www.fairchildsemi.com

REV. 1.0.1 8/10/01

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) con-

troller 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, over-

voltage 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 recov-

ery and MOSFET switching losses to reduce EMI and maxi-

mize efficiency.

Block Diagram

Q

S

R

–

+

1

14

VEAO

VEA

2.5V

FB

4

5

+

–

3

8

GND

2

IEAO

+

–

IEA

R+

R–

+

–

–

–

6

OSC

GAIN

MODULATOR

S

R

Q

+

–

2.7V

FB

–1V

12

13.5V

ZVS OUT

11

Q

S

R

Q

PFC OUT

9

PWR GND

10

OVP

I LIMIT

REF

13

ZV SENSE

7

+

REF

Q

FAN4822

ZVS Average Current PFC Controller