LT3573 - Isolated Flyback Converter without an Opto-Coupler

The LT®3573 is a monolithic switching regulator specifically designed for the isolated flyback topology. No third winding or opto-isolator is required for regulation. The part senses the isolated output voltage directly from the primary-side flyback waveform. A 1.25A, 60V NPN power switch is integrated along with all control logic into a 16‑lead MSOP package.

The LT3573 operates with input supply voltages from 3V to 40V, and can deliver output power up to 7W with no external power devices.The LT3573 utilizes boundary mode operation to provide a small magnetic solution with improved load regulation.

Features
  • 3V to 40V Input Voltage Range
  • 1.25A, 60V Integrated NPN Power Switch
  • Boundary Mode Operation
  • No Transformer Third Winding or Opto-Isolator 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 MSOP
Typical Application

Applications
  • Industrial, Automotive and Medical Isolated Power Supplies
Packaging
Order Information
Part NumberPackageTempPrice(1-99)Price (1k)*
LT3573EMSE#PBFMS-16EE$3.95$2.76
LT3573EMSE#TRPBFMS-16EE$2.82
LT3573IMSE#PBFMS-16EI$4.46$3.12
LT3573IMSE#TRPBFMS-16EI$3.18
Demo Boards
Part NumberDescriptionPrice
DC1228ALT3573EMSE | 10V to 30VIN, 5Vout at 1A Isolated Monolithic Flyback Converter$100.00
Datasheet
Design Note
Reliability Data
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