Product Sample & Technical Tools & Support & Folder Buy Documents Software Community LM2736 SNVS316H–SEPTEMBER2004–REVISEDDECEMBER2014 LM2736 Thin SOT 750 mA Load Step-Down DC-DC Regulator 1 Features 3 Description • ThinSOT-6Package TheLM2736regulatorisamonolithic,highfrequency, 1 PWM step-down DC/DC converter in a 6-pin Thin • 3.0Vto18VInputVoltageRange SOT package. It provides all the active functions to • 1.25Vto16VOutputVoltageRange provide local DC/DC conversion with fast transient • 750mAOutputCurrent response and accurate regulation in the smallest possiblePCBarea. • 550kHz(LM2736Y)and1.6MHz(LM2736X) SwitchingFrequencies With a minimum of external components and online design support through WEBENCH®, the LM2736 is • 350mΩNMOSSwitch easy to use. The ability to drive 750 mA loads with an • 30nAShutdownCurrent internal 350 mΩ NMOS switch using state-of-the-art • 1.25V,2%InternalVoltageReference 0.5 µm BiCMOS technology results in the best power • InternalSoft-Start density available. The world class control circuitry allows for on-times as low as 13 ns, thus supporting • Current-Mode,PWMOperation exceptionally high frequency conversion over the • WEBENCH®OnlineDesignTool entire 3 V to 18 V input operating range down to the • ThermalShutdown minimum output voltage of 1.25 V. Switching frequency is internally set to 550 kHz (LM2736Y) or 2 Applications 1.6 MHz (LM2736X), allowing the use of extremely small surface mount inductors and chip capacitors. • LocalPointofLoadRegulation Even though the operating frequencies are very high, • CorePowerinHDDs efficiencies up to 90% are easy to achieve. External • Set-TopBoxes shutdown is included, featuring an ultra-low stand-by current of 30 nA. The LM2736 utilizes current-mode • BatteryPoweredDevices control and internal compensation to provide high- • USBPoweredDevices performance regulation over a wide range of • DSLModems operating conditions. Additional features include internal soft-start circuitry to reduce inrush current, • NotebookComputers pulse-by-pulse current limit, thermal shutdown, and outputover-voltageprotection. DeviceInformation(1) PARTNUMBER PACKAGE BODYSIZE(NOM) LM2736 SOT(6) 2.90mmx1.60mm (1) For all available packages, see the orderable addendum at theendofthedatasheet. TypicalApplicationCircuit Efficiencyvs.LoadCurrent "X" V =5V,V =3.3V IN OUT D2 VIN VIN BOOST C1 C3 L1 SW VOUT ON D1 C2 EN OFF R1 FB GND R2 1 An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications, intellectualpropertymattersandotherimportantdisclaimers.PRODUCTIONDATA.

LM2736 SNVS316H–SEPTEMBER2004–REVISEDDECEMBER2014 www.ti.com Table of Contents 1 Features.................................................................. 1 7.4 DeviceFunctionalModes........................................10 2 Applications........................................................... 1 8 ApplicationandImplementation........................ 11 3 Description............................................................. 1 8.1 ApplicationInformation ..........................................11 4 RevisionHistory..................................................... 2 8.2 TypicalApplications ...............................................13 5 PinConfigurationandFunctions......................... 3 9 PowerSupplyRecommendations...................... 27 6 Specifications......................................................... 4 10 Layout................................................................... 27 6.1 AbsoluteMaximumRatings......................................4 10.1 LayoutGuidelines.................................................27 6.2 ESDRatings ............................................................4 10.2 LayoutExample....................................................28 6.3 RecommendedOperatingConditions.......................4 11 DeviceandDocumentationSupport................. 29 6.4 ThermalInformation..................................................4 11.1 DeviceSupport......................................................29 6.5 ElectricalCharacteristics...........................................5 11.2 DocumentationSupport........................................29 6.6 TypicalCharacteristics..............................................6 11.3 Trademarks...........................................................29 7 DetailedDescription.............................................. 8 11.4 ElectrostaticDischargeCaution............................29 7.1 Overview...................................................................8 11.5 Glossary................................................................29 7.2 FunctionalBlockDiagram.........................................9 12 Mechanical,Packaging,andOrderable Information........................................................... 29 7.3 FeatureDescription...................................................9 4 Revision History NOTE:Pagenumbersforpreviousrevisionsmaydifferfrompagenumbersinthecurrentversion. ChangesfromRevisionG(October2014)toRevisionH Page • UpdatedDesignRequirementsandmovedBillofMaterialstoDetailedDesignProcedures.............................................. 13 ChangesfromRevisionF(April2013)toRevisionG Page • AddedESDRatingstable,FeatureDescriptionsection,DeviceFunctionalModes,ApplicationandImplementation section,PowerSupplyRecommendationssection,Layoutsection,DeviceandDocumentationSupportsection,and Mechanical,Packaging,andOrderableInformationsection.................................................................................................. 4 2 SubmitDocumentationFeedback Copyright©2004–2014,TexasInstrumentsIncorporated ProductFolderLinks:LM2736

LM2736 www.ti.com SNVS316H–SEPTEMBER2004–REVISEDDECEMBER2014 5 Pin Configuration and Functions PackageDDC(R-PDSO-G6) 6-LeadSOT TopView BOOST 1 6 SW GND 2 5 VIN FB 3 4 EN PinFunctions PIN I/O DESCRIPTION NAME NO. BoostvoltagethatdrivestheinternalNMOScontrolswitch.Abootstrapcapacitoris BOOST 1 I connectedbetweentheBOOSTandSWpins. SignalandPowergroundpin.Placethebottomresistorofthefeedbacknetworkascloseas GND 2 GND possibletothispinforaccurateregulation. FB 3 I Feedbackpin.ConnectFBtotheexternalresistordividertosetoutputvoltage. Enablecontrolinput.Logichighenablesoperation.Donotallowthispintofloatorbegreater EN 4 I thanV +0.3V. IN V 5 I Inputsupplyvoltage.Connectabypasscapacitortothispin. IN SW 6 O Outputswitch.Connectstotheinductor,catchdiode,andbootstrapcapacitor. Copyright©2004–2014,TexasInstrumentsIncorporated SubmitDocumentationFeedback 3 ProductFolderLinks:LM2736

