Fairchild ML4824 Off-Line PFC-PWM Combo Controller Application Note

About this manual

This document is an application note for the Fairchild ML4824, a controller IC designed for off-line power factor correction (PFC) and pulse width modulation (PWM) cascade converters. It introduces a novel method using a leading/trailing edge modulation scheme to synchronize two cascaded power stages, thereby reducing output ripple voltage and simplifying loop compensation compared to traditional trailing edge modulation.

What's inside

• Introduction
• Cascade Power Converter
• Trailing Edge Modulation
• Leading Edge Modulation
• Output Voltage Ripple
• Synchronous Switching
• Experimental Results
• Application Circuit
• Block Diagram

Frequently asked questions

What is the input voltage range for the application circuit shown?

The application circuit is designed to accept an AC input voltage ranging from 80 to 264V.

What are the test conditions for the ML4824 versus ML4819 comparison?

The comparison was conducted with a 50pF capacitor, 220V AC input, 75W average power, 80kHz frequency, and 1.5mH inductance.

How much was the 120Hz output ripple voltage reduced in the 200W converter evaluation?

The evaluation showed that the 120Hz component of the output ripple voltage was reduced by 30%.