Device identity and topology flexibility
The MIC38C43-1BM TR is a BiCMOS current-mode PWM controller from Microchip Technology, built to drive external power switches in isolated and non-isolated converter topologies. It supports Boost, Buck, Flyback, and Forward topologies, making it a single-part solution for a range of DC-DC converter architectures — useful when the same BOM line must serve multiple power stages.
Switching frequency and duty cycle limits
Switching frequency is rated at 500 kHz, which sets the transformer or inductor size floor — at this frequency a flyback transformer for a 10 W supply fits in an EFD15 core, keeping the PCB footprint compact. Maximum duty cycle reaches 96%, allowing the controller to maintain regulation with a very low input-to-output voltage differential — useful in a buck converter that must hold a 3.3 V rail from a 3.6 V input near the battery end-of-discharge.
Supply rails and start-up sequencing
Start-up threshold is 8.4 V, and the operating supply range (Vcc/Vdd) spans 7.6 V to 20 V. The 0.8 V hysteresis between start-up and the minimum operating voltage means the controller latches on cleanly once the auxiliary winding or bias rail comes up, without chattering at the threshold. The internal switch (rated for the application) and current-limiting fault protection are integrated, reducing external component count in the power stage.
Temperature grade and package fit
The 14-SOIC footprint is shared by many PWM controllers, easing second-source qualification without a PCB layout change.