LM2736 SNVS316H–SEPTEMBER2004–REVISEDDECEMBER2014 www.ti.com 6 Specifications 6.1 Absolute Maximum Ratings overoperatingfree-airtemperaturerange(unlessotherwisenoted)(1) MIN MAX UNIT V -0.5 22 V IN SWVoltage -0.5 22 V BoostVoltage -0.5 28 V BoosttoSWVoltage -0.5 8 V FBVoltage -0.5 3 V ENVoltage -0.5 V +0.3 V IN JunctionTemperature 150 °C Soldering Infrared/ConvectionReflow(15sec) 220 °C Information WaveSolderingLeadtemperature(10sec) 260 °C T Storagetemperature -65 150 °C stg (1) IfMilitary/Aerospacespecifieddevicesarerequired,pleasecontacttheTexasInstrumentsSalesOffice/Distributorsforavailabilityand specifications. 6.2 ESD Ratings VALUE UNIT Humanbodymodel(HBM), V(ESD) Electrostaticdischarge perANSI/ESDA/JEDECJS-001,allpins(1) ±2000 V (1) JEDECdocumentJEP155statesthat500-VHBMallowssafemanufacturingwithastandardESDcontrolprocess. 6.3 Recommended Operating Conditions overoperatingfree-airtemperaturerange(unlessotherwisenoted) MIN NOM MAX UNIT V 3 18 V IN SWVoltage -0.5 18 V BoostVoltage -0.5 23 V BoosttoSWVoltage 1.6 5.5 V JunctionTemperatureRange −40 125 °C 6.4 Thermal Information LM2736 THERMALMETRIC(1) DDC UNIT 6PINS R (2) Junction-to-ambientthermalresistance 158.1 θJA R Junction-to-case(top)thermalresistance 46.5 θJC(top) R Junction-to-boardthermalresistance 29.5 θJB °C/W ψ Junction-to-topcharacterizationparameter 0.8 JT ψ Junction-to-boardcharacterizationparameter 29.2 JB R Junction-to-case(bottom)thermalresistance n/a θJC(bot) (1) Formoreinformationabouttraditionalandnewthermalmetrics,seetheICPackageThermalMetricsapplicationreport,SPRA953. (2) Thermalshutdownwilloccurifthejunctiontemperatureexceeds165°C.ThemaximumpowerdissipationisafunctionofT ,θ J(MAX) JA andT .ThemaximumallowablepowerdissipationatanyambienttemperatureisP =(T –T )/θ .Allnumbersapplyfor A D J(MAX) A JA packagessoldereddirectlyontoa3”x3”PCboardwith2oz.copperon4layersinstillair.Fora2layerboardusing1oz.copperinstill air,θ =204°C/W. JA 4 SubmitDocumentationFeedback Copyright©2004–2014,TexasInstrumentsIncorporated ProductFolderLinks:LM2736

LM2736 www.ti.com SNVS316H–SEPTEMBER2004–REVISEDDECEMBER2014 6.5 Electrical Characteristics SpecificationswithstandardtypefaceareforT =25°Cunlessotherwisespecified.Datasheetmin/maxspecificationlimitsare J ensuredbydesign,test,orstatisticalanalysis. T =25°C TJ=-40°Cto125°C J PARAMETER TESTCONDITIONS UNIT MIN(1) TYP(2) MAX(1) MIN TYP MAX V FeedbackVoltage 1.250 1.225 1.275 V FB ΔV /Δ FeedbackVoltageLine V =3Vto18V FB IN 0.01 %/V V Regulation IN FeedbackInputBias I Sink/Source 10 250 nA FB Current UndervoltageLockout V Rising 2.74 2.90 IN UVLO UndervoltageLockout V Falling 2.3 2.0 V IN UVLOHysteresis 0.44 0.30 0.62 LM2736X 1.6 1.2 1.9 F SwitchingFrequency MHz SW LM2736Y 0.55 0.40 0.66 LM2736X 92% 85% D MaximumDutyCycle MAX LM2736Y 96% 90% LM2736X 2% D MinimumDutyCycle MIN LM2736Y 1% R SwitchONResistance V -V =3V 350 650 mΩ DS(ON) BOOST SW I SwitchCurrentLimit V -V =3V 1.5 1.0 2.3 A CL BOOST SW I QuiescentCurrent Switching 1.5 2.5 mA Q QuiescentCurrent V =0V EN 30 nA (shutdown) LM2736X(50%Duty 2.2 3.3 Cycle) I BoostPinCurrent mA BOOST LM2736Y(50%Duty 0.9 1.6 Cycle) ShutdownThreshold V Falling EN 0.4 Voltage V V EN_TH EnableThreshold V Rising 1.8 EN Voltage I EnablePinCurrent Sink/Source 10 nA EN I SwitchLeakage 40 nA SW (1) SpecifiedtoTexasInstruments'AverageOutgoingQualityLevel(AOQL). (2) Typicalsrepresentthemostlikelyparametricnorm. Copyright©2004–2014,TexasInstrumentsIncorporated SubmitDocumentationFeedback 5 ProductFolderLinks:LM2736

LM2736 SNVS316H–SEPTEMBER2004–REVISEDDECEMBER2014 www.ti.com 6.6 Typical Characteristics AllcurvestakenatV =5V,V -V =5V,L1=4.7µH("X"),L1=10µH("Y"),andT =25°C,unlessspecified IN BOOST SW A otherwise. Figure1.OscillatorFrequencyvsTemperature-"X" Figure2.OscillatorFrequencyvsTemperature-"Y" Figure3.CurrentLimitvsTemperature Figure4.V vsTemperature FB Figure5.R vsTemperature Figure6.I SwitchingvsTemperature DSON Q 6 SubmitDocumentationFeedback Copyright©2004–2014,TexasInstrumentsIncorporated ProductFolderLinks:LM2736

LM2736 www.ti.com SNVS316H–SEPTEMBER2004–REVISEDDECEMBER2014 Typical Characteristics (continued) AllcurvestakenatV =5V,V -V =5V,L1=4.7µH("X"),L1=10µH("Y"),andT =25°C,unlessspecified IN BOOST SW A otherwise. Figure7.LineRegulation-"X" Figure8.LineRegulation-"Y" V =3.3V,I =500mA V =3.3V,I =500mA OUT OUT OUT OUT Figure9.LineRegulation-"X" Figure10.LineRegulation-"Y" Copyright©2004–2014,TexasInstrumentsIncorporated SubmitDocumentationFeedback 7 ProductFolderLinks:LM2736

LM2736 SNVS316H–SEPTEMBER2004–REVISEDDECEMBER2014 www.ti.com 7 Detailed Description 7.1 Overview The LM2736 device is a constant frequency PWM buck regulator IC that delivers a 750 mA load current. The regulator has a preset switching frequency of either 550 kHz (LM2736Y) or 1.6 MHz (LM2736X). These high frequencies allow the LM2736 device to operate with small surface mount capacitors and inductors, resulting in DC/DC converters that require a minimum amount of board space. The LM2736 device is internally compensated, so it is simple to use, and requires few external components. The LM2736 device uses current- modecontroltoregulatetheoutputvoltage. The following operating description of the LM2736 device will refer to the Simplified Block Diagram (Functional Block Diagram) and to the waveforms in Figure 11. The LM2736 device supplies a regulated output voltage by switching the internal NMOS control switch at constant frequency and variable duty cycle. A switching cycle begins at the falling edge of the reset pulse generated by the internal oscillator. When this pulse goes low, the output control logic turns on the internal NMOS control switch. During this on-time, the SW pin voltage (V ) SW swings up to approximately V , and the inductor current (I ) increases with a linear slope. I is measured by the IN L L current-sense amplifier, which generates an output proportional to the switch current. The sense signal is summed with the regulator’s corrective ramp and compared to the error amplifier’s output, which is proportional to the difference between the feedback voltage and V . When the PWM comparator output goes high, the REF output switch turns off until the next switching cycle begins. During the switch off-time, inductor current discharges through Schottky diode D1, which forces the SW pin to swing below ground by the forward voltage (V )ofthecatchdiode.Theregulatorloopadjuststhedutycycle(D)tomaintainaconstantoutputvoltage. D VSW D = TON/TSW VIN SW Voltage TON TOFF 0 VD t TSW IL IPK Inductor Current 0 t Figure11. LM2736WaveformsofSWPinVoltageandInductorCurrent 8 SubmitDocumentationFeedback Copyright©2004–2014,TexasInstrumentsIncorporated ProductFolderLinks:LM2736

