Datasheet LT8550 (Analog Devices)
| Manufacturer | Analog Devices |
| Description | 4-Phase DC/DC Expander with Internal Gate Drivers for Buck Converters |
| Pages / Page | 34 / 1 — FEATURES. DESCRIPTION. Expands Up to Four Phases per Chip. Up to 80V … |
| File Format / Size | PDF / 3.2 Mb |
| Document Language | English |
FEATURES. DESCRIPTION. Expands Up to Four Phases per Chip. Up to 80V Input or Output Voltage
Model Line for this Datasheet
Text Version of Document
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 LT8550’s can n RSENSE or DCR Current Sensing 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
APPLICATIONS
to 1MHz, or can be synchronized to an external clock. 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 10Ω 100k SENSEN 12.1k 33nF 10Ω V SENSEP REF VIN 2.2µF RHOT 88.7k 45.3k LT3741 HG 47µF + CTRL2 0.22µF ×2 100µF RNTC CBOOT 680k 1.3µH VC 2.5mΩ SW 10k VIN RT SS EN/UVLO SYNC VCC_INT GND LG 47µF 150µF ×2 ×2 4.7nF 10nF REG 22µF 1nF 47k 1µF 200k 1Ω VOUT V 10V/100A MAX IN V 14V TO IN ENOUT CLK1 REGSNS TGSR TGSH BGSH TGSL 10Ω 36V 4.7µF ISP 137k 1nF ISN SHDN 24k REGIS VIN POWER STAGE 1 MP REGDRV TG1 47µF + REG 100µF ×2 REG REG REG 0.22µF 10µF PHS1 PHS2 BST1 1Ω 1.3µH ILIM 2.5mΩ LT8550 SW1 VCC 4.7µF PHS3 BG1 47µF 150µF ×2 ×2 SYNC 10Ω RT/MS ISP1 IAMPP 62k 1nF 220pF ISN1 PINS NOT SHOWN IAMPN V IN THIS CIRCUIT: POWER STAGE 2 OUT ISP2, ISN2, BST2, TG2, SW2, BG2 PINS FOR V ISP3, ISN3, BST3, TG3, SW3, BG3 POWER POWER STAGE 3 OUT ISP4, ISN4, BST4, TG4, SW4, BG4, STAGE2,3,4 V GND OUT 8550 TA01a POWER STAGE 4 CLK2, TGBUF, BGBUF, MODE Rev. 0 Document Feedback For more information www.analog.com 1
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 LT8550’s can n RSENSE or DCR Current Sensing 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
APPLICATIONS
to 1MHz, or can be synchronized to an external clock. 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 10Ω 100k SENSEN 12.1k 33nF 10Ω V SENSEP REF VIN 2.2µF RHOT 88.7k 45.3k LT3741 HG 47µF + CTRL2 0.22µF ×2 100µF RNTC CBOOT 680k 1.3µH VC 2.5mΩ SW 10k VIN RT SS EN/UVLO SYNC VCC_INT GND LG 47µF 150µF ×2 ×2 4.7nF 10nF REG 22µF 1nF 47k 1µF 200k 1Ω VOUT V 10V/100A MAX IN V 14V TO IN ENOUT CLK1 REGSNS TGSR TGSH BGSH TGSL 10Ω 36V 4.7µF ISP 137k 1nF ISN SHDN 24k REGIS VIN POWER STAGE 1 MP REGDRV TG1 47µF + REG 100µF ×2 REG REG REG 0.22µF 10µF PHS1 PHS2 BST1 1Ω 1.3µH ILIM 2.5mΩ LT8550 SW1 VCC 4.7µF PHS3 BG1 47µF 150µF ×2 ×2 SYNC 10Ω RT/MS ISP1 IAMPP 62k 1nF 220pF ISN1 PINS NOT SHOWN IAMPN V IN THIS CIRCUIT: POWER STAGE 2 OUT ISP2, ISN2, BST2, TG2, SW2, BG2 PINS FOR V ISP3, ISN3, BST3, TG3, SW3, BG3 POWER POWER STAGE 3 OUT ISP4, ISN4, BST4, TG4, SW4, BG4, STAGE2,3,4 V GND OUT 8550 TA01a POWER STAGE 4 CLK2, TGBUF, BGBUF, MODE Rev. 0 Document Feedback For more information www.analog.com 1
