LTC3871/LTC3871-1 Bidirectional PolyPhase Synchronous Buck or Boost Controller FEATURES DESCRIPTION n Unique Architecture Allows Dynamic Regulation of The LTC 3871/LTC3871-1 is a high performance bidi- Input Voltage, Output Voltage or Current rectional buck or boost switching regulator controller n V Voltages Up to 100V that operates in either buck or boost mode on demand. HIGH n V Voltages Up to 30V It regulates in buck mode from V -to-V and boost LOW HIGH LOW n Synchronous Rectification: Up to 97% Efficiency mode from V -to-V depending on a control signal, LOW HIGH n ADI-Proprietary Advanced Current Mode Control making it ideal for 48V/12V automotive dual battery sys- n 1% Voltage Regulation Accuracy Over Temperature tems. An accurate current programming loop regulates n Accurate, Programmable Output Current Monitoring the maximum current that can be delivered in either direc- and Regulation for Both Buck and Boost Operation tion. The LTC3871/LTC3871-1 allows both batteries to n Selectable Buck and Boost Current Sense Limits supply energy to the load simultaneously by converting n Programmable DRV /EXTV Optimizes Efficiency energy from one battery to the other. CC CC n Programmable V UV and OV Thresholds HIGH Its proprietary constant-frequency current mode n Programmable V OV Threshold LOW architecture enhances the signal-to-noise ratio enabling n Phase-Lockable Frequency: 60kHz to 460kHz low noise operation and provides excellent current n Multiphase/Multi-ICs Operation Up to 12 Phases matching between phases. Additional features include n Selectable CCM/DCM Modes discontinuous or continuous mode of operation, OV/UV n Thermally Enhanced 48-Lead LQFP Package monitors, independent loop compensation for buck and boost operation, accurate output current monitoring and APPLICATIONS overcurrent protection. The LTC3871 and LTC3871-1 n Automotive 48V/12V Dual Battery Systems have different current limit foldback characteristics. n Backup Power Systems All registered trademarks and trademarks are the property of their respective owners. TYPICAL APPLICATION High Efficiency Bidirectional Charger/Power Supply V HIGH 26V TO 58V Buck-to-Boost Transition OV HIGH EXTV CC UV HIGH VFB LOW BUCK BOOST BUCK SNS1 ITH HIGH + SNSD1 V LOW + 5V/DIV SNSA1 BST1 DRV CC I ITH L LOW 5A/DIV LTC3871/ TG1 SS LTC3871-1 V HIGH SW1 V LOW 10V/DIV 12V BG1 BATTERY BUCK BOOST BUCK SW VFB HIGH 50V/DIV IMON SNS2 3871 TA01b FREQ + SNSD2 50/DIV V LOW + SNSA2 BST2 DRV CC OV LOW TG2 DRV CC SW2 V5 BG2 PINS NOT SHOWN IN THIS CIRCUIT: 3871 TA01a CLKOUT, DRVSET, FAULT, ILIM, MODE, PHSMD, RUN, SETCUR AND SYNC. Rev. B 1 Document Feedback For more information www.analog.com SGND PGATE PGND V HIGHLTC3871/LTC3871-1 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) V ....................................................... 0.3V to 100V HIGH TOP VIEW Top Side Driver Voltages (BOOST1, BOOST2) ..............................0.3V to 111V Switch Voltage (SW1, SW2) ....................... 5V to 100V Current Sense Voltages + + (SNSA , SNS , SNSD Channels 1 and 2) ... 0.3V to 34V, SS 1 36 BG1 2V to 34V for < 100sec VFB 2 35 PGND1 LOW ITH 3 34 N/C LOW (BOOST1-SW1), (BOOST2-SW2) ...........0.3V to 11V ITH 4 33 PGATE HIGH VFB 5 32 N/C HIGH EXTV .....................................................0.3V to 34V, CC V5 6 31 V HIGH 49 0.8V to 34V for < 100sec SGND 7 30 N/C GND OV 8 29 DRV HIGH CC DRV ........................................................0.3V to 11V CC UV 9 28 SGND HIGH OV 10 27 EXTV LOW CC VFB , VFB ........................................ 0.3V to V5 HIGH LOW IMON 11 26 PGND2 SETCUR 12 25 BG2 MODE, SS Voltages ...................................... 0.3V to V5 RUN ............................................................. 0.3V to 6V FAULT, SETCUR, Voltages ........................... 0.3V to V5 ILIM, DRVSET, BUCK Voltages .................... 0.3V to V5 OV , UV , OV Voltages ................ 0.3V to 6V HIGH HIGH LOW SYNC, PHSMD Voltages .............................. 0.3V to V5 LXE PACKAGE 48-LEAD (7mm 7mm) PLASTIC LQFP Operating Junction Temperature T = 150C, = 36C/W Range (Notes 2, 3) ............................. 40C to 150C JMAX JA EXPOSED PAD (PIN 49) IS GND, MUST BE SOLDERED TO PCB Storage Temperature Range .................. 65C to 150C DRV /EXTV Peak Current ...............................100mA CC CC ORDER INFORMATION LEAD FREE FINISH PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3871ELXE PBF LTC3871 48-Lead (7mm 7mm) Plastic LQFP 40C to 125C LTC3871ILXE PBF LTC3871 48-Lead (7mm 7mm) Plastic LQFP 40C to 125C LTC3871HLXE PBF LTC3871 48-Lead (7mm 7mm) Plastic LQFP 40C to 150C LTC3871ELXE-1 PBF LTC3871-1 48-Lead (7mm 7mm) Plastic LQFP 40C to 125C LTC3871ILXE-1 PBF LTC3871-1 48-Lead (7mm 7mm) Plastic LQFP 40C to 125C LTC3871HLXE-1 PBF LTC3871-1 48-Lead (7mm 7mm) Plastic LQFP 40C to 150C Contact the factory for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. Tape and reel specifications. Some packages are available in 500 unit reels through designated sales channels with TRMPBF suffix. Rev. B 2 For more information www.analog.com + + 48 SNSA1 SNSA2 13 47 SNS1 SNS2 14 + + 46 SNSD1 SNSD2 15 45 PHSMD BUCK 16 44 MODE ILIM 17 43 FREQ RUN 18 42 SYNC FAULT 19 41 CLKOUT DRVSET 20 40 N/C N/C 21 39 TG1 TG2 22 38 SW1 SW2 23 37 BOOST1 BOOST2 24