LM2736 www.ti.com SNVS316H–SEPTEMBER2004–REVISEDDECEMBER2014 7.2 Functional Block Diagram VIN VIN Current-Sense Amplifier ONEN RIengateunrldantaolr +- RSENSE D2 CIN Enable OFF Circuit Thermal Shutdown BOOST VBOOST Under LVoocltkaoguet Output Driver 0.3: CBOOST CLuirmreitnt CLoongtircol Switch SW VSW L VOUT OVP Oscillator Reset Comparator D1 IL COUT Pulse - 1.375V + + PWM - R1 Comparator ISENSE + - FB + Internal - + Error Compensation + Corrective Ramp Signal + VREF R2 Error Amplifier - 1.25V GND 7.3 Feature Description 7.3.1 OutputOvervoltageProtection The overvoltage comparator compares the FB pin voltage to a voltage that is 10% higher than the internal reference Vref. Once the FB pin voltage goes 10% above the internal reference, the internal NMOS control switchisturnedoff,whichallowstheoutputvoltagetodecreasetowardregulation. 7.3.2 UndervoltageLockout Undervoltage lockout (UVLO) prevents the LM2736 device from operating until the input voltage exceeds 2.74 V (typ). The UVLO threshold has approximately 440mV of hysteresis, so the part will operate until V drops below 2.3 V IN (typ).HysteresispreventsthepartfromturningoffduringpowerupifV isnon-monotonic. IN 7.3.3 CurrentLimit The LM2736 device uses cycle-by-cycle current limiting to protect the output switch. During each switching cycle, a current limit comparator detects if the output switch current exceeds 1.5 A (typ), and turns off the switch until thenextswitchingcyclebegins. 7.3.4 ThermalShutdown Thermal shutdown limits total power dissipation by turning off the output switch when the IC junction temperature exceeds 165°C. After thermal shutdown occurs, the output switch doesn’t turn on until the junction temperature dropstoapproximately150°C. Copyright©2004–2014,TexasInstrumentsIncorporated SubmitDocumentationFeedback 9 ProductFolderLinks:LM2736

LM2736 SNVS316H–SEPTEMBER2004–REVISEDDECEMBER2014 www.ti.com 7.4 Device Functional Modes 7.4.1 EnablePin/ShutdownMode The LM2736 device has a shutdown mode that is controlled by the enable pin (EN). When a logic low voltage is applied to EN, the part is in shutdown mode and its quiescent current drops to typically 30 nA. Switch leakage addsanother40nAfromtheinputsupply.ThevoltageatthispinshouldneverexceedV +0.3V. IN 7.4.2 Soft-Start This function forces V to increase at a controlled rate during start up. During soft-start, the error amplifier’s OUT reference voltage ramps from 0 V to its nominal value of 1.25 V in approximately 200 µs. This forces the regulatoroutputtorampupinamorelinearandcontrolledfashion,whichhelpsreduceinrushcurrent. 10 SubmitDocumentationFeedback Copyright©2004–2014,TexasInstrumentsIncorporated ProductFolderLinks:LM2736

LM2736 www.ti.com SNVS316H–SEPTEMBER2004–REVISEDDECEMBER2014 8 Application and Implementation NOTE Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validateandtesttheirdesignimplementationtoconfirmsystemfunctionality. 8.1 Application Information 8.1.1 BoostFunction Capacitor C and diode D2 in Figure 12 are used to generate a voltage V . V - V is the gate BOOST BOOST BOOST SW drive voltage to the internal NMOS control switch. To properly drive the internal NMOS switch during its on-time, V needs to be at least 1.6 V greater than V . Although the LM2736 device will operate with this minimum BOOST SW voltage, it may not have sufficient gate drive to supply large values of output current. Therefore, it is recommended that V be greater than 2.5 V above V for best efficiency. V – V should not exceed BOOST SW BOOST SW themaximumoperatinglimitof5.5V. 5.5V> V –V > 2.5Vforbestperformance. BOOST SW VBOOST D2 VIN VIN BOOST CIN CBOOST L SW VOUT GND D1 COUT Figure12. V ChargesC OUT BOOST When the LM2736 device starts up, internal circuitry from the BOOST pin supplies a maximum of 20 mA to C . This current charges C to a voltage sufficient to turn the switch on. The BOOST pin will continue to BOOST BOOST sourcecurrenttoC untilthevoltageatthefeedbackpinisgreaterthan1.18V. BOOST TherearevariousmethodstoderiveV : BOOST 1. Fromtheinputvoltage(V ) IN 2. Fromtheoutputvoltage(V ) OUT 3. Fromanexternaldistributedvoltagerail(V ) EXT 4. Fromashuntorserieszenerdiode In the Functional Block Diagram, capacitor C and diode D2 supply the gate-drive current for the NMOS BOOST switch. Capacitor C is charged via diode D2 by V . During a normal switching cycle, when the internal BOOST IN NMOS control switch is off (T ) (refer to Figure 11), V equals V minus the forward voltage of D2 (V ), OFF BOOST IN FD2 during which the current in the inductor (L) forward biases the Schottky diode D1 (V ). Therefore the voltage FD1 storedacrossC is BOOST V -V =V -V +V (1) BOOST SW IN FD2 FD1 WhentheNMOSswitchturnson(T ),theswitchpinrisesto ON V =V –(R xI ), (2) SW IN DSON L forcingV torisethusreversebiasingD2.ThevoltageatV isthen BOOST BOOST V =2V –(R xI )–V +V (3) BOOST IN DSON L FD2 FD1 whichisapproximately 2V -0.4V (4) IN formanyapplications.Thusthegate-drivevoltageoftheNMOSswitchisapproximately Copyright©2004–2014,TexasInstrumentsIncorporated SubmitDocumentationFeedback 11 ProductFolderLinks:LM2736

LM2736 SNVS316H–SEPTEMBER2004–REVISEDDECEMBER2014 www.ti.com Application Information (continued) V -0.2V (5) IN An alternate method for charging C is to connect D2 to the output as shown in Figure 12. The output BOOST voltage should be between 2.5 V and 5.5 V, so that proper gate voltage will be applied to the internal switch. In thiscircuit,C providesagatedrivevoltagethatisslightlylessthanV . BOOST OUT In applications where both V and V are greater than 5.5 V, or less than 3 V, C cannot be charged IN OUT BOOST directly from these voltages. If V and V are greater than 5.5 V, C can be charged from V or V IN OUT BOOST IN OUT minus a zener voltage by placing a zener diode D3 in series with D2, as shown in Figure 13. When using a series zener diode from the input, ensure that the regulation of the input supply doesn’t create a voltage that falls outsidetherecommendedV voltage. BOOST (V –V )<5.5V (6) INMAX D3 (V –V )>1.6V (7) INMIN D3 D2 D3 VIN VIN BOOST VBOOST CIN CBOOST L SW VOUT GND D1 COUT Figure13. ZenerReducesBoostVoltagefromV IN An alternative method is to place the zener diode D3 in a shunt configuration as shown in Figure 14. A small 350 mW to 500 mW 5.1 V zener in a SOT or SOD package can be used for this purpose. A small ceramic capacitor such as a 6.3 V, 0.1 µF capacitor (C4) should be placed in parallel with the zener diode. When the internal NMOS switch turns on, a pulse of current is drawn to charge the internal NMOS gate capacitance. The 0.1 µF parallelshuntcapacitorensuresthattheV voltageismaintainedduringthistime. BOOST Resistor R3 should be chosen to provide enough RMS current to the zener diode (D3) and to the BOOST pin. A recommended choice for the zener current (I ) is 1 mA. The current I into the BOOST pin supplies the ZENER BOOST gate current of the NMOS control switch and varies typically according to the following formula for the X - version: I =0.49x(D+0.54)x(V –V )mA (8) BOOST ZENER D2 I canbecalculatedfortheYversionusingthefollowing: BOOST I =0.20x(D+0.54)x(V -V )µA (9) BOOST ZENER D2 whereDisthedutycycle,V andV areinvolts,andI isinmilliamps.V isthevoltageappliedto ZENER D2 BOOST ZENER the anode of the boost diode (D2), and V is the average forward voltage across D2. Note that this formula for D2 I gives typical current. For the worst case I , increase the current by 40%. In that case, the worst case BOOST BOOST boostcurrentwillbe I =1.4xI (10) BOOST-MAX BOOST R3willthenbegivenby R3=(V -V )/(1.4xI +I ) (11) IN ZENER BOOST ZENER For example, using the X-version let V = 10 V, V = 5 V, V = 0.7 V, I = 1 mA, and duty cycle D = IN ZENER D2 ZENER 50%.Then I =0.49x(0.5+0.54)x(5-0.7)mA=2.19mA (12) BOOST R3=(10V-5V)/(1.4x2.19mA+1mA)=1.23kΩ (13) 12 SubmitDocumentationFeedback Copyright©2004–2014,TexasInstrumentsIncorporated ProductFolderLinks:LM2736

