LT3781 Bootstrap Start Dual Transistor Synchronous Forward Controller

The LT®3781 controller simplifies the design of high power synchronous dual transistor forward DC/DC converters. The part employs fixed frequency current mode control and supports both isolated and nonisolated topologies. The IC drives external N-channel power MOSFETs and operates with input voltages up to 72V.

The LT3781 is ideal for output derived power schemes, through the use of a large undervoltage lockout hysteresis range. The part is also equipped with an 18V VCC shunt regulator, which prevents exceeding absolute maximum ratings while in trickle start applications.

The LT3781’s operating frequency is programmable and can be synchronized up to 350kHz. Switch phase is also controlled during synchronized operation to accommodate multiple-converter systems. Internal logic guarantees 50% maximum duty cycle operation to prevent transformer saturation.

The LT3781 is available in a 20-lead SSOP package

产品特点 Features

High Voltage Operation up to 72V
Synchronizable Operating Frequency and Output Switch Phase for Multiple Controller Systems
Synchronous Switch Output
Undervoltage Lockout Protection with 6V Hysteresis for Self-Biased Power
Fixed Frequency Operation to 350kHz
Local 1% Voltage Reference
Input Overvoltage Protection
Low Start-Up Current
Programmable Start Inhibit for Power Supply Sequencing and Protection
Optocoupler Support
Soft-Start Control

参数

应用

Isolated Telecommunication Systems
Personal Computers and Peripherals
Distributed Power Step-Down Converters
Lead Acid Battery Backup Systems
Automotive and Heavy Equipment

典型应用图

LT3781 订购信息和价格参考Package Variations and Pricing

器件型号	封装	引脚	温度	价格 (以 1 ~ 99 片为批量)	价格 (以 1000 片为批量) *
LT3781EG	SSOP	20	E	$7.14	$4.95
LT3781EG#PBF	SSOP	20	E	$7.14	$4.95
LT3781EG#TR	SSOP	20	E		$5.05
LT3781EG#TRPBF	SSOP	20	E		$5.05
LT3781IG	SSOP	20	I	$7.86	$5.45
LT3781IG#PBF	SSOP	20	I	$7.86	$5.45
LT3781IG#TR	SSOP	20	I		$5.55
LT3781IG#TRPBF	SSOP	20	I		$5.55

LT3781 数据手册及相关资料下载

数据手册(英文) : LT3781 - 'Bootstrap' Start Dual Transistor Synchronous Forward Controller.PDF
可靠性数据 : R352 Reliability Data .PDF