1. Products
  2. Power Management
  3. Switching Regulators
  4. Flyback, Forward, and Isolated Controller
  5. LT3825


Features and Benefits

  • Senses Output Voltage Directly from Primary Side Winding—No Opto-Isolator Required
  • Synchronous Driver for High Efficiency
  • Input Voltage Limited Only by External Power Components
  • Accurate Output Regulation without User Trims
  • Switching Frequency from 50kHz to 250kHz
  • Synchronizable
  • Load Compensation
  • Programmable Undervoltage Lockout
  • Available in a Thermally Enhanced 16-Lead TSSOP Package

Product Details

The LT3825 is an isolated switching regulator controller designed for medium power flyback topologies. A typical application is 10W to 60W with input voltage limited only by external power path components. A third transformer winding provides output voltage feedback.

The LT3825 is a current mode controller that regulates output voltage based on sensing secondary voltage via a transformer winding during flyback. This allows for tight output regulation without the use of an opto-isolator, improving dynamic response and reliability. Synchronous rectification increases converter efficiency and improves output cross regulation in multiple output converters.

The LT3825 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 circuity.


  • Isolated Medium Power (10W to 60W) Supplies
  • Isolated Telecom, Medical Converters
  • Instrumentation Power Supplies
  • Isolated Power over Ethernet Supplies

Product Lifecycle icon-recommended Production

At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.

Evaluation Kits (6)

Tools & Simulations


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.

To launch ready-to-run LTspice demonstration circuits for this part:

Step 1: Download and install LTspice on your computer.

Step 2: Click on the link in the section below to download a demonstration circuit.

Step 3: If LTspice does not automatically open after clicking the link below, you can instead run the simulation by right clicking on the link and selecting “Save Target As.” After saving the file to your computer, start LTspice and open the demonstration circuit by selecting ‘Open’ from the ‘File’ menu.


Models for the following parts are available in LTspice:


Product Recommendations

LT3825 Companion Parts

Recommended µModule Regulator

Recommended Suggested Oscillator

Design Resources

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 Number Material Declaration Reliability Data Pin/Package Drawing CAD Symbols, Footprints & 3D Models
LT3825EFE#PBF Material Declaration Reliability Data 16-Lead TSSOP w/ EP
LT3825EFE#TRPBF Material Declaration Reliability Data 16-Lead TSSOP w/ EP
Wafer Fabrication Data R458 Reliability Data

PCN-PDN Information

Select a model from the dropdown below to subscribe to PCN/PDN notifications and view past notifications as well.

Sample & Buy

Ordering FAQs

See our Ordering FAQs for answers to questions about online orders, payment options and more.


Buy Now Pricing

(**) Displayed Buy Now Price and Price Range is based on small quantity orders.


List Pricing

(*)The 1Ku 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 Analog Devices, Inc. authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.


Lead Times

Please see the latest communication from our CCO regarding lead times.



Selecting the Sample button above will redirect to the third-party ADI Sample Site. The part selected will carry over to your cart on this site once logged in. Please create a new account there if you have never used the site before. Contact SampleSupport@analog.com with any questions regarding this Sample Site.

Price Table Help


Evaluation Boards

Pricing displayed is based on 1-piece.

Up to two boards can be purchased through Analog.com. To order more than two, please purchase through one of our listed distributors.

Pricing displayed is based on 1-piece. The USA list pricing shown is for budgetary use only, shown in United States dollars (FOB USA per unit), and is subject to change. International prices may vary due to local duties, taxes, fees and exchange rates.