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.