FEATURES

Provides Auxiliary Switch Activation

Complementary to Main Power

Switch Drive

Programmable deadtime (Turn-on

Delay) Between Activation of Each

Switch

Voltage Mode Control with

Feedforward Operation

Programmable Limits for Both

Transformer Volt- Second Product

and PWM Duty Cycle

High Current Gate Driver for Both

Main and Auxiliary Outputs

Multiple Protection Features with

Latched Shutdown and Soft Restart

Low Supply Current (100
A Startup,

1.5 mA Operation)

DESCRIPTION

The UCC3580 family of PWM controllers is designed to implement a variety

of active clamp/reset and synchronous rectifier switching converter topologies.

While containing all the necessary functions for fixed frequency, high

performance pulse width modulation, the additional feature of this design is

the inclusion of an auxiliary switch driver which complements the main

power switch, and with a programmable deadtime or delay between each

transition. The active clamp/reset technique allows operation of single

ended converters beyond 50% duty cycle while reducing voltage stresses

on the switches, and allows a greater flux swing for the power transformer.

This approach also allows a reduction in switching losses by recovering energy

stored in parasitic elements such as leakage inductance and switch

capacitance.

The oscillator is programmed with two resistors and a capacitor to set

switching frequency and maximum duty cycle. A separate synchronized

ramp provides a voltage feedforward pulse width modulation and a programmed

maximum volt-second limit. The generated clock from the oscillator

contains both frequency and maximum duty cycle information.