the value of C and recalculating the value of R . Likewise, increasing C and recalculating R will provide additional C1 C1 C1 C1 phase margin at a lower crossover frequency. As with any attempt to compensate the LM20123 the stability of thesystemshouldbeverifiedfordesiredtransientdroopandsettlingtime. If the output filter zero, f approaches the crossover frequency (f ), an additional capacitor (C ) should be Z(FIL) C C2 placed at the COMP pin to ground. This capacitor adds a pole to cancel the output filter zero assuring the crossover frequency will occur before the double pole at f /2 degrades the phase margin. The output filter zero SW issetbytheoutputcapacitorvalueandESRasshownintheequationbelow. 1 fZ(FIL) =2 x S x COUT x RESR (9) Ifneeded,thevalueforC shouldbecalculatedusingtheequationshownbelow. C2 COUT x RESR CC2 = RC1 where • R istheoutputcapacitorseriesresistance ESR • R isthecalculatedcompensationresistance (10) C1 AVINFILTERINGCOMPONENTS(C andR ) F F To prevent high frequency noise spikes from disturbing the sensitive analog circuitry connected to the AVIN and AGND pins, a high frequency RC filter is required between PVIN and AVIN. These components are shown in Figure 25. as C and R . The required value for R is 1Ω. C must be used. Recommended value of C is 1.0 F F F F F µF. The filter capacitor, C should be placed as close to the IC as possible with a direct connection from AVIN to F AGND.AgoodqualityX5RorX7RceramiccapacitorshouldbeusedforC . F SUB-REGULATORBYPASSCAPACITOR(C ) VCC The capacitor at the VCC pin provides noise filtering and stability for the internal sub-regulator. The recommendedvalueofC shouldbenosmallerthan1µFandnogreaterthan10µF.Thecapacitorshouldbe VCC a good quality ceramic X5R or X7R capacitor. In general, a 1 µF ceramic capacitor is recommended for most applications. SETTINGTHESTARTUPTIME(C ) SS The addition of a capacitor connected from the SS pin to ground sets the time at which the output voltage will reach the final regulated value. Larger values for C will result in longer start up times. Table 3, shown below SS providesalistofsoftstartcapacitorsandthecorrespondingtypicalstartuptimes. Table3.StartUpTimesforDifferentSoft-StartCapacitors StartUpTime(ms) C (nF) SS 1 none 5 33 10 68 15 100 20 120 Ifdifferentstartuptimesareneededtheequationshownbelowcanbeusedtocalculatethestartuptime. 0.8V x C t = SS SS ISS (11) Asshownabove,thestartuptimeisinfluencedbythevalueoftheSoft-StartcapacitorC (F)andthe5µASoft- SS StartpincurrentI (A).thatmaybefoundintheelectricalcharacteristicstable. SS Copyright©2007–2013,TexasInstrumentsIncorporated SubmitDocumentationFeedback 17 ProductFolderLinks:LM20123

LM20123 SNVS524E–OCTOBER2007–REVISEDMARCH2013 www.ti.com While the Soft-Start capacitor can be sized to meet many start up requirements, there are limitations to its size. The Soft-Start time can never be faster than 1 ms due to the internal default 1 ms start up time. When the device is enabled there is an approximate time interval of 50 µs when the Soft-Start capacitor will be discharged just priortotheSoft-Startramp.IftheenablepinisrapidlypulsedortheSoft-Startcapacitorislargetheremaynotbe enough time for C to completely discharge resulting in start up times less than predicted. To aid in discharging SS the Soft-Start capacitor during long disable periods an external 1 MΩ resistor from SS/TRK to ground can be usedwithoutgreatlyaffectingthestart-uptime. USINGPRECISIONENABLEANDPOWERGOOD The precision enable (EN) and power good (PGOOD) pins of the LM20123 can be used to address many sequencing requirements. The turn-on of the LM20123 can be controlled with the precision enable pin by using twoexternalresistorsasshowninFigure29. External VOUT1 Power Supply RA LM20123 VOUT2 EN RB Figure29. SequencingLM20123withPrecisionEnable The value for resistor R can be selected by the user to control the current through the divider. Typically this B resistor will be selected to be between 10 kΩ and 1 MΩ. Once the value for R is chosen the resistor R can be B A solvedusingtheequationbelowtosetthedesiredturn-onvoltage. V RA = V TO - 1 x RB IH_EN (12) When designing for a specific turn-on threshold (V ) the tolerance on the input supply, enable threshold TO (V ),andexternalresistorsneedstobeconsideredtoinsureproperturn-onofthedevice. IH_EN The LM20123 features an open drain power good (PGOOD) pin to sequence external supplies or loads and to provide fault detection. This pin requires an external resistor (R ) to pull PGOOD high while when the output is PG withinthePGOODtolerancewindow.Typicalvaluesforthisresistorrangefrom10kΩto100kΩ. TRACKINGANEXTERNALSUPPLY By using a properly chosen resistor divider network connected to the SS/TRK pin, as shown in Figure 30, the output of the LM20123 can be configured to track an external voltage source to obtain a simultaneous or ratiometricstartup. External VOUT1 Power Supply EN R1 LM20123 VOUT2 SS/TRK R2 Figure30. TrackinganExternalSupply Since the Soft-Start charging current I is always present on the SS/TRK pin, the size of R2 should be less than SS 10 kΩ to minimize the errors in the tracking output. Once a value for R2 is selected the value for R1 can be calculated using appropriate equation in Figure 31, to give the desired start up. Figure 31 shows two common start up sequences; the top waveform shows a simultaneous start up while the waveform at the bottom illustrates aratiometricstartup. 18 SubmitDocumentationFeedback Copyright©2007–2013,TexasInstrumentsIncorporated ProductFolderLinks:LM20123

