ML4822 Datasheet, PDF (1/10 Pages) Micro Linear Corporation – ZVS Average Current PFC Controller

May 1997
ML4822*
ZVS Average Current PFC Controller
GENERAL DESCRIPTION
The ML4822 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.
FEATURES
s Average current sensing, continuous boost, leading
edge PFC for low total harmonic distortion and near
unity power factor
s Built-in ZVS switch control with fast response for high
efficiency at high power levels
s Average line voltage compensation with brownout
control
s Current fed gain modulator improves noise immunity
and provides universal input operation
s Overvoltage comparator eliminates output “runaway”
due to load removal
s UVLO, current limit, and soft-start
s Precision 1% reference
*This Part Is End Of Life As Of August 1, 2000
BLOCK DIAGRAM (Pin configuration shown for 14-pin package)
FB
14
1
VEAO
– ^VEA
8
GND
2.5V
+
R+
IAC
4
VRMS
5
ISENSE
3
GAIN
MODULATOR
R–
IEA
+
–
2
IEAO
+
–
RTCT
6
REF
13
VCCZ
REF
OSC
ZV SENSE
+
7
––
FB
2.7V
OVP
+
–
I LIMIT
–1V +
–
VCCZ
13.5V
VCC
12
SQ
R
SQ
RQ
SQ
RQ
PFC OUT
11
ZVS OUT
10
PWR GND
9
1