LT3781
PRODUCTIONBootstrap Start Dual Transistor Synchronous Forward Controller
- Part Models
- 4
- 1ku List Price
- Starting From $8.29
Overview
- 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
The LT3781 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.
Applications
- Isolated Telecommunication Systems
- Personal Computers and Peripherals
- Distributed Power Step-Down Converters
- Lead Acid Battery Backup Systems
- Automotive and Heavy Equipment
Documentation
Data Sheet 1
User Guide 5
Design Note 2
Technical Articles 1
ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal. View our quality and reliability program and certifications for more information.
| Part Model | Pin/Package Drawing | Documentation | CAD Symbols, Footprints, and 3D Models |
|---|---|---|---|
| LT3781EG#PBF | 20-Lead SSOP | ||
| LT3781EG#TRPBF | 20-Lead SSOP | ||
| LT3781IG#PBF | 20-Lead SSOP | ||
| LT3781IG#TRPBF | 20-Lead SSOP |
| Part Models | Product Lifecycle | PCN |
|---|---|---|
|
Aug 6, 2022 - 22_0171 Laser Top Mark Conversion for SSOP Packages Assembled in PNG |
||
| LT3781EG#PBF | PRODUCTION | |
| LT3781EG#TRPBF | PRODUCTION | |
| LT3781IG#PBF | PRODUCTION | |
| LT3781IG#TRPBF | PRODUCTION | |
This is the most up-to-date revision of the Data Sheet.
Software Resources
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LTspice
Models for the following parts are available in LTspice:
- LT3781
LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.
Evaluation Kits
LT3710EFE LT3781EG LTC1698EGN | Dual Output Isolated Power Supply, 36V to 72V Input, 3.3VOUT @ 10A, 1.8/2.5VOUT @ 10A
Resources
LT3781EG LTC1698EGN | Isolated Power Supply, 36V to 72V Input, 5VOUT @ 30A
Resources
LT3781EG, LTC1698EGN, LT1783CS5 | Isolated Synchronous, Forward Converter, VIN=36V-72V, VOUT=3.3V @ 15A
Resources
LT3804EFE LT3781EG LTC1693-1IS8 | Dual Output Isolated Power Supply, 36V to 72V Input, +Vo1 = 3.3V @ 15A, +Vo2 = 1.8V @ 15A
Resources
LT3781EG LTC1698EGN LT1783CS5 | Isolated Synchronous Forward Converter, +VIN = 36V to 72V, +VOUT = 2.5V @ 20A, Quarter Brick Footprint
Resources
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