Flyback controller for isolated offline supplies
The Texas Instruments UCC28780RTET is an offline flyback controller designed for isolated AC-DC power supplies. It operates without an internal switch, relying on an external MOSFET to handle the power stage. Switching frequency reaches up to 1 MHz, which lets the transformer shrink — a 1 MHz flyback can use a smaller core than a 65 kHz design, saving board space in compact adapters or auxiliary supplies. The supply range spans 12 V to 34 V on the Vcc pin, and the start-up threshold is 17.5 V — typical for a bias winding that comes up after the bulk cap charges through the start-up resistor.
Protection set and temperature grade
Built-in fault protection covers overcurrent, overtemperature, overvoltage, and short circuit — the controller latches off or retries depending on the fault, so a downstream MOSFET sees less stress during a hard short on the secondary.
Active production and compliance
No pin-compatible second source is documented from TI or another vendor; the BOM line is single-sourced to this order code.