The UCC2891/2/3/4 family of PWM controllers is designed to simplify implementation of the various active clamp/reset switching power topologies. The UCC289x is a peak current-mode, fixed-frequency, high-performance pulse width modulator. It includes the logic and the drive capability for the auxiliary switch with a simple method of programming the critical delays for proper active clamp operation. The UCC2891/3 includes a 110-V start-up regulator for initial start-up and to provide keep-alive power during stand-by. Additional features include an internal programmable slope compensation circuit, precise DMAX limit, and a single resistor programmable synchronizable oscillator.
The UCC2891 is a peak‑current‑mode PWM controller designed for active‑clamp and reset‑forward flyback converters. It includes a 110‑V start‑up regulator, programmable dead‑time, slope compensation and a synchronizable oscillator, enabling high‑efficiency, low‑EMI power supplies up to 700 W.
The document provides absolute maximum ratings, recommended operating conditions, ordering information, package thermal resistance, pin assignments, electrical characteristics, functional block diagram, terminal functions and detailed pin descriptions for the D, PW, SOIC‑16 and TSSOP‑16 packages.
| Line input voltage range | 120 V |
|---|---|
| Supply voltage range | 15 V |
| Maximum duty cycle | 73 % |
| Output source current (peak) | 2 A |
| Operating junction temperature range | -40 °C to 105 °C |
The controller includes a 110‑V input start‑up regulator.
The recommended operating junction temperature is –40 °C to 105 °C.
The output can source up to 2 A peak current.
The device is offered in D and PW taped‑and‑reeled packages, as well as SOIC‑16 and TSSOP‑16 variants.