LM2736 www.ti.com SNVS316H–SEPTEMBER2004–REVISEDDECEMBER2014 Application Information (continued) VZ C4 D3 D2 R3 VIN VIN BOOST VBOOST CIN CBOOST L SW VOUT GND D1 COUT Figure14. BoostVoltageSuppliedfromtheShuntZeneronV IN 8.2 Typical Applications 8.2.1 LM2736X(1.6MHz)V DerivedfromV 5Vto1.5V/750mA BOOST IN D2 VIN VIN BOOST C3 L1 C1 R3 SW VOUT ON D1 C2 EN OFF R1 FB GND R2 Figure15. LM2736X(1.6MHz)V DerivedfromV 5Vto1.5V/750mA BOOST IN 8.2.1.1 DesignRequirements Derive charge for V from the input supply (V ). V – V should not exceed the maximum operating BOOST IN BOOST SW limitof5.5V. 8.2.1.2 DetailedDesignProcedures Table1.BillofMaterialsforFigure15 PARTID PARTVALUE PARTNUMBER MANUFACTURER U1 750mABuckRegulator LM2736X TI C1,InputCap 10-µF,6.3V,X5R C3216X5ROJ106M TDK C2,OutputCap 10-µF,6.3V,X5R C3216X5ROJ106M TDK C3,BoostCap 0.01-uF,16V,X7R C1005X7R1C103K TDK D1,CatchDiode 0.3V Schottky1A,10VR MBRM110L ONSemi F D2,BoostDiode 1V @50mADiode 1N4148W Diodes,Inc. F Copyright©2004–2014,TexasInstrumentsIncorporated SubmitDocumentationFeedback 13 ProductFolderLinks:LM2736

LM2736 SNVS316H–SEPTEMBER2004–REVISEDDECEMBER2014 www.ti.com Typical Applications (continued) Table1.BillofMaterialsforFigure15 (continued) PARTID PARTVALUE PARTNUMBER MANUFACTURER L1 4.7-µH,1.7A, VLCF4020T-4R7N1R2 TDK R1 2kΩ,1% CRCW06032001F Vishay R2 10kΩ,1% CRCW06031002F Vishay R3 100kΩ,1% CRCW06031003F Vishay 8.2.1.2.1 InductorSelection The Duty Cycle (D) can be approximated quickly using the ratio of output voltage (V ) to input voltage (V ) as O IN showninEquation14: V O D = V IN (14) The catch diode (D1) forward voltage drop and the voltage drop across the internal NMOS must be included to calculateamoreaccuratedutycycle.UseEquation15toCalculateD. V + V O D D = V + V - V IN D SW (15) V canbeapproximatedby: SW V =I xR (16) SW O DS(ON) The diode forward drop (V ) can range from 0.3 V to 0.7 V depending on the quality of the diode. The lower V D D is,thehighertheoperatingefficiencyoftheconverter. The inductor value determines the output ripple current. Lower inductor values decrease the size of the inductor, but increase the output ripple current. An increase in the inductor value will decrease the output ripple current. The ratio of ripple current (Δi ) to output current (I ) is optimized when it is set between 0.3 and 0.4 at 750 mA. L O Theratiorisdefinedin. 'i L r = l O (17) One must also ensure that the minimum current limit (1.0 A) is not exceeded, so the peak current in the inductor mustbecalculated.UseEquation18tocalculatethepeakcurrent(I )intheinductor. LPK I =I +ΔI /2 (18) LPK O L If r = 0.7 at an output of 750 mA, the peak current in the inductor will be 1.0125 A. The minimum ensured current limit over all operating conditions is 1.0 A. One can either reduce r to 0.6 resulting in a 975 mA peak current, or make the engineering judgement that 12.5 mA over will be safe enough with a 1.5 A typical current limit and 6 sigmalimits.Whenthedesignedmaximumoutputcurrentisreduced,theratiorcanbeincreased.Atacurrentof 0.1 A, r can be made as high as 0.9. The ripple ratio can be increased at lighter loads because the net ripple is actually quite low, and if r remains constant the inductor value can be made quite large. Equation 19 is empiricallydevelopedforthemaximumrippleratioatanycurrentbelow2A. r=0.387xI -0.3667 (19) OUT Notethatthisisjustaguideline. The LM2736 device operates at frequencies allowing the use of ceramic output capacitors without compromising transient response. Ceramic capacitors allow higher inductor ripple without significantly increasing output ripple. SeetheOutputCapacitorsectionformoredetailsoncalculatingoutputvoltageripple. Nowthattheripplecurrentorrippleratioisdetermined,theinductanceiscalculatedusingEquation20 V + V O D L = x (1-D) I x r x f O S (20) 14 SubmitDocumentationFeedback Copyright©2004–2014,TexasInstrumentsIncorporated ProductFolderLinks:LM2736

