LT3959 - Wide Input Voltage Range Boost/SEPIC/Inverting ...

1 LT395913959faFor more information applicaTion FeaTuresDescripTionWide Input Voltage Range Boost/SEPIC/Inverting Converter with 6A, 40V to 24V Input , 12V Output SEPIC ConverterExcellent for Automotive 12V Post Regulator applicaTionsn wide VIN Range : ( Start-Up) to 40Vn Positive or Negative Output Voltage Programming with a Single Feedback Pinn PGOOD Output Voltage Status Reportn Internal 6A/40V Power Switchn Programmable Soft-Startn Programmable Operating Frequency (100kHz to 1 MHz) with One External Resistorn Synchronizable to an External Clockn Low Shutdown Current < 1 An INTVCC Regulator Supplied from VIN or DRIVEn Programmable Input Undervoltage Lockout with Hysteresisn Thermally Enhanced QFN (5mm 6mm)

2 And TSSOP Packagesn Automotiven Telecomn IndustrialL, LT, LT C, LT M, Linear Technology and the Linear logo are registered trademarks and ThinSOT are trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by Patents, including LT 3959 is a wide Input Range , current mode, DC/DC controller which is capable of regulating either positive or negative output voltages from a single feedback pin. It can be configured as a boost, SEPIC or inverting converter. It features an internal low side N-channel MOSFET rated for 6A at 40V and driven from an internal regulated sup-ply provided from VIN or DRIVE.

3 The fixed frequency, current-mode architecture results in stable operation over a wide Range of supply and output voltages. The operating frequency of LT3959 can be set over a 100kHz to 1 MHz Range with an external resistor, or can be synchronized to an external clock using the SYNC pin. The LT3959 features soft-start and frequency foldback functions to limit inductor current during start-up and output short-circuit. A window comparator on the FBX pin reports via the PGOOD pin, providing output Voltage status vs Output CurrentOUTPUT CURRENT (mA)0 EFFICIENCY (%)909510060010003959 TA01b852004008008075706560 VIN = TO24 VCIN22 F50V F50 VGNDDRIVEFBXSGNDINTVCCEN_UVLOPGOODSYNCTI E TO SGNDIF NOT FVOUT12V500mA AT VIN = AT VIN > 8V3959 F16V 2LT395923959faFor more information conFiguraTionabsoluTe MaxiMuM raTingsVIN.

4 40 VEN/UVLO (Note 2) ..40 VDRIVE ..40 VPGOOD ..40 VSW ..40 VINTVCC ..8 VSYNC ..8V(Note 1)VC, SS ..3 VRT .. , GNDK to SGND .. 3V to 3 VOperating Junction Temper atur e Range (Note 3) LT3959E/ LT3959I .. 40 C to 125 CStorage Temper atur e Range .. 65 C to 125 C121314 TOP VIEWUHEMA PACKAGE36-LEAD (5mm 6mm) PLASTIC QFN1516173635343332313021232425272886432 1 NCNCNCSGNDNCSWSWNCDRIVEVINEN/UVLOSGNDNCS WSWINTVCCPGOODSYNCRTSSFBXVCGNDKGNDGNDGND GNDGND2091037 SGND38SW TJMAX =125 C, JA = 42 C/W, JC = 3 C/WEXPOSED PAD (PIN 37) IS SGND, MUST BE SOLDERED TO SGND PLANEEXPOSED PAD (PIN 38)

5 IS SW, MUST BE SOLDERED TO SW PLANE12345678910111213141516171819 TOP VIEWFE PACKAGE38-LEAD PLASTIC TSSOP38373635343332313029282726252423222 120 NCNCNCVCFBXSSRTSYNCPGOODSGNDNCSWNCNCSWNC GNDKGNDGNDNCNCNCNCEN/UVLOVINDRIVEINTVCCN CSGNDNCSWNCNCSWNCGNDGNDGND39 SGND40SW TJMAX =125 C, JA = 42 C/W, JC = 3 C/WEXPOSED PAD (PIN 39) IS SGND, MUST BE SOLDERED TO SGND PLANEEXPOSED PAD (PIN 40) IS SW, MUST BE SOLDERED TO SW PLANELT395933959faFor more information characTerisTicsPARAMETERCONDITIONSMINTYP MAXUNITSVIN Operating Start-Up VoltageRT = , FBX = Shutdown IQEN/UVLO < EN/UVLO = 6 A AVIN Operating IQ350450 ADRIVE Shutdown Quiescent CurrentEN/UVLO < EN/UVLO = 2 A ADRIVE Quiescent Current (Not Switching)RT = , DRIVE = Pin Current Pin On VoltageISW = 3A100mVSW Pin Leakage CurrentSW = 40V5 AError AmplifierFBX Regulation Voltage (VFBX(REG))

6 FBX > 0V FBX < 0Vl VFBX Pin Input CurrentFBX = FBX = 1080130 10nA nATransconductance gm ( IVC/ VFBX)FBX = VFBX(REG)240 sVC Output Impedance5M FBX Line Regulation [ VFBX(REG)/( VIN VFBX(REG))] < VIN < 40V, FBX >0 < VIN < 40V, FBX < %/VVC Source CurrentFBX = 0V, VC = 13 AVC Sink CurrentFBX = , VC = FBX = , VC = 10 A AOscillatorSwitching FrequencyRT = to SGND, VFBX = RT = to SGND, VFBX = RT = to SGND, VFBX = 100 1000340kHz kHz kHzRT VoltageFBX = , Minimum Off-Time150200nsSW Minimum On-Time150200ns The l denotes the specifications which apply over the full operating temperature Range , otherwise specifications are at TA = 25 C, VIN = 12V, EN/UVLO = 12V, INTVCC =.

