The LT3573EMSE#PBF is an Isolated Flyback Converter without an opto-coupler 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. The LT3573 operates with input supply voltages from 3 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. It derives its information about the isolated output voltage by examining the primary-side flyback pulse waveform. Due to the sampling nature of the feedback loop, there are several timing signals and other constraints that are required for proper LT3573 operation.
1.25A, 60V Integrated NPN power switch
Boundary mode operation
No transformer third winding or opto-isolator required for regulation