LM20123 www.ti.com SNVS524E–OCTOBER2007–REVISEDMARCH2013 SIMULTANEOUS START UP VOUT1 AGE VOUT2 R1=¤§¤VOUT2-1‚•‚xR2 LT ' 0.8V „ O V VEN V <0.8xV OUT2 OUT1 TIME RATIOMETRIC START UP VOUT1 VOUT2 R1=(VOUT1-1)xR2 E G A T L O V VEN TIME Figure31. CommonStartUpSequences A simultaneous start up is preferred when powering most FPGAs, DSPs, or other microprocessors. In these systems the higher voltage, V , usually powers the I/O, and the lower voltage, V , powers the core. A OUT1 OUT2 simultaneous start up provides a more robust power up for these applications since it avoids turning on any parasiticconductionpathsthatmayexistbetweenthecoreandtheI/Opinsoftheprocessor. The second most common power on behavior is known as a ratiometric start up. This start up is preferred in applicationswherebothsuppliesneedtobeatthefinalvalueatthesametime. Similar to the Soft-Start function, the fastest start up possible is 1ms regardless of the rise time of the tracking voltage. When using the track feature the final voltage seen by the SS/TRACK pin should exceed 1V to provide sufficientoverdriveandtransientimmunity. Copyright©2007–2013,TexasInstrumentsIncorporated SubmitDocumentationFeedback 19 ProductFolderLinks:LM20123

LM20123 SNVS524E–OCTOBER2007–REVISEDMARCH2013 www.ti.com THERMALCONSIDERATIONS The thermal characteristics of the LM20123 are specified using the parameter θ , which relates the junction JA temperature to the ambient temperature. Although the value of θ is dependent on many variables, it still can be JA usedtoapproximatetheoperatingjunctiontemperatureofthedevice. Toobtainanestimateofthedevicejunctiontemperature,onemayusethefollowingrelationship: T =P θ +T (13) J D JA A and P =P x(1-Efficiency)-1.1xI 2xDCR D IN OUT where • T isthejunctiontemperaturein°C J • P istheinputpowerinWatts(P =V xI ) IN IN IN IN • θ isthejunctiontoambientthermalresistancefortheLM20123 JA • T istheambienttemperaturein°C A • I istheoutputloadcurrent OUT • DCRistheinductorseriesresistance (14) It is important to always keep the operating junction temperature (T ) below 125°C for reliable operation. If the J junction temperature exceeds 160°C the device will cycle in and out of thermal shutdown. If thermal shutdown occursitisasignofinadequateheatsinkingorexcessivepowerdissipationinthedevice. Figure 32., shown below, provides a better approximation of the θ for a given PCB copper area. The PCB JA heatsink area consists of 2oz. copper located on the bottom layer of the PCB directly under the HTSSOP exposed pad. The bottom copper area is connected to the HTSSOP exposed pad by means of a 4 x 4 array of 12milthermalvias. Figure32. ThermalResistancevsPCBArea 20 SubmitDocumentationFeedback Copyright©2007–2013,TexasInstrumentsIncorporated ProductFolderLinks:LM20123

