LT8551 Multiphase Boost Converter Expander with Internal Gate Drivers FEATURES DESCRIPTION n Expands Up to 4 Phases per Chip The LT 8551 is a multiphase expander for synchronous n Up to 80V Input or Output Voltage boost DC/DC converters. It operates in tandem with any n Cascade with Multiple Chips for High Current synchronous boost DC/DC converter to increase the load Applications current capability by adding additional phases, which are n Supports Up to 18 Distinct Phases from 20 to 180 clocked out-of-phase to reduce ripple current and filtering n Phases Can Share Phase Angle capacitance. It easily adds phases without the need to n Excellent DC and Transient Current Sharing route sensitive feedback and control signals. n Phase-Lockable Fixed Frequency 125kHz to 1MHz The LT8551 integrates 5V gate drivers and can support up n Supports Bidirectional Current Flow to four boost phases per device. Multiple LT8551 devices n R or DCR Current Sensing SENSE can be used for up to 18 phases. It accurately monitors n Eliminates the Need to Route Sensitive Feedback and and adjusts the current of each channel to achieve excel- Control Signals. lent DC and transient current sharing. n 52-Lead (7mm 8mm) QFN Package The LT8551 operates over a fixed frequency from 100kHz to 1MHz or can be synchronized to an external clock. APPLICATIONS All registered trademarks and trademarks are the property of their respective owners. Protected n High Current Distributed Power Systems by U.S. patents, including 9077244. n Telecom, Datacom, and Storage Systems n Industrial and Automotive TYPICAL APPLICATION 24V/25A Step-Up Expander System SENSE + SENSE INTV V BOOST CC IN LTC3769 TG SW INTV RUN PLLIN/MODE BG CC REG V OUT 24V/25A V FOLLOWS V OUT IN WHEN V > 24V IN REGSNS ENOUT CLK1 TGSR TGSH TGSL BGSH ISP REG POWER STAGE 1 V ISN IN V IN 5V TO 24V TG1 LT8551 PINS NOT SHOWN REGIS BST1 IN THIS CIRCUIT: BST2, BST3, BST4, TG2, TG3, TG4, REGDRV SW1 SW2, SW3, SW4, BG2, BG3, BG4, ISN1 REG ISP2, ISP3, ISP4, ISN2, ISN3, ISN4 ISP1 SYNC, PHS1, PHS2, PHS3, MODE, V LT8551 IN TGBUF, BGBUF, CLK2, IAMPP, IAMPN, V CC SHDN, RT/MS, ILIM BG1 GND POWER STAGE 2 PINS FOR POWER POWER STAGE 3 STAGES 2,3,4 POWER STAGE 4 8551 TA01a Rev 0 1 Document Feedback For more information www.analog.comLT8551 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) TOP VIEW SW1/2/3/4 (Note 5)..80V ISP1/2/3/4, ISN1/2/3/4, ISP, ISN, V , IN REGIS, REGDRV Voltage (Note 2) ........0.3V to 80V 52 51 50 49 48 47 46 45 44 43 42 41 SHDN Voltage0.3V to 70V BG4 1 40 REGSNS TGSL Voltage3V to 80V BG3 2 39 ISP4 TGSH Voltage3V to 86V REG 3 38 ISN4 SW3 4 37 ISP2 TG1/2/3/4, BST1/2/3/4, TGSR Voltage .... 0.3V to 86V TG3 5 36 ISN2 BG1/2/3/4, RT/MS, SYNC, PHS1/2/3, CLK1/2, BST3 6 35 ISP REGSNS, IAMPP, ILIM, BGSH, BGBUF, TGBUF, BST2 7 34 ISN 53 ENOUT, MODE, V , REG, (BSTSW)1/2/3/4, CC GND TG2 8 33 IAMPP (TGSW)1/2/3/4, (V REGDRV), IN SW2 9 32 IAMPN (TGSRTGSL), (TGSHTGSL) Voltage .. 0.3V to 6.0V BG2 10 31 SHDN IAMPN Voltage 0.6V to 0.6V BG1 11 30 MODE BGBUF 12 29 V (ISPISN)1/2/3/4, (ISPISN) Voltage ... 0.3V to 0.3V CC TGBUF 13 28 ENOUT Operating Junction Temperature Range (Note 3) BST1 14 27 ILIM LT8551E ............................................. 40C to 125C 15 16 17 18 19 20 21 22 23 24 25 26 LT8551I .............................................. 40C to 125C Storage Temperature Range .................. 65C to 150C UKG PACKAGE 52-LEAD (7mm 8mm) PLASTIC QFN T = 125C, = 31C/W, = 2C/W JMAX JA JC EXPOSED PAD (PIN 53) IS GND, MUST BE SOLDERED TO PCB ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LT8551EUKG PBF LT8551EUKG TRPBF 8551 52-Pin (7mm 8mm) Plastic QFN 40C to 125C LT8551IUKG PBF LT8551IUKG TRPBF 8551 52-Pin (7mm 8mm) Plastic QFN 40C to 125C 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 0 2 For more information www.analog.com TG1 BST4 SW1 TG4 TGSR SW4 TGSH V IN TGSL REGDRV CLK2 REGIS CLK1 ISP3 BGSH ISN3 SYNC ISN1 PHS2 ISP1 PHS1 NC RT/MS PHS3