The LT3575 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 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.