Linear Technology's LT3748 is a switching regulator controller specifically designed for the isolated flyback topology and capable of high power. It drives a low side external N-channel power MOSFET from an internally regulated 7 V supply. No third winding or opto-isolator is required for regulation, as the part senses the isolated output voltage directly from the primary-side flyback waveform.

The LT3748 utilizes boundary mode to provide a small magnetic solution without compromising load regulation. Operating frequency is set by load current and transformer magnetizing inductance. The gate drive of the LT3748, combined with a suitable external MOSFET, allow it to deliver load power up to several tens of watts from input voltages as high as 100 V.