LM2736 www.ti.com SNVS316H–SEPTEMBER2004–REVISEDDECEMBER2014 where f is the switching frequency and I is the output current. When selecting an inductor, make sure that it is s O capable of supporting the peak output current without saturating. Inductor saturation will result in a sudden reduction in inductance and prevent the regulator from operating correctly. Because of the speed of the internal currentlimit,thepeakcurrentoftheinductorneedonlybespecifiedfortherequiredmaximumoutputcurrent.For example,ifthedesignedmaximumoutputcurrentis0.5Aandthepeakcurrentis0.7A,thentheinductorshould be specified with a saturation current limit of >0.7 A. There is no need to specify the saturation or peak current of theinductoratthe1.5Atypicalswitchcurrentlimit.Thedifferenceininductorsizeisafactorof5.Becauseofthe operating frequency of the LM2736, ferrite based inductors are preferred to minimize core losses. This presents little restriction since the variety of ferrite based inductors is huge. Lastly, inductors with lower series resistance (DCR)willprovidebetteroperatingefficiency.ForrecommendedinductorsseeExampleCircuits. 8.2.1.2.2 InputCapacitor An input capacitor is necessary to ensure that V does not drop excessively during switching transients. The IN primary specifications of the input capacitor are capacitance, voltage, RMS current rating, and ESL (Equivalent Series Inductance). The recommended input capacitance is 10-µF, although 4.7-µF works well for input voltages below 6 V. The input voltage rating is specifically stated by the capacitor manufacturer. Make sure to check any recommended deratings and also verify if there is any significant change in capacitance at the operating input voltage and the operating temperature. The input capacitor maximum RMS input current rating (I ) must be RMS-IN greaterthan: r2 IRMS-IN = IO x D x 1-D +12 (21) It can be shown from the above equation that maximum RMS capacitor current occurs when D = 0.5. Always calculate the RMS at the point where the duty cycle, D, is closest to 0.5. The ESL of an input capacitor is usually determined by the effective cross sectional area of the current path. A large leaded capacitor will have high ESL and a 0805 ceramic chip capacitor will have very low ESL. At the operating frequencies of the LM2736, certain capacitors may have an ESL so large that the resulting impedance (2πfL) will be higher than that required to provide stable operation. As a result, surface mount capacitors are strongly recommended. Sanyo POSCAP, Tantalum or Niobium, Panasonic SP or Cornell Dubilier ESR, and multilayer ceramic capacitors (MLCC) are all good choices for both input and output capacitors and have very low ESL. For MLCCs it is recommended to use X7R or X5R dielectrics. Consult capacitor manufacturer datasheet to see how rated capacitance varies over operatingconditions. 8.2.1.2.3 OutputCapacitor The output capacitor is selected based upon the desired output ripple and transient response. The initial current ofaloadtransientisprovidedmainlybytheoutputcapacitor.Theoutputrippleoftheconverteris: 1 'V = 'i x (R + ) O L ESR 8 x f x C S O (22) When using MLCCs, the ESR is typically so low that the capacitive ripple may dominate. When this occurs, the output ripple will be approximately sinusoidal and 90° phase shifted from the switching action. Given the availabilityandqualityofMLCCsandtheexpectedoutputvoltageofdesignsusingtheLM2736,thereisreallyno need to review any other capacitor technologies. Another benefit of ceramic capacitors is their ability to bypass high frequency noise. A certain amount of switching edge noise will couple through parasitic capacitances in the inductor to the output. A ceramic capacitor will bypass this noise while a tantalum will not. Since the output capacitor is one of the two external components that control the stability of the regulator control loop, most applications will require a minimum at 10-µF of output capacitance. Capacitance can be increased significantly with little detriment to the regulator stability. Like the input capacitor, recommended multilayer ceramic capacitors areX7RorX5R.Again,verifyactualcapacitanceatthedesiredoperatingvoltageandtemperature. Check the RMS current rating of the capacitor. The RMS current rating of the capacitor chosen must also meet thefollowingcondition: r I = I x RMS-OUT O 12 (23) Copyright©2004–2014,TexasInstrumentsIncorporated SubmitDocumentationFeedback 15 ProductFolderLinks:LM2736

LM2736 SNVS316H–SEPTEMBER2004–REVISEDDECEMBER2014 www.ti.com 8.2.1.2.4 CatchDiode The catch diode (D1) conducts during the switch off-time. A Schottky diode is recommended for its fast switching timesandlowforwardvoltagedrop.Thecatchdiodeshouldbechosensothatitscurrentratingisgreaterthan: I =I x(1-D) (24) D1 O The reverse breakdown rating of the diode must be at least the maximum input voltage plus appropriate margin. ToimproveefficiencychooseaSchottkydiodewithalowforwardvoltagedrop. 8.2.1.2.5 BoostDiode A standard diode such as the 1N4148 type is recommended. For V circuits derived from voltages less than BOOST 3.3 V, a small-signal Schottky diode is recommended for greater efficiency. A good choice is the BAT54 small signaldiode. 8.2.1.2.6 BoostCapacitor A ceramic 0.01-µF capacitor with a voltage rating of at least 16 V is sufficient. The X7R and X5R MLCCs provide thebestperformance. 8.2.1.2.7 OutputVoltage The output voltage is set using the following equation where R2 is connected between the FB pin and GND, and R1isconnectedbetweenV andtheFBpin.AgoodvalueforR2is10kΩ. O V O R1= - 1 x R2 V REF (25) 8.2.1.3 ApplicationCurves V =5V V =5V OUT OUT Figure16.EfficiencyvsLoadCurrent-"X" Figure17.EfficiencyvsLoadCurrent-"Y" 16 SubmitDocumentationFeedback Copyright©2004–2014,TexasInstrumentsIncorporated ProductFolderLinks:LM2736

LM2736 www.ti.com SNVS316H–SEPTEMBER2004–REVISEDDECEMBER2014 V =3.3V V =3.3V OUT OUT Figure18.EfficiencyvsLoadCurrent-"X" Figure19.EfficiencyvsLoadCurrent-"Y" V =1.5V V =1.5V OUT OUT Figure20.EfficiencyvsLoadCurrent-"X" Figure21.EfficiencyvsLoadCurrent-"Y" Copyright©2004–2014,TexasInstrumentsIncorporated SubmitDocumentationFeedback 17 ProductFolderLinks:LM2736

LM2736 SNVS316H–SEPTEMBER2004–REVISEDDECEMBER2014 www.ti.com 8.2.2 LM2736X(1.6MHz)V DerivedfromV 12Vto3.3V/750mA BOOST OUT D2 VIN VIN BOOST C3 L1 C1 R3 SW VOUT ON D1 C2 EN OFF R1 FB GND R2 Figure22. LM2736X(1.6MHz)V DerivedfromV 12Vto3.3V/750mA BOOST OUT 8.2.2.1 DesignRequirements DerivechargeforV fromtheoutputvoltage,(V ).Theoutputvoltageshouldbebetween2.5Vand5.5V. BOOST OUT 8.2.2.2 DetailedDesignProcedures Table2.BillofMaterialsforFigure22 PARTID PARTVALUE PARTNUMBER MANUFACTURER U1 750mABuckRegulator LM2736X TI C1,InputCap 10µF,25V,X7R C3225X7R1E106M TDK C2,OutputCap 22µF,6.3V,X5R C3216X5ROJ226M TDK C3,BoostCap 0.01µF,16V,X7R C1005X7R1C103K TDK D1,CatchDiode 0.34V Schottky1A,30VR SS1P3L Vishay F D2,BoostDiode 30V,200mASchottky BAT54 DiodesInc. L1 4.7µH,1.7A, VLCF4020T-4R7N1R2 TDK R1 16.5kΩ,1% CRCW06031652F Vishay R2 10.0kΩ,1% CRCW06031002F Vishay R3 100kΩ,1% CRCW06031003F Vishay PleaserefertoDetailedDesignProcedures. 8.2.2.3 ApplicationCurves PleaserefertoApplicationCurves 18 SubmitDocumentationFeedback Copyright©2004–2014,TexasInstrumentsIncorporated ProductFolderLinks:LM2736

