LT8550 4-Phase DC/DC Expander with Internal Gate Drivers for Buck Converters FEATURES DESCRIPTION n Expands Up to Four Phases per Chip The LT 8550 is a multiphase expander for synchronous n Up to 80V Input or Output Voltage buck DC/DC converters. It operates in tandem with any n Cascade with Multiple Chips for Very High Current buck DC/DC converter to increase the load current capa- Applications bility by adding additional phases, which are clocked out- n Supports Up to 18 Distinct Phases from 20 to 180 of-phase to reduce ripple current and filtering capacitance. n Phases Can Share Phase Angle It easily adds phases without the need to route sensitive n Excellent DC and Transient Current Sharing feedback and control signals. n Phase-Lockable Fixed Frequency 125kHz to 1MHz The LT8550 integrates gate drivers and can support up n Supports Bidirectional Current Flow to four buck phases per device. Multiple LT8550s can n R or DCR Current Sensing SENSE be used for up to 18 phases. It accurately monitors and n Eliminates the Need to Route Sensitive Feedback and adjusts the current of each channel to achieve excellent Control Signals DC and transient current sharing. n 52-Lead (7mm 8mm) QFN Package The LT8550 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 by U.S. Patents, including 9077244. High Current Distributed Power Systems n Telecom, Datacom, and Storage Systems n Industrial and Automotive TYPICAL APPLICATION 10V/100A Step-Down Phase Expander System CTRL1 FB 10 100k SENSEN 12.1k 33nF 10 V SENSEP REF V IN 2.2F R HOT 88.7k 45.3k LT3741 + HG 47F 100F CTRL2 2 0.22F R NTC CBOOT 680k 1.3H 2.5m VC SW 10k V 47F 150F IN RT SS EN/UVLO SYNC VCC INT GND LG 2 2 4.7nF REG 22F 10nF 1nF 47k 1F 200k 1 V OUT 10V/100A MAX V IN V ENOUT CLK1 REGSNS TGSR TGSH BGSH TGSL IN 10 14V TO ISP 36V 4.7F 137k 1nF ISN SHDN 24k REGIS V IN POWER STAGE 1 MP REGDRV + TG1 47F REG 100F 2 REG REG 0.22F REG PHS1 10F PHS2 BST1 1 1.3H 2.5m ILIM LT8550 SW1 V CC 47F 150F PHS3 4.7F BG1 2 2 SYNC 10 RT/MS ISP1 IAMPP 62k 1nF 220pF ISN1 PINS NOT SHOWN IAMPN V IN THIS CIRCUIT: OUT POWER STAGE 2 ISP2, ISN2, BST2, TG2, SW2, BG2 PINS FOR V OUT ISP3, ISN3, BST3, TG3, SW3, BG3 POWER POWER STAGE 3 ISP4, ISN4, BST4, TG4, SW4, BG4, V STAGE2,3,4 OUT 8550 TA01a GND POWER STAGE 4 CLK2, TGBUF, BGBUF, MODE Rev. 0 1 Document Feedback For more information www.analog.comLT8550 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) TOP VIEW SW1/2/3/4 ...................................................80V (Note 5) ISP1/2/3/4, ISN1/2/3/4, ISP, ISN, V , REGIS, REGDRV Voltage (Note 2) ... 0.3V to 80V IN 52 51 50 49 48 47 46 45 44 43 42 41 SHDN Voltage ............................................ 0.3V to 70V BG4 1 40 REGSNS TGSL Voltage ................................................ 3V to 80V BG3 2 39 ISN4 REG 3 38 ISP4 TGSH Voltage ................................................ 3V to 86V SW3 4 37 ISN2 TG1/2/3/4, BST1/2/3/4, TGSR Voltage ...... 0.3V to 86V TG3 5 36 ISP2 BG1/2/3/4, RT/MS, SYNC, PHS1/2/3, BST3 6 35 ISN CLK1/2, REGSNS, IAMPP, ILIM, BGSH, BST2 7 34 ISP 53 BGBUF, TGBUF, ENOUT, MODE, V , GND CC TG2 8 33 IAMPP REG, (BST-SW)1/2/3/4, (TG-SW)1/2/3/4, SW2 9 32 IAMPN BG2 10 31 SHDN (V -REGDRV), (TGSR-TGSL), IN 30 BG1 11 MODE (TGSH-TGSL) Voltage .......................... 0.3V to 6.0V BGBUF 12 29 V CC IAMPN Voltage .......................................... 0.6V to 0.6V TGBUF 13 28 ENOUT (ISP-ISN)1/2/3/4, (ISP-ISN) Voltage ......... 0.3V to 0.3V BST1 14 27 ILIM Operating Junction Temperature Range (Note 3) 15 16 17 18 19 20 21 22 23 24 25 26 LT8550E ............................................ 40C to 125C LT8550I ............................................. 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 LT8550EUKG PBF LT8550EUKG TRPBF 8550 52-PIN (7mm 8mm) Plastic QFN 40C to 125C LT8550IUKG PBF LT8550IUKG TRPBF 8550 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 ISN3 BGSH ISP3 SYNC ISP1 PHS2 ISN1 PHS1 NC RT/MS PHS3