www.fairchildsemi.com
FAN4822
ZVS Average Current PFC Controller
Features
General Description
• 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
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
VEAO
FB
–
14
2.5V
IAC
4
+
1
8
2
GND
FB
R+
+
GAIN
MODULATOR
+
VCC
OVP
12
VCCZ
13.5V
IEA
2.7V
–
+
–
–
VRMS
5
IEAO
VEA
S
Q
I LIMIT
R–
–1V
ISENSE
+
R
–
3
PFC OUT
11
RTCT
6
OSC
S
Q
R
Q
VCCZ
REF
13
ZV SENSE
7
ZVS OUT
REF
10
+
–
–
S
Q
R
Q
PWR GND
9
REV. 1.0.1 8/10/01
PRODUCT SPECIFICATION
FAN4822
Operating Conditions
Temperature Range
Min.
Max.
Units
FAN4822IX
–40
85
°C
Electrical Characteristics
Unless otherwise specified, RT = 52.3kΩ, CT = 470pF, TA = Operating Temperature Range (Note 1)
Parameter
Conditions
Min.
Typ.
Max.
Units
7
V
Voltage Error Amplifier
Transconductance
0
50
70
120
µ
Feedback Reference Voltage VEAO = VFB
2.4
2.5
2.6
V
Open Loop Gain
60
75
dB
60
75
dB
PSRR
VNON-INV = VINV, VEAO = 3.75V
Ω
Input Voltage Range
VCCZ – 3V < VCC < VCCZ – 0.5V
Output Low
0.65
Output High
1
V
6.0
6.7
V
Source Current
∆VIN = ±0.5V, VOUT = 6V
–40
–80
µA
Sink Current
∆VIN = ±0.5V, VOUT = 1.5V
40
80
mA
Current Error Amplifier
Transconductance
–1.5
VNON-INV = VINV, IEAO = 3.75V
130
V
Open Loop Gain
195
310
µ
±3
Input Offset Voltage
PSRR
2
Ω
Input Voltage Range
±15
mV
60
VCCZ – 3V < VCC < VCCZ – 0.5V
75
dB
60
75
dB
Output Low
0.65
Output High
1
V
6.0
6.7
V
Source Current
∆VIN = ±0.5V, VOUT = 6V
–30
–80
µA
Sink Current
∆VIN = ±0.5V, VOUT = 1.5V
40
80
µA
Threshold Voltage
2.6
2.7
2.8
V
Hysteresis
80
120
150
mV
–0.8
–1.0
–1.15
V
150
300
ns
50
ns
7.5
7.65
V
OVP Comparator
ISENSE Comparator
Threshold Voltage
Delay to Output
ZV Sense Comparator
Propagation Delay
Threshold Voltage
Input Capacitance
REV. 1.0.1 8/10/01
100mV Overdrive
7.35
6
pF
3
