This application note presents a practical power factor corrected design for a 500 Watt output and universal mains input application. The detailed derivations of all power, IC biasing and control component values and types will be shown. The evaluation results from an actual working demoboard will be presented as well as several relevant oscillograms.
This document presents a practical, low-cost design for a 500 Watt output power supply with universal mains input (88Vac to 264Vac). It details the implementation of an active power factor correction circuit using the L4981A Continuous Mode IC to meet regulatory requirements for line current harmonics and power factor.
| Output Power | 500W |
|---|---|
| Input Voltage Range | 88Vac to 264Vac |
| Output Voltage | 400Vdc |
| Switching Frequency | 80kHz |
| Input Power Factor | > 0.99 |
| THD | < 5% |
The design employs the L4981A Continuous Mode PFC IC.
The maximum output overvoltage is set to 450V.
The selected power MOSFET is the STW20NA50.