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ADI Power by Linear LT3575

Isolated Flyback Converter without an Opto-Coupler


TopologyOther Topology


The LT3575 is a monolithic switching regulator specifically designed for the isolated flyback topology. No third winding or optoisolator is required for regulation. The part senses the isolated output voltage directly from the primary side flyback waveform. A 2.5A, 60V NPN power switch is integrated along with all control logic into a 16-lead TSSOP package.

The LT3575 operates with input supply voltages from 3V to 40V, and can deliver output power up to 14W with no external power switch.The LT3575 utilizes boundary mode operation to provide a small magnetic solution with improved load regulation.

The output voltage is easily set with two external resistors and the transformer turns ratio. Off the shelf transformers are available for many applications.


  • 3V to 40V Input Voltage Range
  • 2.5A, 60V Integrated NPN Power Switch
  • Boundary Mode Operation
  • No Transformer Third Winding orOptoisolator Required for Regulation
  • Improved Primary-Side Winding Feedback Load Regulation
  • VOUT Set with Two External Resistors
  • BIAS Pin for Internal Bias Supply and Power NPN Driver
  • Programmable Soft-Start
  • Programmable Power Switch Current Limit
  • Thermally Enhanced 16-Lead TSSOP


  • See page num 11 for more inductor values.

Typical applications

  • Medical Isolated Power Supplies
  • Automotive
  • Industrial


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Flyback Transformer
Order Code Data­sheet
Order Code Data­sheet Downloads Product series Samples