Datasheet LT8708 (Analog Devices) - 64

LT8708
TYPICAL APPLICATION Supercapacitor Backup Supply Using CCM
TO LOADS (REGULATE TO 11V WHEN IN BACKUP) D L1 IN 25mΩ 2.2μH M1 M4 25mΩ VIN VOUT 12V + + 15V C M2 M3 C IN1 OUT1 COUT2 CIN2 TO DIODE 10Ω TO DIODE C 1µF SC 1.2k DB1 DB2 ×6 ×6 1nF 2Ω 5mΩ 2Ω 162k 71.5k 1nF 0.22µF 0.22µF 10Ω 100Ω 100Ω 1µF 20k 20k TG1 BOOST1 SW1 BG1 CSP CSN GND BG2 SW2 BOOST2 TG2 115k CSNIN CSPOUT 4.7µF 4.7µF CSPIN CSNOUT VINCHIP EXTVCC 200k SHDN FBOUT FBIN 4.7µF INTVCC 150k LT8708 VINHIMON GATEVCC 10k VOUTLOMON IMON_OP 4.7µF 4Ω 20k 50k SWEN ICN LD033 ICP LDO33 50k IMON_INP 6.8nF RVSOFF 22nF D IMON_ON B1 DB2 17.4k 26.7k DIR IMON_INN TO TO MODE VC RT SS SYNC CLKOUT BOOST1 BOOST2 8708 TA02 15k 22nF 17.4k 6.8nF 124k 1µF 17.4k 220pF 5.6nF 350kHz DIN: APPROPRIATE 2A SCHOTTKY DIODE OR IDEAL DIODE M1–M4: INFINEON BSC050NE2LS SEE MORE DETAILS OF THIS APPLICATION ON PAGE 61. SUCH AS LTC4358, LTC4412, LTC4352, ETC. CIN1, COUT2: 220μF, 35V 35HVP220M DB1, DB2: CENTRAL SEMI CMMR1U-02-LTE CIN2, COUT1: 22µF, 25V, TDK C4532X741E226M L1: 2.2μH, VISHAY IHLP-5050CE-01-2R2-M-01 CSC: 60F, 2.5V COOPER BUSSMAN HB1840-2R5606-R
RELATED PARTS PART NUMBER DESCRIPTION COMMENTS
LT8708-1 80V Synchronous 4-Switch Buck-Boost DC/DC 2.8V (Need EXTVCC > 6.4V) ≤ VIN ≤ 80V,1.3V ≤ VOUT ≤ 80V, 5mm × 8mm QFN-40 Slave Controller for LT8708 Multiphase System LT8705A 80V VIN and VOUT Synchronous 4-Switch Buck- 2.8V ≤ VIN ≤ 80V, Input and Output Current Monitor, 5mm × 7mm QFN-38 and Boost DC/DC Controller TSSOP-38 Packages LTC®3779 150V VIN and VOUT Synchronous 4-Switch Buck- 4.5V ≤ VIN ≤ 150V, 1.2V ≤ VOUT ≤ 150V, Up to 99% Efficiency Drives Logic-Level Boost Controller or STD Threshold MOSFETs, TSSOP-38 Package LTC7813 60V Low IQ Synchronous Boost+Buck Controller 4.5V (Down to 2.2V After Start-Up) ≤ VIN ≤ 60V, Boost VOUT Up to 60V, Low EMI and Low Input/Output Ripple 0.8V ≤ Buck VOUT ≤ 60V, IQ = 29µA, 5mm × 5mm QFN-32 Package LTC3899 60V, Triple Output, Buck/Buck/Boost Synchronous 4.5V (Down to 2.2V after Start-Up) ≤ VIN ≤ 60V, VOUT Up to 60V, Controller with 29µA Burst Mode IQ Buck VOUT Range: 0.8V to 60V, Boost VOUT Up to 60V LTM®8056 58VIN, Buck-Boost µModule Regulator, Adjustable 5V ≤ VIN ≤ 58V, 1.2V ≤ VOUT ≤ 48V, 15mm × 15mm × 4.92mm BGA Package Input and Output Current Limiting LTC3895/ 150V Low IQ, Synchronous Step-Down 4V ≤ VIN ≤ 140V, 150V ABS Max, PLL Fixed Frequency 50kHz to 900kHz, LTC7801 DC/DC Controller with 100% Duty Cycle 0.8V ≤ VOUT ≤ 60V, Adjustable 5V to 10V Gate Drive, IQ = 40μA, 4mm × 5mm QFN-24, TSSOP-24, TSSOP-38(31) Packages LTC3871 Bidirectional Multiphase DC/DC Synchronous Buck VIN/VOUT Up to 100V, Ideal for High Power 48V/12V Automotive Battery or Boost On-Demand Controller Applications LTC7103 105V, 2.3A, Low EMI Synchronous 4.4V ≤ VIN ≤105V, 1V ≤ VOUT ≤ VIN, IQ = 2µA, Fixed Frequency 200kHz, Step-Down Regulator 5mm × 6mm QFN Package Rev 0 64 D16897-0-6/18(0) www.analog.com For more information www.analog.com © ANALOG DEVICES, INC. 2018 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Pin Configuration Electrical Characteristics Typical Performance Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Typographical Conventions Start-Up Start-Up: SHDN Pin Start-Up: SWEN Pin Start-Up: Soft-Start of Switching Regulator Control Overview Power Switch Control Switch Control: Buck Region (VIN >> VOUT) Switch Control: Buck-Boost (VIN ≅ VOUT) Switch Control: Boost Region (VIN << VOUT) Switch Control: Soft-Start Uni and Bidirectional Conduction Bidirectional Conduction: CCM Unidirectional Conduction: DCM Unidirectional Conduction: HCM Unidirectional Conduction: Burst Mode Error Amplifiers VOUT Regulation and Sensing VOUT: Regulation VOUT: Above Regulation VOUT: Below Regulation and Undervoltage VIN Regulation and Sensing VIN: Regulation VIN: Above Regulation and Overvoltage VIN: Below Regulation Current Monitoring and Limiting Monitoring and Limiting: IMON Pins Monitoring: ICP and ICN Pins INTVCC/EXTVCC/GATEVCC/LDO33 Power CLKOUT and Temperature Sensing Applications Information Verify the Power Flow Conditions Operating Frequency Selection Internal Oscillator SYNC Pin and Clock Synchronization CLKOUT Pin and Clock Synchronization Inductor Current Sensing and Slope Compensation RSENSE Selection and Maximum Current RSENSE Selection: Max RSENSE in the Boost Region RSENSE Selection: Max RSENSE in the Buck Region RSENSE Selection: Final RSENSE Value RSENSE Filtering Inductor (L) Selection L Selection: Load Current in Buck and Boost Regions L Selection: Subharmonic Oscillations L Selection: Maximum Current Rating Power MOSFET Selection CIN and COUT Selection Schottky Diode (D1, D2, D3, D4) Selection Topside MOSFET Driver Supply (CB1, DB1, CB2, DB2) Top Driver: Boost Cap Charge Control Block Top Driver: Boost Diodes DB1 and DB2 VINHIMON, VOUTLOMON and RVSOFF IIN and IOUT Current Monitoring and Limiting Loop Compensation INTVCC Regulators and EXTVCC Connection LDO33 Regulator Voltage Lockouts Junction Temperature Measurement Thermal Shutdown Efficiency Considerations Circuit Board Layout Checklist Hot Plugging Considerations Design Example Typical Applications Package Description Typical Application Related Parts