Description 

The UCC3895 is a phase-shift PWM controller that implements control of a full-bridge power stage by phase shifting the switching of one half-bridge with respect to the other. The device allows constant frequency pulse-width modulation in conjunction with resonant zero-voltage switching to provide high efficiency at high frequencies. The part is used either as a voltage-mode or current-mode controller. While the UCC3895 maintains the functionality of the UC3875/6/7/8 family and UC3879, it improves on that controller family with additional features such as enhanced control logic, adaptive delay set, and shutdown capability. Because the device is built using the BCDMOS process, it operates with dramatically less supply current than it’s bipolar counterparts. The UCC3895 operates with a maximum clock frequency of 1 MHz.

Features

• Programmable-output turnon delay

• Adaptive delay set

• Bidirectional oscillator synchronization

• Voltage-mode, peak current-mode, or average

current-mode control

• Programmable soft start, soft stop, and chip

disable via a single pin

• 0% to 100% duty-cycle control

• 7-MHz error amplifier

• Operation to 1 MHz

• Typical 5-mA operating current at 500 kHz

• Very low 150-μA current during UVLO

Applications

• Phase-shifted full-bridge converters

• Off-line, telecom, datacom, and servers

• Distributed power architecture

• High-density power modules