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.
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)