LT1725

PRODUCTION

General Purpose Isolated Flyback Controller

Part Models: 9
1ku List Price: Starting From $3.64

Viewing:

Overview

Drives External Power MOSFET with External I_SENSE Resistor
Application Input Voltage Limited Only by External Power Components
Senses Output Voltage Directly from Primary Side Winding—No Optoisolator Required
Accurate Regulation Without User Trims
Regulation Maintained Well into Discontinuous Mode
Switching Frequency from 50kHz to 250kHz with External Capacitor
Optional Load Compensation
Optional Undervoltage Lockout
Available in 16-Pin SO and SSOP Packages

The LT1725 is a monolithic switching regulator controller specifically designed for the isolated flyback topology. It drives the gate of an external MOSFET and is generally powered from a third transformer winding. These features allow for an application input voltage limited only by external power path components. The third transformer winding also provides output voltage feedback information, such that an optoisolator is not required. Its gate drive capability coupled with a suitable external MOSFET can deliver load power up to tens of watts.

The LT1725 has a number of features not found on most other switching regulator ICs. By utilizing current mode switching techniques, it provides excellent AC and DC line regulation. Its unique control circuitry can maintain regulation well into discontinuous mode in most applications. Optional load compensation circuitry allows for improved load regulation. An optional undervoltage lockout pin halts operation when the application input voltage is too low. An optional external capacitor implements a soft-start function. A 3V output is available at up to several mA for powering primary side application circuitry.

Applications

Telecom Isolated Converters
Offline Isolated Power Supplies
Instrumentation Power Supplies

Part Models: 9
1ku List Price: Starting From $3.64

Documentation

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 Model	Pin/Package Drawing	Documentation	CAD Symbols, Footprints, and 3D Models
LT1725CGN#PBF	16-Lead SSOP (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1725CGN#TRPBF	16-Lead SSOP (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1725CS#PBF	16-Lead SOIC (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1725CS#TRPBF	16-Lead SOIC (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1725IGN#PBF	16-Lead SSOP (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1725IGN#TRPBF	16-Lead SSOP (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1725IS	8-Lead SOIC (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1725IS#PBF	16-Lead SOIC (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1725IS#TRPBF	16-Lead SOIC (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys

Part Models	Product Lifecycle	PCN

Oct 3, 2024 - 24_0235 (QSOP/SSOP PKG) Migrating Bottom Trace Code Marking to Top Side Laser Marking
		PCN24_0235_Form Material_Report Other Delta Qualification Matrix
LT1725CGN#PBF	PRODUCTION
LT1725CGN#TRPBF	PRODUCTION
LT1725IGN#PBF	PRODUCTION
LT1725IGN#TRPBF	PRODUCTION
Oct 11, 2022 - 22_0235 Epoxy Change from Henkel 8290 to 8290A for GN Package
		PCN22_0235_Form Material_Report Qualification Results Summary Delta Qualification Matrix
LT1725CGN#PBF	PRODUCTION
LT1725CGN#TRPBF	PRODUCTION
LT1725IGN#PBF	PRODUCTION
LT1725IGN#TRPBF	PRODUCTION
Apr 6, 2022 - 22_0066 Laser Top Mark for 16QSOP Assembled in ADPG [PNG]
		PCN22_0066_Form Material_Report Delta Qualification Matrix
LT1725CGN#PBF	PRODUCTION
LT1725CGN#TRPBF	PRODUCTION
LT1725IGN#PBF	PRODUCTION
LT1725IGN#TRPBF	PRODUCTION
Oct 24, 2024 - 24_0246 Migrating Bottom Trace Code Marking to Top Side Laser Marking for SOIC_N Package
		PCN24_0246_Form Material_Report Marking Comparison Delta Qualification Matrix
LT1725CS#PBF	PRODUCTION
LT1725CS#TRPBF	PRODUCTION
LT1725IS	LAST TIME BUY
LT1725IS#PBF	PRODUCTION
LT1725IS#TRPBF	PRODUCTION
Oct 12, 2022 - 22_0252 Epoxy Change from Henkel 8290 to 8290A for 16-Lead SOIC Package
		PCN22_0252_Form Material_Report Qualification Results Summary
LT1725CS#PBF	PRODUCTION
LT1725CS#TRPBF	PRODUCTION
LT1725IS	LAST TIME BUY
LT1725IS#PBF	PRODUCTION
LT1725IS#TRPBF	PRODUCTION
Aug 6, 2022 - 22_0173 Laser Top Mark Conversion for SOICN14 and SOICN16 Packages Assembled on ADPG [PNG]
		PCN22_0173_Form Material_Report Delta Qualification Matrix
LT1725CS#PBF	PRODUCTION
LT1725CS#TRPBF	PRODUCTION
LT1725IS	LAST TIME BUY
LT1725IS#PBF	PRODUCTION
LT1725IS#TRPBF	PRODUCTION
May 29, 2025 - 25_0024 Carsem SnPb Packaging End of Life
		PDN25_0024_Form Material_Report
LT1725IS	LAST TIME BUY	PDN25_0024_Form Material_Report

This is the most up-to-date revision of the Data Sheet.

Software Resources

Can't find the software or driver you need?

Request a Driver/Software

Hardware Ecosystem

Parts	Product Life Cycle	Description
Switching Regulators & Controllers 2
LTM8047	RECOMMENDED FOR NEW DESIGNS	3.1V_IN to 32V_IN Isolated μModule (Power Module) DC/DC Converter
LTM8048	RECOMMENDED FOR NEW DESIGNS	3.1V_IN to 32V_IN Isolated μModule (Power Module) DC/DC Converter with LDO Post Regulator

Tools & Simulations

LTspice

Models for the following parts are available in LTspice:

LT1725

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.