FAN4800 Datasheet, PDF (2/20 Pages) Fairchild Semiconductor – Low Start-Up Current PFC/PWM Controller Combos

Block Diagram
16
V_EAO
15 ^VFB
2.5V
0.3V
2 ^IAC
4 ^VRMS
3 ^ISENSE
RAMP1
7
GAIN
MODULATOR
1
I_EAO
Low Power
Detector
3.5k
POWER FACTOR CORRECTOR
V_CC
17.9V
V_CC OVP
2.78V
TRI-FAULT
PFC OVP
0.5V
-1V
3.5k
PFC CMP
PFC I_LIMIT
OSCILLATOR
13
V_CC
7.5V
REFERENCE
V_{REF 14}
SQ
R
SQ
R
PFC OUT
12
CLK
8 ^RAMP2
350
6 ^VDC
0.9V
V_CC
20μA
5 ^SS
350
V_REF
9 ^{DC ILIMIT}
PWM CMP
DUTY CYCLE
LIMIT
PWM DUTY
PFC
OUT
PWM
OUT
SS CMP
V_FB
2.25V
V_IN OK
1.0V
DC I_LIMIT
PULSE WIDTH MODULATOR
QS
R
SQ
R
PWM OUT
11
V_CC UVLO
GND
10
FAN4800 Rev.02
Figure 1. Internal Block Diagram
© 2005 Fairchild Semiconductor Corporation
FAN4800 Rev. 1.0.5
2
www.fairchildsemi.com