LM20123 www.ti.com SNVS524E–OCTOBER2007–REVISEDMARCH2013 PCBLAYOUTCONSIDERATIONS PC board layout is an important part of DC-DC converter design. Poor board layout can disrupt the performance of a DC-DC converter and surrounding circuitry by contributing to EMI, ground bounce, and resistive voltage loss inthetraces.ThesecansenderroneoussignalstotheDC-DCconverterresultinginpoorregulationorinstability. Goodlayoutcanbeimplementedbyfollowingafewsimpledesignrules. 1. Minimize area of switched current loops. In a buck regulator there are two loops where currents are switched very fast. The first loop starts from the input capacitor, to the regulator VIN pin, to the regulator SW pin, to the inductor then out to the output capacitor and load. The second loop starts from the output capacitor ground, to the regulator PGND pins, to the inductor and then out to the load (see Figure 33). To minimize both loop areas the input capacitor should be placed as close as possible to the PVIN pin. Grounding for both the input and output capacitor should consist of a small localized top side plane that connects to PGND and the die attach pad (DAP). The inductor should be placed as close as possible to the SW pin and output capacitor 2. Minimize the copper area of the switch node. Since the LM20123 has the SW pins on opposite sides of the package it is recommended to via these pins down to the bottom or internal layer with 2 to 4 vias on each SW pin. The SW pins should be directly connected with a trace that runs across the bottom of the package. To minimize IR losses this trace should be no smaller that 50 mils wide, but no larger than 100 mils wide to keepthecopperareatoaminimum.IngeneraltheSWpinsshouldnotbeconnectedonthetoplayersinceit could block the ground return path for the power ground. The inductor should be placed as close as possible tooneoftheSWpinstofurtherminimizethecopperareaoftheswitchnode. 3. Have a single point ground for all device analog grounds located under the DAP. The ground connections for the compensation, feedback, and Soft-Start components should be connected together then routed to the AGND pin of the device. The AGND pin should connect to PGND under the DAP. This prevents any switched or load currents from flowing in the analog ground plane. If not properly handled poor grounding canresultindegradedloadregulationorerraticswitchingbehavior. 4. Minimize trace length to the FB pin. Since the feedback node can be high impedance the trace from the output resistor divider to FB pin should be as short as possible. This is most important when high value resistors are used to set the output voltage. The feedback trace should be routed away from the SW pin and inductortoavoidcontaminatingthefeedbacksignalwithswitchnoise. 5. Make input and output bus connections as wide as possible. This reduces any voltage drops on the input or output of the converter and can improve efficiency. If voltage accuracy at the load is important make sure feedback voltage sense is made at the load. Doing so will correct for voltage drops at the load and provide thebestoutputaccuracy. 6. Provide adequate device heatsinking. Use as many vias as is possible to connect the DAP to the power planeheatsink.Forbestresultsusea4x4viaarraywithaminimumviadiameterof12mils.SeetheThermal Considerations section to insure enough copper heatsinking area is used to keep the junction temperature below125°C. LM20123 L PVIN SW VOUT CIN COUT PGND LOOP1 LOOP2 Figure33. SchematicofLM20123HighlightingLayoutSensitiveNodes Copyright©2007–2013,TexasInstrumentsIncorporated SubmitDocumentationFeedback 21 ProductFolderLinks:LM20123

