Micropower Synchronous Multitopology Controller …

1 LT87111 Rev AFor more information FeedbackTYPICAL APPLICATION FEATURESDESCRIPTIONM icropower Synchronous Multitopology Controller with 42V input CapabilityThe LT 8711 is a Multitopology current mode PWM control-ler that can easily be configured as a Synchronous buck, boost, SEPIC, ZETA or as a nonsynchronous buck-boost converter. Its dual gate drive voltage inputs optimize gate driver 15 A no-load quiescent current with the output voltage in regulation extends operating run time in battery powered systems. Low ripple Burst Mode operation enables high efficiency at very light loads while maintaining low output voltage ripple. The LT8711's fixed switching frequency can be set from 100kHz to 750kHz or can be synchronized to an external additional features include 100% duty cycle capability when in buck mode, a topology selection pin and adjustable soft-start. LT8711 is available in the 20-lead TSSOP and 20-lead 3mm 4mm QFN registered trademarks and trademarks are the property of their respective owners.

2 400kHz 5V to 40V input /12V Output Nonsynchronous Buck BoostEfficiency vs Load Current nEasily Configurable as a Synchronous Buck, Boost, SEPIC, ZETA or Nonsynchronous Buck-Boost Converter nWide input Range: to 42V (VIN Can Operate to 0V, when EXTVCC > ) nAutomatic Low Noise Burst Mode Operation nLow IQ in Burst Mode Operation (15 A Operating) nInput Voltage Regulation for High Impedance Source n100% Duty Cycle in Dropout (Buck Mode) n2A Gate Drivers (BG and TG) nAdjustable Soft-Start with One Capacitor nFrequency Programmable from 100kHz to 750kHz nCan Be Synchronized to External Clock nAvailable in 20-Lead TSSOP and 20-Lead 3mm 4mm QFN PackagesAPPLICATIONS nGeneral Purpose DC/DC Conversion nAutomotive Systems nIndustrial Supplies nSolar Panel Power F 216V, X7 RVOUT12V, (VIN >16V) (9V < VIN < 16V) (VIN < 9V)10 F 650V, X7 RVIN5V TO HD2M24m 8711 TA01aLOAD CURRENT (A) (%)8711 TA01bVIN = 5 VVIN = 12 VVIN = 24 VVIN = 36 VLT87112 Rev AFor more information CONFIGURATIONABSOLUTE MAXIMUM RATINGSVIN Voltage.

3 To 42 VBIAS Voltage .. to 42 VEXTVCC Voltage .. to 42 VBG, TG Voltage ..Note 2FB Voltage .. to Voltage .. to Voltage .. to MAX(VIN, EXTVCC)SYNC Voltage .. to Voltage .. to Note 2 CSP Voltage .. to 42V(Note 1)FE PACKAGE20-LEAD PLASTIC TSSOPTJMAX = 125 C, JA = 38 C/W, JC = 10 C/WEXPOSED PAD (PIN 21) IS GND, MUST BE SOLDERED TO PCB12345678910 TOP VIEW20191817161514131211EN/FBINFBVCSSOPM ODEISPISNINTVEEBIASTGRTSYNCNCCSPCSNEXTVC CVININTVCCNCBG21 GND2019181778 TOP VIEW21 GNDUDC PACKAGE20-LEAD (3mm 4mm) PLASTIC QFNTJMAX = 125 C, JA = 52 C/W, JC = C/WEXPOSED PAD (PIN 21) IS GND, MUST BE SOLDERED TO PCB910654321111213141516 VCSSOPMODEISPISNINTVEECSPCSNEXTVCCVININT VCCNCFBEN/FBINRTSYNCBIASTGNCBGORDER INFORMATIONLEAD FREE FINISHTAPE AND REELPART MARKING*PACKAGE DESCRIPTIONTEMPERATURE RANGELT8711 EFE#PBFLT8711 EFE#TRPBFLT8711 FE20-Lead TSSOP 40 C to 125 CLT8711 IFE#PBFLT8711 IFE#TRPBFLT8711 FE20-Lead TSSOP 40 C to 125 CLT8711 EUDC#PBFLT8711 EUDC#TRPBFLGQJ20-Lead 3mm 4mm QFN 40 C to 125 CLT8711 IUDC#PBFLT8711 IUDC#TRPBFLGQJ20-Lead 3mm 4mm QFN 40 C to 125 CConsult ADI Marketing for parts specified with wider operating temperature ranges.

