转换模式 PFC 控制器
The and UCC38051 are PFC controllers for low-to-medium power applications requiring compliance with IEC 1000-3-2 harmonic reduction standard. The controllers are designed for a boost preregulator operating in transition mode also referred to as boundary-conduction mode or critical conduction-mode operation. They feature a transconductance voltage amplifier for feedback error processing, a simple multiplier for generating a current command proportional to the input voltage, a current-sense PWM comparator, PWM logic, and a totem-pole driver for driving an external FET.
In the transition mode operation, the PWM circuit is self-oscillating, with the turnon being governed by an inductor zero-current detector ZCD pin, and the turnoff being governed by the current-sense comparator. Additionally, the controller provides features such as peak current limit, default timer, overvoltage protection OVP and enable.