DESCRIPTION
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.

FEATURES
■ 3V to0 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

APPLICATIONS
■ Industrial, Automotive and Medical Isolated Power Supplies