LM20123 SNVS524E–OCTOBER2007–REVISEDMARCH2013 www.ti.com Typical Application Circuit This section provides several application solutions with a bill of materials. All bill of materials reference the below figure. The compensation for these solutions were optimized to work over a wide range of input and output voltages; if a faster transient response is needed reduce the value of C and calculate the new value for R as C1 C1 outlineinthedesignguide. LM20123 L VIN PVIN SW VOUT RFB1 CIN RF EN FB COUT AVIN RFB2 PGOOD CF COMP VCC RC1 SS/TRK CVCC PGND AGND CC1 CSS (optional) Bill of Materials (V = 5V, V = 3.3V, I = 3A) IN OUT OUTMAX Designator Description PartNumber Manufacturer Qty U1 SynchronousBuckRegulator LM20123 TexasInstruments 1 C 47µF,1210,X5R,6.3V GRM32ER60J476ME20 Murata 1 IN C 47µF,1210,X5R,6.3V GRM32ER60J476ME20 Murata 1 OUT L 1.2µH,17mΩ DO1813H-122ML Coilcraft 1 R 1Ω,0603 CRCW06031R0J-e3 Vishay-Dale 1 F C 100nF,0603,X7R,16V GRM188R71C104KA01 Murata 1 F C 1µF,0603,X5R,6.3V GRM188R60J105KA01 Murata 1 VCC R 8.45kΩ,0603 CRCW06038451F-e3 Vishay-Dale 1 C1 C 1.5nF,0603,X7R,25V VJ0603Y152KXXA Vishay-Vitramon 1 C1 C 33nF,0603,X7R,25V VJ0603Y333KXXA Vishay-Vitramon 1 SS R 31.6kΩ,0603 CRCW06033162F-e3 Vishay-Dale 1 FB1 R 10.2kΩ,0603 CRCW06031022F-e3 Vishay-Dale 1 FB2 Bill of Materials (V = 3.3V to 5V, V = 1.2V, I = 3A) IN OUT OUTMAX Designator Description PartNumber Manufacturer Qty U1 SynchronousBuckRegulator LM20123 TexasInstrumentsn 1 C 47µF,1210,X5R,6.3V GRM32ER60J476ME20 Murata 1 IN C 47µF,1210,X5R,6.3V GRM32ER60J476ME20 Murata 1 OUT L 0.68µH,5mΩ IHLP2525CZER0R68M01 Vishay 1 R 1Ω,0603 CRCW06031R0J-e3 Vishay-Dale 1 F C 100nF,0603,X7R,16V GRM188R71C104KA01 Murata 1 F C 1µF,0603,X5R,6.3V GRM188R60J105KA01 Murata 1 VCC R 5.76kΩ,0603 CRCW06035761F-e3 Vishay-Dale 1 C1 C 2.2nF,0603,X7R,25V VJ0603Y222KXXA Vishay-Vitramon 1 C1 C 33nF,0603,X7R,25V VJ0603Y333KXXA Vishay-Vitramon 1 SS R 4.99kΩ,0603 CRCW06034991F-e3 Vishay-Dale 1 FB1 R 10kΩ,0603 CRCW06031002F-e3 Vishay-Dale 1 FB2 22 SubmitDocumentationFeedback Copyright©2007–2013,TexasInstrumentsIncorporated ProductFolderLinks:LM20123

LM20123 www.ti.com SNVS524E–OCTOBER2007–REVISEDMARCH2013 REVISION HISTORY ChangesfromRevisionD(March2013)toRevisionE Page • ChangedlayoutofNationalDataSheettoTIformat.......................................................................................................... 22 Copyright©2007–2013,TexasInstrumentsIncorporated SubmitDocumentationFeedback 23 ProductFolderLinks:LM20123

PACKAGE OPTION ADDENDUM www.ti.com 6-Feb-2020 PACKAGING INFORMATION Orderable Device Status Package Type Package Pins Package Eco Plan Lead/Ball Finish MSL Peak Temp Op Temp (°C) Device Marking Samples (1) Drawing Qty (2) (6) (3) (4/5) LM20123MH/NOPB ACTIVE HTSSOP PWP 16 92 Green (RoHS SN Level-1-260C-UNLIM -40 to 125 20123 & no Sb/Br) MH LM20123MHE/NOPB ACTIVE HTSSOP PWP 16 250 Green (RoHS SN Level-1-260C-UNLIM -40 to 125 20123 & no Sb/Br) MH LM20123MHX/NOPB ACTIVE HTSSOP PWP 16 2500 Green (RoHS SN Level-1-260C-UNLIM -40 to 125 20123 & no Sb/Br) MH (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) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may reference these types of products as "Pb-Free". RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption. Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of <=1000ppm threshold. Antimony trioxide based flame retardants must also meet the <=1000ppm threshold requirement. (3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. (4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device. (5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation of the previous line and the two combined represent the entire Device Marking for that device. (6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish value exceeds the maximum column width. 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. Addendum-Page 1

PACKAGE OPTION ADDENDUM www.ti.com 6-Feb-2020 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. Addendum-Page 2

PACKAGE MATERIALS INFORMATION www.ti.com 20-Jul-2019 TAPE AND REEL INFORMATION *Alldimensionsarenominal Device Package Package Pins SPQ Reel Reel A0 B0 K0 P1 W Pin1 Type Drawing Diameter Width (mm) (mm) (mm) (mm) (mm) Quadrant (mm) W1(mm) LM20123MHE/NOPB HTSSOP PWP 16 250 178.0 12.4 6.95 5.6 1.6 8.0 12.0 Q1 LM20123MHX/NOPB HTSSOP PWP 16 2500 330.0 12.4 6.95 5.6 1.6 8.0 12.0 Q1 PackMaterials-Page1