7 Unless otherwise inForMaTionLEAD FREE FINISHTAPE AND REELPART MARKING*PACKAGE DESCRIPTIONTEMPERATURE RANGELT3959 EUHE#PBFLT3959 EUHE#TRPBF395936-Lead (5mm 6mm) Plastic QFN 40 C to 125 CLT3959 IUHE#PBFLT3959 IUHE#TRPBF395936-Lead (5mm 6mm) Plastic QFN 40 C to 125 CLT3959 EFE#PBFLT3959 EFE#TRPBFLT3959FE38-Lead Plastic TSSOP 40 C to 125 CLT3959 IFE#PBFLT3959 IFE#TRPBFLT3959FE38-Lead Plastic TSSOP 40 C to 125 CConsult LT C Marketing for parts specified with wider operating temperature ranges . *The temperature grade is identified by a label on the shipping container. Consult LT C Marketing for information on nonstandard lead based finish more information on lead free part marking, go to: For more information on tape and reel specifications, go to.

8 More information Input Input Pull-Up CurrentSS = 0V, Current Out of Pinl 14 7 ALow Dropout Regulators (DRIVE LDO and VIN LDO)DRIVE LDO Regulation VoltageDRIVE = 6V, Not LDO Regulation VoltageDRIVE = 0V, Not LDO Current LimitINTVCC = 4V60mAVIN LDO Current LimitDRIVE = 0V, INTVCC = 3V60mADRIVE LDO Load Regulation ( VINTVCC/VINTVCC)0 < IINTVCC < 20mA, DRIVE = 6V 1 LDO Load Regulation ( VINTVCC/VINTVCC)DRIVE = 0V, 0 < IINTVCC < 20mA 1 LDO Line Regulation [ VINTVCC/(VINTVCC VIN)] < VIN < 40V, DRIVE = LDO Line Regulation [ VINTVCC/(VINTVCC VIN)]DRIVE = 0V, 5V < VIN < LDO Dropout Voltage (VDRIVE VINTVCC)DRIVE = 4V, IINTVCC = 20mAl190400mVVIN LDO Dropout Voltage (VIN VINTVCC)VIN = 3V, DRIVE = 0V, IINTVCC = 20mAl190400mVINTVCC Undervoltage Lockout Threshold Undervoltage Lockout Threshold Current in ShutdownEN/UVLO = 0V25 ALogicEN/UVLO Threshold Voltage Threshold Voltage Rising Hysteresis20mVEN/UVLO Input Low VoltageIVIN < 1 Pin Bias Current LowEN/UVLO = AEN/UVLO Pin Bias Current HighEN/UVLO = Power Good Threshold VoltageFBX > 0V, PGOOD Falling FBX < 0V, PGOOD FallingVFBX(REG) VFBX(REG)

9 + VFBX Overvoltage ThresholdFBX > 0V, PGOOD Rising FBX < 0V, PGOOD RisingVFBX(REG) + VFBX(REG) VPGOOD Output Low (VOL)IPGOOD = 250 A210300mVPGOOD Leakage CurrentPGOOD = 40V1 AINTVCC Minimum Voltage to Enable PGOOD Minimum Voltage to Enable SYNC characTerisTics The l denotes the specifications which apply over the full operating temperature Range , otherwise specifications are at TA = 25 C, VIN = 12V, EN/UVLO = 12V, INTVCC = , unless otherwise 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime.

10 Note 2: For VIN below 4V, the EN/UVLO pin must not exceed VIN for proper 3: The LT3959E is guaranteed to meet performance specifications from the 0 C to 125 C operating junction temperature. Specifications over the 40 C to 125 C operating junction temperature Range are assured by design, characterization and correlation with statistical process controls. The LT3959I is guaranteed over the full 40 C to 125 C operating junction temperature Range . Note 4: The LT3959 is tested in a feedback loop which servos VFBX to the reference voltages ( and ) with the VC pin forced to more information perForMance characTerisTicsDynamic Quiescent Currentvs Switching FrequencyRT vs Switching FrequencyNormalized Switching Frequencyvs FBX VoltageSwitching Frequencyvs TemperatureSW Current Limit vs TemperatureSW Current Limit vs Duty CycleFBX Positive Regulation Voltagevs TemperatureFBX Negative Regulation Voltagevs TemperatureQuiescent Currentvs TemperatureSWITCHING FREQUENCY (kHz)0IQ (mA)15202560010003959 G041020040080050IQ (VIN)