Offline PWM controller for multi-topology supplies
The MIC38C44AYM is a current-mode PWM controller from Microchip Technology designed for offline switch-mode power supplies. It supports Boost, Buck, Flyback, and Forward topologies with an internal switch, making it a single-chip solution for isolated or non-isolated converters up to 500 kHz. The 50% maximum duty cycle limits the on-time per cycle — this is typical for current-mode controllers used in flyback and forward converters where transformer reset time must be guaranteed. The 14.5 V start-up threshold ensures the controller powers up cleanly from a bias winding or auxiliary supply.
Switching frequency and supply rail
Switching at 500 kHz allows the use of smaller magnetics and output capacitors compared to lower-frequency controllers, shrinking the overall power supply footprint. The 9 V to 20 V Vcc range covers standard bias rails from 12 V auxiliary windings down to 9 V regulated supplies. The 8-SOIC package (0.154" body width) is a common footprint for low-power offline controllers, with the exposed die pad providing a thermal path to the PCB copper.