FAN4822

www.fairchildsemi.com FAN4822 ZVS Average Current PFC Controller Features Average current sensing, continuous boost, leading edge PFC for low total harmonic distortion and near unity power factor Built-in ZVS switch control with fast response for high efficiency at high power levels Average line voltage compensation with brownout control Current fed gain modulator improves noise immunity and provides universal input operation Overvoltage comparator eliminates output “runaway” due to load removal UVLO, current limit, and soft-start Precision 1.3% reference General Description The FAN4822 is a PFC controller designed specifically for high power applications. The controller contains all of the functions necessary to implement an average current boost PFC converter, along with a Zero Voltage Switch (ZVS) controller to reduce diode recovery and MOSFET turn-on losses. The average current boost PFC circuit provides high power factor (>98%) and low Total Harmonic Distortion (THD). Built-in safety features include undervoltage lockout, overvoltage protection, peak current limiting, and input voltage brownout protection. The ZVS control section drives an external ZVS MOSFET which, combined with a diode and inductor, soft switches the boost regulator. This technique reduces diode reverse recovery and MOSFET switching losses to reduce EMI and maximize efficiency. Block Diagram FB 14 2.5V IAC 4 VRMS 5 ISENSE 3 RTCT 6 VCCZ REF 13 REF + VEAO – + VEA 1 8 GND 2 IEAO OVP V...