FAN4822 Datasheet, PDF (1/10 Pages) Fairchild Semiconductor – ZVS Average Current PFC Controller

FAN4822
ZVS Average Current PFC Controller
www.fairchildsemi.com
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
FB
14
1
VEAO
– ^VEA
8
GND
2.5V +
R+
I_AC
4
V_RMS
5
I_SENSE
3
GAIN
MODULATOR
R–
IEA
+
–
2
IEAO
+
–
R_TC_T
6
REF
13
V_CCZ
REF
OSC
ZV SENSE
+
7
––
FB
2.7V
OVP
+
–
I LIMIT
–1V +
–
V_CCZ
13.5V
V_CC
12
SQ
R
SQ
RQ
SQ
RQ
PFC OUT
11
ZVS OUT
10
PWR GND
9
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