ML4827
TYPICAL PERFORMANCE CHARACTERISTICS
250
250
TRANSCONDUCTANCE (µ )
TRANSCONDUCTANCE (µ )
200
200
Ω
Voltage Error Amplifier (VEA) Transconductance (g
m
)
400
VARIABLE GAIN BLOCK CONSTANT - K
Ω
150
100
50
0
0
1
2
VFB (V)
3
4
5
300
200
100
0
0
1
2
3
VRMS (mV)
16
VEAO
VFB
15
2.5V
IAC
2
VRMS
4
ISENSE
3
RAMP 1
7
OSCILLATOR
GAIN
MODULATOR
3.5kΩ
VEA
–
+
–
+
–
150
100
50
0
–500
0
IEA INPUT VOLTAGE (mV)
500
Current Error Amplifier (IEA) Transconductance (g
m
)
4
5
Gain Modulator Transfer Characteristic (K)
1
IEAO
IEA
+
POWER FACTOR CORRECTOR
BROKEN WIRE
COMPARATOR
2.7V
+
–
2µA
VREF
OVP
VCCZ
13.5V
VCC
13
VREF
3.5kΩ
+
7.5V
REFERENCE
14
1V
–
S
–1V
+
–
Q
Q
PFC OUT
Q
Q
12
R
S
R
PFC ILIMIT
Figure 1. PFC Section Block Diagram.
6