The UCC28510 series of combination PFC/PWM controllers provide complete control functionality for any off-line power system requiring compliance with the IEC1000–3–2 harmonic reduction requirements. By combining the control and drive signals for the PFC and the PWM stages into a single device, significant performance and cost benefits are gained. By managing the modulation mechanisms of the two stages (leading-edge modulation for PFC and trailing-edge modulation for PWM), the ripple current in the boost capacitor is minimized.

Based on the average current mode control architecture with input voltage feedforward of prior PFC/PWM combination controllers, these devices offer performance advantages. Two new key PWM features are programmable maximum duty cycle and the 2x PWM frequency options to the base PFC frequency. For the PFC stage, the devices feature an improved multiplier and the use of a transconductance amplifier for enhanced transient response.

The core of the PFC section is in a three-input multiplier that generates the reference signal for the line current. The UCC28510 series features a highly linearized multiplier circuit capable of producing a low distortion reference for the line current over the full range of line and load conditions. A low-offset, high-bandwidth current error amplifier ensures that the actual inductor current (sensed through a resistor in the return path) follows the multiplier output command signal. The output voltage error is processed through a transconductance voltage amplifier.Read more