4 *The temperature grade is identified by a label on the shipping more information on lead free part marking, go to: For more information on tape and reel specifications, go to: Some packages are available in 500 unit reels through designated sales channels with #TRMPBF #orderinfoCSN Voltage ..CSP to CSP + Voltage ..ISN to ISN + Voltage .. to BIASINTVCC Voltage .. to Voltage .. to Voltage .. to Junction Temperature Range LT 8711E .. 40 C to 125 C LT 8711I .. 40 C to 125 CStorage Temperature Range .. 65 C to 150 CLead Temperature (Soldering, 10 sec) ..300 CLT87113 Rev AFor more information CHARACTERISTICSPARAMETERCONDITIONSMINTYP MAXUNITSVIN Operating Voltage RangeVEXTVCC = 0V VEXTVCC = 042 42V VQuiescent Current in Normal Operation (IVIN + IEXTVCC + IBIAS)VEN/FBIN = , Not Current in Burst Mode Operation (IVIN + IEXTVCC + IBIAS)VFB = VFB_REG + 3mV1525 AQuiescent Current in Shutdown (IVIN + IEXTVCC + IBIAS)

5 VEN/FBIN = 0V12 AFB Output Regulation Voltage, VFB_REG l784 795800 800816 805mV mVFB Line VIN Pin input Bias CurrentVFB = 50050nAError Amp Transconductance I = 5 A250 mhosError Amp Voltage Gain90dBMaximum Current Sense Voltage, VCSP VCSN Minimum Duty Cycle Maximum Duty Cyclel l46 2650 3354 40mV mVSwitching Frequency, fOSCRT = RT = 247kl l675 85750 100825 115kHz kHzSwitching Frequency RangeFree-Running Synchronizingl l85 140825 750kHz kHzSYNC input Voltage input Voltage Clock Pulse Duty CycleVSYNC = 0V to 2V, fSYNC = 500kHz2080%Recommended SYNC Ratio VoltageIINTVCC = Line Regulation6V VIN 42V, VEXTVCC = 0, IINTVCC = 10mA 6V VEXTVCC 42V, VVIN = 0, IINTVCC = 10mA %/VINTVCC Load RegulationIINTVCC = 0mA to 40mA 1 2%INTVCC Maximum External Load CurrentInternal Load Current = 40mA10mAINTVCC Undervoltage LockoutINTVCC Rising INTVCC Fallingl VINTVCC Undervoltage Lockout Hysteresis500mVINTVEE Voltage, VBIAS VINTVEEIINTVEE = Undervoltage Lockout, VBIAS VINTVEEVBIAS VINTVEE Rising VBIAS VINTVEE Fallingl VINTVEE Undervoltage Lockout Hysteresis, VBIAS VINTVEE250mVBG Rise TimeCBG = (Note 4)14nsBG Fall TimeCBG = (Note 4)12nsTG Rise TimeCTG = (Note 4)11nsTG Fall TimeCTG = (Note 4)14nsBG and TG Non-Overlap TimeTG Rising to BG Rising, CBG = CTG = (Note 4)70nsBG and TG Non-Overlap TimeBG Falling to TG Falling, CBG = CTG = (Note 4)

6 70nsMinimum On-TimeCBG = CTG = The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25 C. VIN = 12V, VBIAS = 12V, unless otherwise noted (Note 3).LT87114 Rev AFor more information 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 2: Do not apply a positive or negative voltage or current source to BG, TG and INTVEE pins, otherwise permanent damage may 3: The LT8711E is guaranteed to meet performance specifications from 0 C to 125 C junction temperature. Specifications over the 40 C to 125 C operating temperature range are assured by design, PARAMETERCONDITIONSMINTYPMAXUNITSSS Charge CurrentVSS = 0V, Current Flows Out of SS pinl61015 ASS Low Detection VoltagePart Exiting Undervoltage Lockoutl6585105mVEN/FBIN Active ModeEN/FBIN Chip EnableEN/FBIN Rising EN/FBIN Fallingl VEN/FBIN Chip Enable Hysteresis30mVEN/FBIN input Voltage LowShutdown Current Limit Adjustment VoltageFull Current Limit Near Zero Current Limitl l VEN/FBIN Pin input Bias CurrentVEN/FBIN = 12Vl 50050nAEN/FBIN Amp TransconductanceVFB = mhosEN/FBIN Amp Voltage GainVFB = CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range.

7 Otherwise specifications are at TA = 25 C. VIN = 12V, VBIAS = 12V, unless otherwise noted (Note 3).characterization and correlation with statistical process controls. The LT8711I is guaranteed over the full 40 C to 125 C operating junction temperature 4: Rise and fall times are measured using 10% and 90% levels. Delay times are measured using 50% 5: This IC includes overtemperature protection that is intended to protect the device during momentary overload conditions. Junction temperature will exceed 125 C when overtemperature protection is active. Continuous operation over the specified maximum operating junction temperature may impair device AFor more information PERFORMANCE CHARACTERISTICSTA = 25 C, unless otherwise Current Limit vs Duty Cycle (CSP CSN)Maximum Current Limit vs SS (CSP CSN)Output Voltage Regulation (VFB_REG) input Voltage Regulation (EN/FBIN)EN/FBIN Chip Enable ThresholdEN/FBIN Active Mode ThresholdInput Voltage Regulation vs FB (EN/FBIN)CSN Bias CurrentISN Bias CurrentDUTY CYCLE (%)0102030405060708090100202734414855 MAX CSP - CSN (mV)8711 G01SS (V) CSP CSN (mV)8711 G02 TEMPERATURE ( C) 50 2502550751001257957967977987998008018028 03804805 VFB_REG (mV)8711 G03 TEMPERATURE ( C) 50 VOLTAGE (V)8711 G04 RISINGFALLINGTEMPERATURE ( C) 50 CHIP ENABLE (V)8711 G05 TEMPERATURE ( C) 50 ACTIVE MODE (V)8711 G06FB (V) (V)8711 G07 VCSP = VCSN = 12 VTEMPERATURE ( C)

