LTC3765 - Active Clamp Forward Controller and Gate Driver


  • Supports Self-Starting Secondary-Side Control
  • Direct Flux Limit™ Guarantees No Saturation
  • Active Clamp Drive with Delay Adjustment
  • On-Chip Bridge Rectifier Eliminates Need for Separate Gate Drive Bias Supply
  • Wide Input Supply Range: 8V and Up (Limited Only by External Components)
  • Linear Regulator Controller for Fast Start-Up
  • High Speed Gate Drivers
  • Precision UVLO with Adjustable Hysteresis
  • Overcurrent Protection
  • Overtemperature Protection
  • Adjustable Start-Up Frequency and Soft-Start
  • Tiny 16-Lead MSOP Package

Typical Application

LTC3765 Typical Application


The LTC®3765 is a start-up controller and gate driver for use in a self-starting secondary-side control forward converter. When combined with the LTC3766 secondary-side synchronous forward controller, a complete isolated power supply is created using a minimum of discrete parts. A proprietary scheme is used to multiplex gate drive signals and bias power across the isolation barrier through a small pulse transformer. The LTC3765 contains an onchip bridge rectifier that extracts gate drive bias power from this pulse transformer, eliminating the need for a separate bias supply. A precision undervoltage lockout circuit and linear regulator controller ensure a quick and well-controlled start-up.

The LTC3765 includes an active clamp output for driving an external PMOS, as well as an adjustable delay to optimize efficiency. The active clamp architecture reduces voltage stress on the main power switch, and provides the highest possible efficiency. Overcurrent protection and the Direct Flux Limit guarantee no transformer saturation without compromising transient response.


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
LTC3765EMSE#PBF MS-16E MSE E 05-08-1667 Yes
LTC3765EMSE#TRPBF MS-16E MSE E 05-08-1667 Yes
LTC3765HMSE#PBF MS-16E MSE H 05-08-1667 Yes
LTC3765HMSE#TRPBF MS-16E MSE H 05-08-1667 Yes
LTC3765IMSE#PBF MS-16E MSE I 05-08-1667 Yes
LTC3765IMSE#TRPBF MS-16E MSE I 05-08-1667 Yes
LTC3765MPMSE#PBF MS-16E MSE MP 05-08-1667 Yes
LTC3765MPMSE#TRPBF MS-16E MSE MP 05-08-1667 Yes

LTC3765 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
LTC3765EMSE#PBF MS-16E E $3.66 $2.56 Yes
LTC3765EMSE#TRPBF MS-16E E $2.62 Yes
LTC3765HMSE#PBF MS-16E H $4.50 $3.15 Yes
LTC3765HMSE#TRPBF MS-16E H $3.21 Yes
LTC3765IMSE#PBF MS-16E I $4.04 $2.83 Yes
LTC3765IMSE#TRPBF MS-16E I $2.89 Yes
LTC3765MPMSE#PBF MS-16E MP $11.03 $7.72 Yes
LTC3765MPMSE#TRPBF MS-16E MP $7.78 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
DC1739A-B LTC3765EMSE/LTC3766EGN Isolated Demo Board | Forward Converter, 18V ≤ VIN ≤ 72V; VOUT = 12V @ 12.5A $300.00
DC1739B-C LTC3765EMSE/LTC3766EGN Isolated Demo Board | Forward Converter, 9V ≤ VIN ≤ 36V; VOUT = 12V @ 10A $300.00
DC2199A-A LTC3765EMSE/LTC3766EGN Isolated Demo Board | Forward Converter, 36V ≤ VIN ≤ 60V; VOUT = 12V @ 30A $300.00
DC2199A-B LTC3765EMSE/LTC3766EGN Isolated Demo Board | Forward Converter with Sync Rectification, 36V ≤ VIN ≤ 60V; VOUT = 24V @ 15A $300.00
DC2199B-C LTC3765EMSE/LTC3766EGN Isolated Demo Board | Forward Converter with Sync Rectification, 36V ≤ VIN ≤ 60V; VOUT = 56V @ 5.4A $300.00
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Click here to view our complete list of demo boards


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