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FAN4803CP1 View Datasheet(PDF) - Fairchild Semiconductor

Part Name
Description
View to exact match
FAN4803CP1
Fairchild
Fairchild Semiconductor Fairchild
FAN4803CP1 Datasheet PDF : 12 Pages
1 2 3 4 5 6 7 8 9 10 Next Last
PRODUCT SPECIFICATION
RCOMP =
1
2 × π × f × CCOMP
RCOMP =
6.2 8
1
× 30Hz
= 330k
× 16nF
1
CZERO
=
2
×
π
×
f
10
× RCOMP
CZERO
=
6.28
×
1
3Hz
×
=
330k
0.16 µF
FAN4803
Internal Voltage Ramp
The internal ramp current source is programmed by way of
(3) the VEAO pin voltage. Figure 7 displays the internal ramp
current vs. the VEAO voltage. This current source is used to
develop the internal ramp by charging the internal 30pF +12/
–10% capacitor. See Figures 10 and 11. The frequency of the
internal programming ramp is set internally to 67kHz.
PFC Current Sense Filtering
(4) In DCM, the input current wave shaping technique used by
the FAN4803 could cause the input current to run away.
In order for this technique to be able to operate properly
under DCM, the programming ramp must meet the boost
inductor current down-slope at zero amps. Assuming the
programming ramp is zero under light load, the OFF-time
will be terminated once the inductor current reaches zero.
VO
FAN4803
VEAO +
IOUT
220µF
11.3M
RLOAD
667
VEAO
330k
15nF
POWER
STAGE
0.15µF
COMPENSATION
FAN4803
IVEAO
34µA
Figure 4. Voltage Control Loop
0
Power Stage
Overall
Compensation
Network
50
100
150
200
0.1
1
10
100
FREQUENCY (Hz)
1000
Figure 6. Voltage Loop Phase
REV. 1.2.2 5/20/02
60
Power Stage
Overall Gain
40
Compensation
Network Gain
20
0
20
40
60
0.1
1
10
100
FREQUENCY (Hz)
1000
Figure 5. Voltage Loop Gain
50
FF @ 55ºC
40 TYP @ 55ºC
TYP @ ROOM TEMP
30 TYP @ 155ºC
SS @ 155ºC
20
10
0
0
1
2
3
4
5
6
7
VEAO (V)
Figure 7. Internal Ramp Current vs. VEAO
7
 

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