8 50 2502550751001256080100120140160180 CSN BIAS CURRENT ( A)8711 G08 VISP = VISN=12 VTEMPERATURE ( C) 50 250255075100125100150200250300350 ISN BIAS CURRENT ( A)8711 G09LT87116 Rev AFor more information PERFORMANCE CHARACTERISTICSTA = 25 C, unless otherwise Thresholds (ISP ISN)Oscillator Frequency vs TemperatureBG Transition Time vs Cap LoadTG Transition Time vs Cap LoadMinimum Operating input VoltageINTVCC vs TemperatureINTVCC UVLO vs TemperatureINTVCC Current Limit vs VIN or EXTVCCINTVCC Dropout from VIN or EXTVCCVISN = 0 VVISN = 12 VTEMPERATURE ( C) 50 -ISN (mV)8711 G10RT = RT = 247k TEMPERATURE ( C) 50 2502550751001250100200300400500600700800 FOSC (kHz)8711 G11 RISINGFALLINGCAP LOAD (nF)0123456789100102030405060BG TRANSITION TIME (ns)8711 G12 RISINGFALLINGCAP LOAD (nF)0123456789100102030405060TG TRANSITION TIME (ns)8711 G13 RISINGFALLINGTEMPERATURE ( C) 50 OR VEXTVCC (V)8711 G14 IINTVCC = 10mATEMPERATURE ( C) 50 (V)8711 G15 RISINGFALLINGTEMPERATURE ( C) 50 (V)8711 G16 input VOLTAGE (V)510152025303540010203040506070 INTVCC CURRENT LIMIT (mA)8711 G17 INTVCC LOAD CURRENT (mA) input - INTVCC (V)8711 G18LT87117 Rev AFor more information PERFORMANCE CHARACTERISTICSTA = 25 C, unless otherwise vs TemperatureINTVEE UVLO vs TemperatureINTVEE Current Limit vs BIASINTVEE Dropout (BIAS = 6V)IQ_BURST vs VIN or EXTVCCIQ_BURST vs TemperatureIINTVEE = 10mATEMPERATURE ( C) 50 - INTVEE (V)8711 G19 RISINGFALLINGTEMPERATURE ( C) 50 INTVEE (V)8711 G20 BIAS (V)51015202530354001020304050607080 INTVEE CURRENT LIMIT (mA)8711 G21 BIAS = 6 VINTVEE LOAD CURRENT (mA) (V)8711 G22 input VOLTAGE (V)510152025303540101214161820IQ_BURST ( A)8711 G23 TEMPERATURE ( C) 50 ( A)8711 G24LT87118 Rev AFor more information FUNCTIONSEN/FBIN (Pin 1/Pin 19).

9 Enable and input Voltage Regu-lation Pin. In conjunction with the UVLO (undervoltage lockout) circuit, this pin is used to enable/disable the chip and restart the soft-start sequence. The EN/FBIN pin is also used to limit the switching regulator current to avoid collapsing the input supply. Drive below to disable the chip with very low quiescent current. Drive above (typical) to activate the chip. The commanded input cur-rent will adjust when the EN/FBIN pin voltage is between and Drive above (typical) to activate switching with no reduction in input current and restart the soft-start sequence. See the Block Diagram and Applica-tions section for more information. Do not float this (Pin 2/Pin 20): Feedback input Pin. The LT8711 regu-lates the FB pin to Connect the feedback resistor divider tap to this (Pin 3/Pin 1): Error Amplifier Output Pin. Tie external compensation network to this (Pin 4/Pin 2): Soft Start Pin.

10 Place a soft-start capaci-tor here. Upon start-up, the SS pin will be charged by a 410k resistor to about During an overtemperature or UVLO condition, the SS pin will be quickly discharged to reset the part. Once those conditions are clear, the part will attempt to (Pin 5/Pin 3): Topology Selection Pin. Tie this pin to ground to select buck/ZETA mode. Tie to INTVCC to select SEPIC/boost mode. Tie to a 100pF capacitor to GND to select nonsynchronous buck-boost & ISN (Pins 6 & 7/ Pins 4 & 5): Current Sense Posi-tive and Negative input Pins respectively. Kelvin connect ISP and ISN pins to a sense (Pin 8/Pin 6): 5V Below BIAS LDO Regulator Pin. Must be locally bypassed with a minimum capacitance of F to BIAS. This pin sets the bottom rail for the TG gate driver. The TG gate driver can begin switching when BIAS INTVEE exceeds (typical).BIAS (Pin 9/Pin 7): Power Supply for the TG PFET Driver.