LTC3725 - Single-Switch Forward Controller and Gate Driver

Features

  • High Speed Gate Driver for Forward Converter
  • On-Chip Rectifier and Self-Starting Architecture Eliminates Need for Separate Gate Drive Bias Supply
  • Wide Input Voltage Supply Range: 9V and Up
  • Linear Regulator Controller for Fast Start-Up
  • Precision UVLO with Adjustable Hysteresis
  • Overcurrent Protection
  • Volt-Second Limit Prevents Transformer Core Saturation
  • Voltage Feedforward for Fast Transient Response
  • Available in 10-Lead MSOP Package

Typical Application

LTC3725 Typical Application

Description

The LTC3725 is a controller for a single-switch forward converter and includes an on-chip gate driver.

For secondary-side control, combine the LTC3725 with the LTC3706 PolyPhase secondary-side synchronous forward controller to create a complete forward converter using a minimum of discrete parts. A proprietary scheme is used to multiplex gate drive signals across the isolation barrier through a tiny pulse transformer. The on-chip rectifier and the same pulse transformer provide gate drive bias power.

Alternatively, the LTC3725 can be used as a standalone voltage mode controller in a primary-side control architecture with optoisolator feedback. Voltage feedforward provides excellent line regulation and transient response.

Packaging

CAD Symbols and Footprints: The downloadable Zip file below contains the schematic symbol and PCB footprints.

For complete and up to date package information and drawings, please refer to our packaging page

Part Number Package Code Temp Package
Drawing
RoHS
LTC3725EMSE#PBF MS-10E MSE E 05-08-1664 Yes
LTC3725EMSE#TRPBF MS-10E MSE E 05-08-1664 Yes
LTC3725IMSE#PBF MS-10E MSE I 05-08-1664 Yes
LTC3725IMSE#TRPBF MS-10E MSE I 05-08-1664 Yes


LTC3725 Package Drawing

Order Info

  • Part numbers ending in PBF are lead free. Solder plated terminal finish (SnPb) versions are non-standard and special terms and conditions and pricing applies if available. Please contact LTC marketing for information.
  • Part numbers containing TR or TRM are shipped in tape and reel or 500 unit mini tape and reel, respectively
  • Please refer to our general ordering information or the product datasheet for more details

Package Variations and Pricing

Part Number Package Temp Price
(1-99)
Price
(1k)*
RoHS
LTC3725EMSE#PBF MS-10E E $3.66 $2.56 Yes
LTC3725EMSE#TRPBF MS-10E E $2.62 Yes
LTC3725IMSE#PBF MS-10E I $4.04 $2.83 Yes
LTC3725IMSE#TRPBF MS-10E I $2.89 Yes
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* The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Linear Technology sales office or authorized distributor.

Demo Boards

Linear Technology offers many demo boards free of charge to qualified customers. Contact your local sales office or distributor to inquire about a demo board. Certain demo boards are also available for sale via credit card on this website. Demo boards are for evaluation purposes only. It remains the customer’s responsibility to verify proper and reliable operation in the actual end application.

Part Number Description Price Documentation
DC1031A-A LTC3725EMSE/LTC3726EGN Demo Board | Single-Switch Forward Converter, 36V ≤ VIN ≤ 72V, Vout = 2.5V @ 20A $250.00
DC1031A-B LTC3725EMSE/LTC3726EGN Demo Board | Single-Switch Forward Converter, 36V ≤ VIN ≤ 72V, Vout = 3.3V @ 20A $250.00
DC1031A-C LTC3725EMSE/LTC3726EGN Demo Board | Single-Switch Forward Converter, 36V ≤ VIN ≤ 72V, Vout = 5V @ 20A $250.00
DC1032A LTC3725EMSE/LTC3726EGN 1/8 Brick | 36V < Vin < 72V, Vout: 12V/10A $250.00
DC1174A-A LTC3725EMSE/LTC3726EGN 1/8 Brick | 9V < Vin < 36V, Vout: 5.0V/10A $200.00
DC1174A-B LTC3725EMSE/LTC3726EGN 1/8 Brick | 9V < Vin < 36V, Vout: 12V/4A $200.00
DC1174A-C LTC3725EMSE/LTC3726EGN 1/8 Brick | 9V < Vin < 36V, Vout: 15V/3A $200.00
DC1300A-A LTC3725EMSE/LTC3726EGN 1/4 Brick | 9V < Vin < 36V, Vout: 5.0V/20A $200.00
DC1300A-B LTC3725EMSE/LTC3726EGN 1/4 Brick | 9V < Vin < 36V, Vout: 12V/8.4A $200.00
DC1300A-C LTC3725EMSE/LTC3726EGN 1/4 Brick | 9V < Vin < 36V, Vout: 15V/6.7A $200.00
DC888A-A LTC3725EMSE/LTC3706EGN Demo Board | 1/4 Brick, 36V ≤ Vin ≤ 72V, Vout: 3.3V/50A Contact Factory
DC888A-B LTC3725EMSE/LTC3706EGN Demo Board | 1/4 Brick, 36V ≤ Vin ≤ 72V, Vout: 5V/40A Contact Factory
DC888A-C LTC3725EMSE/LTC3706EGN Demo Board | 1/4 Brick, 36V ≤ Vin ≤ 72V, Vout: 12V/20A Contact Factory
Buy Now
Click here to view our complete list of demo boards

Applications

  • Isolated 48V Telecommunication Systems
  • Internet Servers and Routers
  • Distributed Power Step-Down Converters
  • Automotive and Heavy Equipment

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Design Tools

LTspice

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Models for the following parts are available in LTspice:
LTC3725

Technical Support