LT1725 - General Purpose Isolated Flyback Controller
- Drives External Power MOSFET with External ISENSE 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
AEC-Q100 data available for specific packages
DescriptionThe 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.
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 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
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Demo BoardsLinear 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.
|DC373A-A||LT1725IGN | 48Vin to 5Vout 2A Module, Isolated Flyback, 1x2 Footprint||$150.00|
|DC373A-B||LT1725IGN | 48Vin to 3.3V/3A, 10W Module, Isolated Flyback, 1x2 Footprint||$150.00|
|DC431A||LT1725CGN LTC1773EMS | Telecom Input, Isolated 3 Output DC/DC Converter, +36V to +72V Input, Vout = 5V/1A, 3.3V/5A, 2.5V/4A||Contact Factory|
|DC508A||LT1725CGN | Low Cost, High Efficiency Synchronous Forward Converter w/o Optoisolator, +Vin = 36V-72V, +Vout = 2.5V/3.3V at 10A||Contact Factory|
|DC562A-A||LT1725CGN | Isolated Forward Converter, Vin=36V to 72V, Vout=3.3V@30A||Contact Factory|
|DC562A-B||LT1725CGN | Isolated Forward Converter, Vin=36V to 72V, Vout=5V@20A||Contact Factory|
|DC562A-C||LT1725CGN | Isolated Forward Converter, Vin=36V to 72V, Vout=12V@12A||Contact Factory|
|DC638A||LT1725CGN | Synchronous Flyback Converter, 36V - 72Vin, to 3.3V @ 3.5A, 350mA Input Current||Contact Factory|
Designed for Automotive and Transportation ApplicationsAEC-Q100 data is available for these specific part numbers. Please contact your local sales representative for more information regarding reliability reports or to inquire about parts that are not included. For more information, view our Automotive and Transportation page
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- Telecom Isolated Converters
- Offline Isolated Power Supplies
- Instrumentation Power Supplies
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