LM2736 www.ti.com SNVS316H–SEPTEMBER2004–REVISEDDECEMBER2014 8.2.3 LM2736X(1.6MHz)V DerivedfromV 18Vto1.5V/750mA BOOST SHUNT C4 D3 R4 D2 VIN VIN BOOST C3 L1 C1 R3 SW VOUT ON D1 C2 EN OFF R1 FB GND R2 Figure23. LM2736X(1.6MHz)V DerivedfromV 18Vto1.5V/750mA BOOST SHUNT 8.2.3.1 DesignRequirements An alternative method when V is greater than 5.5V is to place the zener diode D3 in a shunt configuration. A IN small 350 mW to 500 mW 5.1 V zener in a SOT or SOD package can be used for this purpose. A small ceramic capacitor such as a 6.3 V, 0.1 µF capacitor (C4) should be placed in parallel with the zener diode. When the internal NMOS switch turns on, a pulse of current is drawn to charge the internal NMOS gate capacitance. The 0.1 µFparallelshuntcapacitorensuresthattheV voltageismaintainedduringthistime BOOST 8.2.3.2 DetailedDesignProcedure Table3.BillofMaterialsforFigure23 PARTID PARTVALUE PARTNUMBER MANUFACTURER U1 750mABuckRegulator LM2736X TI C1,InputCap 10µF,25V,X7R C3225X7R1E106M TDK C2,OutputCap 22µF,6.3V,X5R C3216X5ROJ226M TDK C3,BoostCap 0.01µF,16V,X7R C1005X7R1C103K TDK C4,ShuntCap 0.1µF,6.3V,X5R C1005X5R0J104K TDK D1,CatchDiode 0.4V Schottky1A,30VR SS1P3L Vishay F D2,BoostDiode 1V @50mADiode 1N4148W Diodes,Inc. F D3,ZenerDiode 5.1V250MwSOT BZX84C5V1 Vishay L1 6.8µH,1.6A, SLF7032T-6R8M1R6 TDK R1 2kΩ,1% CRCW06032001F Vishay R2 10kΩ,1% CRCW06031002F Vishay R3 100kΩ,1% CRCW06031003F Vishay R4 4.12kΩ,1% CRCW06034121F Vishay PleaserefertoDetailedDesignProcedures. 8.2.3.3 ApplicationCurves PleaserefertoApplicationCurves. Copyright©2004–2014,TexasInstrumentsIncorporated SubmitDocumentationFeedback 19 ProductFolderLinks:LM2736

LM2736 SNVS316H–SEPTEMBER2004–REVISEDDECEMBER2014 www.ti.com 8.2.4 LM2736X(1.6MHz)V DerivedfromSeriesZenerDiode(V )15Vto1.5V/750mA BOOST IN D3 D2 VIN VIN BOOST C3 C1 L1 R3 SW VOUT ON D1 C2 EN OFF R1 FB GND R2 Figure24. LM2736X(1.6MHz)V DerivedfromSeriesZenerDiode(V )15Vto1.5V/750mA BOOST IN 8.2.4.1 DesignRequirements In applications where both V and V are greater than 5.5 V, or less than 3 V, C cannot be charged IN OUT BOOST directly from these voltages. If V is greater than 5.5 V, C can be charged from V minus a zener voltage IN BOOST IN by placing a zener diode D3 in series with D2. When using a series zener diode from the input, ensure that the regulationoftheinputsupplydoesn’tcreateavoltagethatfallsoutsidetherecommendedV voltage. BOOST (V –V )<5.5V (26) INMAX D3 (V –V )>1.6V (27) INMIN D3 8.2.4.2 DetailedDesignProcedure Table4.BillofMaterialsforFigure24 PARTID PARTVALUE PARTNUMBER MANUFACTURER U1 750mABuckRegulator LM2736X TI C1,InputCap 10-µF,25V,X7R C3225X7R1E106M TDK C2,OutputCap 22-µF,6.3V,X5R C3216X5ROJ226M TDK C3,BoostCap 0.01-µF,16V,X7R C1005X7R1C103K TDK D1,CatchDiode 0.4V Schottky1A,30VR SS1P3L Vishay F D2,BoostDiode 1V @50mADiode 1N4148W Diodes,Inc. F D3,ZenerDiode 11V350MwSOT BZX84C11T Diodes,Inc. L1 6.8µH,1.6A, SLF7032T-6R8M1R6 TDK R1 2kΩ,1% CRCW06032001F Vishay R2 10kΩ,1% CRCW06031002F Vishay R3 100kΩ,1% CRCW06031003F Vishay PleaserefertoDetailedDesignProcedures. 8.2.4.3 ApplicationCurves PleaserefertoApplicationCurves 20 SubmitDocumentationFeedback Copyright©2004–2014,TexasInstrumentsIncorporated ProductFolderLinks:LM2736

LM2736 www.ti.com SNVS316H–SEPTEMBER2004–REVISEDDECEMBER2014 8.2.5 LM2736X(1.6MHz)V DerivedfromSeriesZenerDiode(V )15Vto9V/750mA BOOST OUT D2 D3 VIN VIN BOOST C3 L1 C1 R3 SW VOUT ON D1 C2 EN OFF R1 FB GND R2 Figure25. 8.2.5.1 DesignRequirements In applications where both V and V are greater than 5.5 V, or less than 3 V, C cannot be charged IN OUT BOOST directly from these voltages. If V and V are greater than 5.5 V, C can be charged from V minus a IN OUT BOOST OUT zenervoltagebyplacingazenerdiodeD3inserieswithD2. 8.2.5.2 DetailedDesignProcedure Table5.BillofMaterialsforFigure25 PARTID PARTVALUE PARTNUMBER MANUFACTURER U1 750mABuckRegulator LM2736X TI C1,InputCap 10µF,25V,X7R C3225X7R1E106M TDK C2,OutputCap 22µF,16V,X5R C3216X5R1C226M TDK C3,BoostCap 0.01µF,16V,X7R C1005X7R1C103K TDK D1,CatchDiode 0.4V Schottky1A,30VR SS1P3L Vishay F D2,BoostDiode 1V @50mADiode 1N4148W Diodes,Inc. F D3,ZenerDiode 4.3V350mwSOT BZX84C4V3 Diodes,Inc. L1 6.8µH,1.6A, SLF7032T-6R8M1R6 TDK R1 61.9kΩ,1% CRCW06036192F Vishay R2 10kΩ,1% CRCW06031002F Vishay R3 100kΩ,1% CRCW06031003F Vishay PleaserefertoDetailedDesignProcedures. 8.2.5.3 ApplicationCurves PleaserefertoApplicationCurves Copyright©2004–2014,TexasInstrumentsIncorporated SubmitDocumentationFeedback 21 ProductFolderLinks:LM2736

LM2736 SNVS316H–SEPTEMBER2004–REVISEDDECEMBER2014 www.ti.com 8.2.6 LM2736Y(550kHz)V DerivedfromV 5Vto1.5V/750mA BOOST IN D2 VIN VIN BOOST C3 L1 C1 R3 SW VOUT ON D1 C2 EN OFF R1 FB GND R2 Figure26. LM2736Y(550kHz)V DerivedfromV 5Vto1.5V/750mA BOOST IN 8.2.6.1 DesignRequirements Derive charge for V from the input voltage, (V ). V should be greater than 2.5 V above V for best BOOST IN BOOST SW efficiency.V –V shouldnotexceedthemaximumoperatinglimitof5.5V. BOOST SW 8.2.6.2 DetailedDesignProcedure Table6.BillofMaterialsforFigure26 PARTID PARTVALUE PARTNUMBER MANUFACTURER U1 750mABuckRegulator LM2736Y TI C1,InputCap 10µF,6.3V,X5R C3216X5ROJ106M TDK C2,OutputCap 22µF,6.3V,X5R C3216X5ROJ226M TDK C3,BoostCap 0.01µF,16V,X7R C1005X7R1C103K TDK D1,CatchDiode 0.3V Schottky1A,10VR MBRM110L ONSemi F D2,BoostDiode 1V @50mADiode 1N4148W Diodes,Inc. F L1 10µH,1.6A, SLF7032T-100M1R4 TDK R1 2kΩ,1% CRCW06032001F Vishay R2 10kΩ,1% CRCW06031002F Vishay R3 100kΩ,1% CRCW06031003F Vishay PleaserefertoDetailedDesignProcedures. 8.2.6.3 ApplicationCurves PleaserefertoApplicationCurves. 22 SubmitDocumentationFeedback Copyright©2004–2014,TexasInstrumentsIncorporated ProductFolderLinks:LM2736