PACKAGE MATERIALS INFORMATION www.ti.com 20-Jul-2019 *Alldimensionsarenominal Device PackageType PackageDrawing Pins SPQ Length(mm) Width(mm) Height(mm) LM20123MHE/NOPB HTSSOP PWP 16 250 210.0 185.0 35.0 LM20123MHX/NOPB HTSSOP PWP 16 2500 367.0 367.0 35.0 PackMaterials-Page2

PACKAGE OUTLINE PWP0016A PowerPAD T M HTSSOP - 1.2 mm max height SCALE 2.400 PLASTIC SMALL OUTLINE C 6.6 TYP SEATING PLANE 6.2 A PIN 1 ID 0.1 C AREA 14X 0.65 16 1 5.1 2X 4.9 4.55 NOTE 3 8 9 0.30 4.5 16X B 0.19 4.3 0.1 C A B (0.15) TYP SEE DETAIL A 4X 0.166 MAX 2X 1.34 MAX NOTE 5 NOTE 5 THERMAL PAD 0.25 3.3 2.7 17 GAGE PLANE 1.2 MAX 0.15 0 - 8 0.05 0.75 0.50 DETAIL A 3.3 (1) TYPICAL 2.7 4214868/A 02/2017 PowerPAD is a trademark of Texas Instruments. NOTES: 1. All linear dimensions are in millimeters. Any dimensions in parenthesis are for reference only. Dimensioning and tolerancing per ASME Y14.5M. 2. This drawing is subject to change without notice. 3. This dimension does not include mold flash, protrusions, or gate burrs. Mold flash, protrusions, or gate burrs shall not exceed 0.15 mm per side. 4. Reference JEDEC registration MO-153. 5. Features may not be present. www.ti.com

EXAMPLE BOARD LAYOUT PWP0016A PowerPAD T M HTSSOP - 1.2 mm max height PLASTIC SMALL OUTLINE (3.4) NOTE 9 SOLDER MASK (3.3) DEFINED PAD 16X (1.5) SYMM SEE DETAILS 1 16 16X (0.45) (1.1) SYMM 17 TYP (3.3) (5) NOTE 9 14X (0.65) 8 9 ( 0.2) TYP VIA (1.1) TYP METAL COVERED (5.8) BY SOLDER MASK LAND PATTERN EXAMPLE EXPOSED METAL SHOWN SCALE:10X SOOPLEDNEINRG MASK METAL SMOELTDAELR U MNDAESRK SOOPLEDNEINRG MASK EXPOSED METAL EXPOSED METAL 0.05 MIN 0.05 MAX ALL AROUND ALL AROUND NON SOLDER MASK SOLDER MASK DEFINED DEFINED SOLDER MASK DETAILS PADS 1-16 4214868/A 02/2017 NOTES: (continued) 6. Publication IPC-7351 may have alternate designs. 7. Solder mask tolerances between and around signal pads can vary based on board fabrication site. 8. This package is designed to be soldered to a thermal pad on the board. For more information, see Texas Instruments literature numbers SLMA002 (www.ti.com/lit/slma002) and SLMA004 (www.ti.com/lit/slma004). 9. Size of metal pad may vary due to creepage requirement. www.ti.com

EXAMPLE STENCIL DESIGN PWP0016A PowerPAD T M HTSSOP - 1.2 mm max height PLASTIC SMALL OUTLINE (3.3) BASED ON 0.125 THICK 16X (1.5) STENCIL (R0.05) TYP 1 16 16X (0.45) SYMM 17 (3.3) BASED ON 0.125 THICK STENCIL 14X (0.65) 9 8 SYMM METAL COVERED BY SOLDER MASK SEE TABLE FOR DIFFERENT OPENINGS (5.8) FOR OTHER STENCIL THICKNESSES SOLDER PASTE EXAMPLE EXPOSED PAD 100% PRINTED SOLDER COVERAGE BY AREA SCALE:10X STENCIL SOLDER STENCIL THICKNESS OPENING 0.1 3.69 X 3.69 0.125 3.3 X 3.3 (SHOWN) 0.15 3.01 X 3.01 0.175 2.79 X 2.79 4214868/A 02/2017 NOTES: (continued) 10. Laser cutting apertures with trapezoidal walls and rounded corners may offer better paste release. IPC-7525 may have alternate design recommendations. 11. Board assembly site may have different recommendations for stencil design. www.ti.com

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