Datasheet

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Output Capacitor
2 2
2
OUT HOLDUP
OUT (min)
OUT OUT _ HOLDUP(min)
P t
C
V V
³
-
2 2
2 350 21 28
240
390 300
OUT (min)
W . ms
C F
V V
m
´ ´
³ ³
-
0 05
OUT _ RIPPLE( pp ) OUT
V . V<
0 05 390 19 5
OUT _ RIPPLE( pp ) PP
V . V . V< ´ <
2
OUT
OUT _ RIPPLE( pp )
LINE(min) OUT
I
V
( f )Cp
=
0 9
11 26
2 47 270
OUT _ RIPPLE( pp )
. A
V . V
( Hz ) Fp m
= =
´ ´
2
2
OUT (max)
Cout _ fline
I
I =
2
0 9
0 635
2
Cout _ fline
. A
I . A= =
16
1 5
3
OUT
Cout _ HF OUT (max)
IN _ RECTIFIED(min)
V
I I .
Vp
= -
16 390
0 9 1 5 1 8
3 120
Cout _ HF
V
I . A . . A
Vp
´
= - =
´
2 2
2Cout _ RMS( total ) Cout _ fline Cout _ HF
I I I= +
2 2
0 635 1 8 1 9
Cout _ RMS( total )
I . A . A . A= + =
UCC28019
SLUS755B – APRIL 2007 – REVISED DECEMBER 2007
The output capacitor, C
OUT
, is sized to meet holdup requirements of the converter. Assuming the downstream
converters require the output of the PFC stage to never fall below 300 V, V
OUT_HOLDUP(min)
, during one line cycle,
t
HOLDUP
= 1/f
LINE(min)
, the minimum calculated value for the capacitor is:
It is advisable to de-rate this capacitor value by 20%; the actual capacitor used is 270 µ F.
Setting the maximum peak-to-peak output ripple voltage to be less than 5% of the output voltage will ensure that
the ripple voltage will not trigger the output over-voltage or output under-voltage protection features of the
controller. The maximum peak-to-peak ripple voltage, occurring at twice the line frequency, and the ripple current
of the output capacitor are calculated:
The required ripple current rating at twice the line frequency is equal to:
There will also be a high frequency ripple current through the output capacitor:
The total ripple current in the output capacitor is the combination of both and the output capacitor must be
selected accordingly:
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Product Folder Link(s): UCC28019