LM2736 www.ti.com SNVS316H–SEPTEMBER2004–REVISEDDECEMBER2014 8.2.7 LM2736Y(550kHz)V DerivedfromV 12Vto3.3V/750mA BOOST OUT D2 VIN VIN BOOST C3 L1 C1 R3 SW VOUT ON D1 C2 EN OFF R1 FB GND R2 Figure27. LM2736Y(550kHz)V DerivedfromV 12Vto3.3V/750mA BOOST OUT 8.2.7.1 DesignRequirements DerivechargeforV fromtheoutputvoltage,(V ).Theoutputvoltageshouldbebetween2.5Vand5.5V. BOOST OUT 8.2.7.2 DetailedDesignProcedure Table7.BillofMaterialsforFigure27 PARTID PARTVALUE PARTNUMBER MANUFACTURER U1 750mABuckRegulator LM2736Y TI C1,InputCap 10µF,25V,X7R C3225X7R1E106M TDK C2,OutputCap 22µF,6.3V,X5R C3216X5ROJ226M TDK C3,BoostCap 0.01µF,16V,X7R C1005X7R1C103K TDK D1,CatchDiode 0.34V Schottky1A,30VR SS1P3L Vishay F D2,BoostDiode 30V,200mASchottky BAT54 DiodesInc. L1 10µH,1.6A, SLF7032T-100M1R4 TDK R1 16.5kΩ,1% CRCW06031652F Vishay R2 10.0kΩ,1% CRCW06031002F Vishay R3 100kΩ,1% CRCW06031003F Vishay PleaserefertoDetailedDesignProcedures. 8.2.7.3 ApplicationCurves PleaserefertoApplicationCurves. Copyright©2004–2014,TexasInstrumentsIncorporated SubmitDocumentationFeedback 23 ProductFolderLinks:LM2736

LM2736 SNVS316H–SEPTEMBER2004–REVISEDDECEMBER2014 www.ti.com 8.2.8 LM2736Y(550kHz)V DerivedfromV 18Vto1.5V/750mA BOOST SHUNT C4 D3 R4 D2 VIN VIN BOOST C3 L1 C1 R3 SW VOUT ON D1 C2 EN OFF R1 FB GND R2 Figure28. LM2736Y(550kHz)V DerivedfromV 18Vto1.5V/750mA BOOST SHUNT 8.2.8.1 DesignRequirements An alternative method when V is greater than 5.5V is to place the zener diode D3 in a shunt configuration. A IN small 350 mW to 500 mW 5.1 V zener in a SOT or SOD package can be used for this purpose. A small ceramic capacitor such as a 6.3 V, 0.1 µF capacitor (C4) should be placed in parallel with the zener diode. When the internal NMOS switch turns on, a pulse of current is drawn to charge the internal NMOS gate capacitance. The 0.1 µFparallelshuntcapacitorensuresthattheV voltageismaintainedduringthistime. BOOST 8.2.8.2 DetailedDesignProcedure Table8.BillofMaterialsforFigure28 PARTID PARTVALUE PARTNUMBER MANUFACTURER U1 750mABuckRegulator LM2736Y TI C1,InputCap 10µF,25V,X7R C3225X7R1E106M TDK C2,OutputCap 22µF,6.3V,X5R C3216X5ROJ226M TDK C3,BoostCap 0.01µF,16V,X7R C1005X7R1C103K TDK C4,ShuntCap 0.1µF,6.3V,X5R C1005X5R0J104K TDK D1,CatchDiode 0.4V Schottky1A,30VR SS1P3L Vishay F D2,BoostDiode 1V @50mADiode 1N4148W Diodes,Inc. F D3,ZenerDiode 5.1V250MwSOT BZX84C5V1 Vishay L1 15µH,1.5A SLF7045T-150M1R5 TDK R1 2kΩ,1% CRCW06032001F Vishay R2 10kΩ,1% CRCW06031002F Vishay R3 100kΩ,1% CRCW06031003F Vishay R4 4.12kΩ,1% CRCW06034121F Vishay PleaserefertoDetailedDesignProcedures. 8.2.8.3 ApplicationCurves PleaserefertoApplicationCurves. 24 SubmitDocumentationFeedback Copyright©2004–2014,TexasInstrumentsIncorporated ProductFolderLinks:LM2736

LM2736 www.ti.com SNVS316H–SEPTEMBER2004–REVISEDDECEMBER2014 8.2.9 LM2736Y(550kHz)V DerivedfromSeriesZenerDiode(V )15Vto1.5V/750mA BOOST IN D3 D2 VIN VIN BOOST C3 C1 L1 R3 SW VOUT ON D1 C2 EN OFF R1 FB GND R2 Figure29. M2736Y(550kHz)V DerivedfromSeriesZenerDiode(V )15Vto1.5V/750mA BOOST IN 8.2.9.1 DesignRequirements In applications where both V and V are greater than 5.5 V, or less than 3 V, C cannot be charged IN OUT BOOST directly from these voltages. If V is greater than 5.5 V, C can be charged from V minus a zener voltage IN BOOST IN by placing a zener diode D3 in series with D2. When using a series zener diode from the input, ensure that the regulationoftheinputsupplydoesn’tcreateavoltagethatfallsoutsidetherecommendedV voltage. BOOST (V –V )<5.5V (28) INMAX D3 (V –V )>1.6V (29) INMIN D3 8.2.9.2 DetailedDesignProcedure Table9.BillofMaterialsforFigure29 PARTID PARTVALUE PARTNUMBER MANUFACTURER U1 750mABuckRegulator LM2736Y TI C1,InputCap 10µF,25V,X7R C3225X7R1E106M TDK C2,OutputCap 22µF,6.3V,X5R C3216X5ROJ226M TDK C3,BoostCap 0.01µF,16V,X7R C1005X7R1C103K TDK D1,CatchDiode 0.4V Schottky1A,30VR SS1P3L Vishay F D2,BoostDiode 1V @50mADiode 1N4148W Diodes,Inc. F D3,ZenerDiode 11V350MwSOT BZX84C11T Diodes,Inc. L1 15µH,1.5A, SLF7045T-150M1R5 TDK R1 2kΩ,1% CRCW06032001F Vishay R2 10kΩ,1% CRCW06031002F Vishay R3 100kΩ,1% CRCW06031003F Vishay PleaserefertoDetailedDesignProcedures. 8.2.9.3 ApplicationCurves PleaserefertoApplicationCurves. Copyright©2004–2014,TexasInstrumentsIncorporated SubmitDocumentationFeedback 25 ProductFolderLinks:LM2736

LM2736 SNVS316H–SEPTEMBER2004–REVISEDDECEMBER2014 www.ti.com 8.2.10 LM2736Y(550kHz)V DerivedfromSeriesZenerDiode(V )15Vto9V/750mA BOOST OUT D2 D3 VIN VIN BOOST C3 L1 C1 R3 SW VOUT ON D1 C2 EN OFF R1 FB GND R2 Figure30. LM2736Y(550kHz)V DerivedfromSeriesZenerDiode(V )15Vto9V/750mA BOOST OUT 8.2.10.1 DesignRequirements In applications where both V and V are greater than 5.5 V, or less than 3 V, C cannot be charged IN OUT BOOST directly from these voltages. If V and V are greater than 5.5 V, C can be charged from V minus a IN OUT BOOST OUT zenervoltagebyplacingazenerdiodeD3inserieswithD2. 8.2.10.2 DetailedDesignProcedure Table10.BillofMaterialsforFigure30 PARTID PARTVALUE PARTNUMBER MANUFACTURER U1 750mABuckRegulator LM2736Y TI C1,InputCap 10-µF,25V,X7R C3225X7R1E106M TDK C2,OutputCap 22-µF,16V,X5R C3216X5R1C226M TDK C3,BoostCap 0.01-µF,16V,X7R C1005X7R1C103K TDK D1,CatchDiode 0.4V Schottky1A,30VR SS1P3L Vishay F D2,BoostDiode 1V @50mADiode 1N4148W Diodes,Inc. F D3,ZenerDiode 4.3V350mwSOT BZX84C4V3 Diodes,Inc. L1 22µH,1.4A, SLF7045T-220M1R3-1PF TDK R1 61.9kΩ,1% CRCW06036192F Vishay R2 10kΩ,1% CRCW06031002F Vishay R3 100kΩ,1% CRCW06031003F Vishay PleaserefertoDetailedDesignProcedures. 8.2.10.3 ApplicationCurves PleaserefertoApplicationCurves. 26 SubmitDocumentationFeedback Copyright©2004–2014,TexasInstrumentsIncorporated ProductFolderLinks:LM2736

