LT3781
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LT3781

Bootstrap Start Dual Transistor Synchronous Forward Controller

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Info: : PRODUCTION tooltip
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Part Details
Part Models 4
1ku List Price Starting From $6.55
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
Additional Details
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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
Part Models 4
1ku List Price Starting From $6.55

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Documentation

Documentation

Part Model Pin/Package Drawing Documentation CAD Symbols, Footprints, and 3D Models
LT3781EG#PBF
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LT3781IG#PBF
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LT3781IG#TRPBF
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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

Filter by Model

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Part Models

Product Lifecycle

PCN

Aug 6, 2022

- 22_0171

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Laser Top Mark Conversion for SSOP Packages Assembled in PNG

LT3781EG#PBF

PRODUCTION

LT3781EG#TRPBF

PRODUCTION

LT3781IG#PBF

PRODUCTION

LT3781IG#TRPBF

PRODUCTION

Software & Part Ecosystem

Software & Part Ecosystem

Evaluation Kit

Evaluation Kits 5

reference details image

DC467A

LT3781EG LTC1698EGN | Isolated Power Supply, 36V to 72V Input, 5VOUT @ 30A

reference details image

DC448A

LT3710EFE LT3781EG LTC1698EGN | Dual Output Isolated Power Supply, 36V to 72V Input, 3.3VOUT @ 10A, 1.8/2.5VOUT @ 10A

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DC448A

LT3710EFE LT3781EG LTC1698EGN | Dual Output Isolated Power Supply, 36V to 72V Input, 3.3VOUT @ 10A, 1.8/2.5VOUT @ 10A

LT3710EFE LT3781EG LTC1698EGN | Dual Output Isolated Power Supply, 36V to 72V Input, 3.3VOUT @ 10A, 1.8/2.5VOUT @ 10A

Product Detail

DC448A Demo Board for:

LT3710 Secondary Side Synchronous Post Regulator

LT3781 Bootstrap Start Dual Transistor Synchronous Forward Controller

reference details image

DC617A

LT3781EG LTC1698EGN LT1783CS5 | Isolated Synchronous Forward Converter, +VIN = 36V to 72V, +VOUT = 2.5V @ 20A, Quarter Brick Footprint

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DC617A

LT3781EG LTC1698EGN LT1783CS5 | Isolated Synchronous Forward Converter, +VIN = 36V to 72V, +VOUT = 2.5V @ 20A, Quarter Brick Footprint

LT3781EG LTC1698EGN LT1783CS5 | Isolated Synchronous Forward Converter, +VIN = 36V to 72V, +VOUT = 2.5V @ 20A, Quarter Brick Footprint

Product Detail

DC617A Demo Board for:

LT1783 1.25MHz, Over-The-Top Micropower, Rail-to-Rail Input and Output Op Amp in SOT-23

LTC1698 Isolated Secondary Synchronous Rectifier Controller

LT3781 Bootstrap Start Dual Transistor Synchronous Forward Controller

reference details image

DC479A

LT3781EG, LTC1698EGN, LT1783CS5 | Isolated Synchronous, Forward Converter, VIN=36V-72V, VOUT=3.3V @ 15A

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DC479A

LT3781EG, LTC1698EGN, LT1783CS5 | Isolated Synchronous, Forward Converter, VIN=36V-72V, VOUT=3.3V @ 15A

LT3781EG, LTC1698EGN, LT1783CS5 | Isolated Synchronous, Forward Converter, VIN=36V-72V, VOUT=3.3V @ 15A

Product Detail

DC479A Demo Board for:
LT1783 1.25MHz, Over-The-Top Micropower, Rail-to-Rail Input and Output Op Amp in SOT-23
LTC1698 Isolated Secondary Synchronous Rectifier Controller
LT3781 Bootstrap Start Dual Transistor Synchronous Forward Controller


 


reference details image

DC610A

LT3804EFE LT3781EG LTC1693-1IS8 | Dual Output Isolated Power Supply, 36V to 72V Input, +Vo1 = 3.3V @ 15A, +Vo2 = 1.8V @ 15A

zoom

DC610A

LT3804EFE LT3781EG LTC1693-1IS8 | Dual Output Isolated Power Supply, 36V to 72V Input, +Vo1 = 3.3V @ 15A, +Vo2 = 1.8V @ 15A

LT3804EFE LT3781EG LTC1693-1IS8 | Dual Output Isolated Power Supply, 36V to 72V Input, +Vo1 = 3.3V @ 15A, +Vo2 = 1.8V @ 15A

Product Detail

DC610A Demo Board for:

LTC1693 High Speed Single/Dual N-Channel MOSFET Drivers

LT3804 Secondary Side Dual Output Controller with Opto Driver

LT3781 Bootstrap Start Dual Transistor Synchronous Forward Controller

Tools & Simulations

Tools & Simulations 1

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.

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