FAN4800 Datasheet, PDF (15/20 Pages) Fairchild Semiconductor – Low Start-Up Current PFC/PWM Controller Combos

L1
I1
+ _VIN
DC
SW2
I2
I3
I4
RL
C1
SW1
REF
U3
EA
OSC
RAMP
CLK
U4
VEAO
CMP
U1
DFF
R
Q
D _U2
Q
CLK
RAMP
VEAO
L1
I1
+ _VIN
DC
Figure 10. Typical Trailing-Edge Control Scheme
SW2
I2 I3
I4
RL
C1
SW1
RAMP
VEAO
U3
EA
REF
RAMP
OSC _CLK
U4
VEAO
CMP
U1
DFF
R
Q
D _U2
Q
CLK
Figure 11. Typical Leading-Edge Control Scheme
TIME
TIME
FAN4800 Rev.02
TIME
TIME
FAN4800 Rev.02
© 2005 Fairchild Semiconductor Corporation
FAN4800 Rev. 1.0.5
15
www.fairchildsemi.com