LM2736 www.ti.com SNVS316H–SEPTEMBER2004–REVISEDDECEMBER2014 9 Power Supply Recommendations Input voltage is rated as 3 V to 18 V however care should be taken in certain circuit configurations eg. V BOOST derived from V where the requirement that V - V < 5.5 V should be observed. Also for best efficiency IN BOOST SW V shouldbeatleast2.5VaboveV . BOOST SW ThevoltageontheEnablepinshouldnotexceedV bymorethan0.3V. IN 10 Layout 10.1 Layout Guidelines When planning layout there are a few things to consider when trying to achieve a clean, regulated output. The mostimportantconsiderationwhencompletingthelayoutistheclosecouplingoftheGNDconnectionsoftheC IN capacitor and the catch diode D1. These ground ends should be close to one another and be connected to the GND plane with at least two through-holes. Place these components as close to the IC as possible. Next in importance is the location of the GND connection of the C capacitor, which should be near the GND OUT connectionsofC andD1. IN There should be a continuous ground plane on the bottom layer of a two-layer board except under the switching nodeisland. TheFBpinisahighimpedancenodeandcareshouldbetakentomaketheFBtraceshorttoavoidnoisepickup and inaccurate regulation. The feedback resistors should be placed as close as possible to the IC, with the GND of R2 placed as close as possible to the GND of the IC. The V trace to R1 should be routed away from the OUT inductorandanyothertracesthatareswitching. High AC currents flow through the V , SW and V traces, so they should be as short and wide as possible. IN OUT However, making the traces wide increases radiated noise, so the designer must make this trade-off. Radiated noisecanbedecreasedbychoosingashieldedinductor. The remaining components should also be placed as close as possible to the IC. Please see Application Note AN-1229 SNVA054 for further considerations and the LM2736 device demo board as an example of a four-layer layout. Copyright©2004–2014,TexasInstrumentsIncorporated SubmitDocumentationFeedback 27 ProductFolderLinks:LM2736

LM2736 SNVS316H–SEPTEMBER2004–REVISEDDECEMBER2014 www.ti.com 10.2 Layout Example Figure31. TopLayer D2 VIN VIN BOOST C3 C1 L1 R5 SW VOUT D1 C2 R1 VEN EN FB GND R2 Figure32. LayoutSchematic 28 SubmitDocumentationFeedback Copyright©2004–2014,TexasInstrumentsIncorporated ProductFolderLinks:LM2736

LM2736 www.ti.com SNVS316H–SEPTEMBER2004–REVISEDDECEMBER2014 11 Device and Documentation Support 11.1 Device Support 11.1.1 Third-PartyProductsDisclaimer TI'S PUBLICATION OF INFORMATION REGARDING THIRD-PARTY PRODUCTS OR SERVICES DOES NOT CONSTITUTE AN ENDORSEMENT REGARDING THE SUITABILITY OF SUCH PRODUCTS OR SERVICES OR A WARRANTY, REPRESENTATION OR ENDORSEMENT OF SUCH PRODUCTS OR SERVICES, EITHER ALONEORINCOMBINATIONWITHANYTIPRODUCTORSERVICE. 11.2 Documentation Support 11.2.1 RelatedDocumentation Forrelateddocumentationseethefollowing: • AN-1229SIMPLESWITCHER®PCBLayoutGuidelines SNVA054 11.3 Trademarks WEBENCH,SIMPLESWITCHERareregisteredtrademarksofTexasInstruments. Allothertrademarksarethepropertyoftheirrespectiveowners. 11.4 Electrostatic Discharge Caution Thesedeviceshavelimitedbuilt-inESDprotection.Theleadsshouldbeshortedtogetherorthedeviceplacedinconductivefoam duringstorageorhandlingtopreventelectrostaticdamagetotheMOSgates. 11.5 Glossary SLYZ022—TIGlossary. Thisglossarylistsandexplainsterms,acronyms,anddefinitions. 12 Mechanical, Packaging, and Orderable Information The following pages include mechanical, packaging, and orderable information. This information is the most current data available for the designated devices. This data is subject to change without notice and revision of thisdocument.Forbrowser-basedversionsofthisdatasheet,refertotheleft-handnavigation. Copyright©2004–2014,TexasInstrumentsIncorporated SubmitDocumentationFeedback 29 ProductFolderLinks:LM2736

PACKAGE OPTION ADDENDUM www.ti.com 22-Dec-2014 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) LM2736XMK NRND SOT DDC 6 1000 TBD Call TI Call TI -40 to 125 SHAB LM2736XMK/NOPB ACTIVE SOT DDC 6 1000 Green (RoHS CU SN Level-1-260C-UNLIM -40 to 125 SHAB & no Sb/Br) LM2736XMKX/NOPB ACTIVE SOT DDC 6 3000 Green (RoHS CU SN Level-1-260C-UNLIM -40 to 125 SHAB & no Sb/Br) LM2736YMK NRND SOT DDC 6 1000 TBD Call TI Call TI -40 to 125 SHBB LM2736YMK/NOPB ACTIVE SOT DDC 6 1000 Green (RoHS CU SN Level-1-260C-UNLIM -40 to 125 SHBB & no Sb/Br) LM2736YMKX/NOPB ACTIVE SOT DDC 6 3000 Green (RoHS CU SN Level-1-260C-UNLIM -40 to 125 SHBB & no Sb/Br) (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. (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. Addendum-Page 1

PACKAGE OPTION ADDENDUM www.ti.com 22-Dec-2014 (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. 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-Dec-2016 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) LM2736XMK SOT DDC 6 1000 178.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3 LM2736XMK/NOPB SOT DDC 6 1000 178.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3 LM2736XMKX/NOPB SOT DDC 6 3000 178.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3 LM2736YMK SOT DDC 6 1000 178.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3 LM2736YMK/NOPB SOT DDC 6 1000 178.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3 LM2736YMKX/NOPB SOT DDC 6 3000 178.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3 PackMaterials-Page1

PACKAGE MATERIALS INFORMATION www.ti.com 20-Dec-2016 *Alldimensionsarenominal Device PackageType PackageDrawing Pins SPQ Length(mm) Width(mm) Height(mm) LM2736XMK SOT DDC 6 1000 210.0 185.0 35.0 LM2736XMK/NOPB SOT DDC 6 1000 210.0 185.0 35.0 LM2736XMKX/NOPB SOT DDC 6 3000 210.0 185.0 35.0 LM2736YMK SOT DDC 6 1000 210.0 185.0 35.0 LM2736YMK/NOPB SOT DDC 6 1000 210.0 185.0 35.0 LM2736YMKX/NOPB SOT DDC 6 3000 210.0 185.0 35.0 PackMaterials-Page2

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