LT3837 - Isolated No-Opto Synchronous Flyback Controller


  • Senses Output Voltage Directly from Primary Side Winding—No Optoisolator Required
  • Synchronous Driver for High Efficiency
  • Supply Voltage Range 4.5V to 20V
  • Accurate Regulation Without User Trims
  • Programmable Switching Frequency from 50kHz to 250kHz
  • Synchronizable
  • Load Compensation
  • Undervoltage Lockout
  • Available in a Thermally Enhanced 16-Lead TSSOP Package

Typical Application

LT3837 Typical Application
LT3837 Typical Application
LT3837 Typical Application


The LT3837 is an isolated switching regulator controller designed for medium power flyback topologies. A typical application is 10W to 60W with the part powered from a DC supply.

The LT3837 is a current mode controller that regulates an output voltage based on sensing the secondary voltage via a transformer winding during flyback. This allows for tight output regulation without the use of an optoisolator, improving dynamic response and reliability. Synchronous rectification increases converter efficiency and improves output cross regulation in multiple output converters.

The LT3837 operates in forced continuous conduction mode which improves cross regulation in multiple winding applications. Switching frequency is user programmable and can be externally synchronized. The part also has load compensation, undervoltage lockout and soft-start circuitry.

The LT3837 is available in a thermally enhanced 16-pin TSSOP package.


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
LT3837EFE#PBF TSSOP-16 FE E 05-08-1663 (BC) Yes
LT3837EFE#TRPBF TSSOP-16 FE E 05-08-1663 (BC) Yes
LT3837IFE#PBF TSSOP-16 FE I 05-08-1663 (BC) Yes
LT3837IFE#TRPBF TSSOP-16 FE I 05-08-1663 (BC) Yes

LT3837 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
LT3837EFE#PBF TSSOP-16 E $4.43 $3.10 Yes
LT3837EFE#TRPBF TSSOP-16 E $3.16 Yes
LT3837IFE#PBF TSSOP-16 I $4.69 $3.28 Yes
LT3837IFE#TRPBF TSSOP-16 I $3.34 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
DC1038A-A LT3837EFE | 9V -36V input to 3.3V at 10A Sync. Flyback Converter $225.00
DC1038A-B LT3837EFE | 9V -36V input to 5V at 7A Sync. Flyback Converter $200.00
DC1038A-C LT3837EFE | 9V -36V input to 12V at 3A Sync. Flyback Converter $175.00
DC950A-B LT3837EFE Demo Board | 9V ≤ Vin ≤ 36V, Vout: 5V/2A, 3.3V/3A, 2.5V/3A $150.00
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Click here to view our complete list of demo boards


  • Isolated Medium Power (10W to 60W) Supplies
  • Instrumentation Power Supplies
  • Isolated Medical Supplies

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