NCP1605, NCP1605A, NCP1605B
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29
Remarks:
The V
CONTROL
signal does not necessarily reach its
clamp level (3.7 V) depending of the load and of the system
time constants. In particular, if the circuit starts operation
in light load and if the bulk capacitor is not too large, the
output voltage V
OUT
generally exceeds the regulation level
while V
CONTROL
keeps below its upper limit.
The output voltage exhibits a 100 or 120 Hz ripple (at
twice the line frequency). This ripple is also present in the
V
CONTROL
voltage even if it is attenuated due to the
regulation low bandwidth. Like that of V
OUT
, this ripple is
not represented in Figure 70, for the sake of the clarity.
Figure 70. Startup Phase in Normal Conditions
V
CC
V
OUT
V
CONTROL
Flag1
Drive Output
pfcOK
Circuit State
OFF
V
CC
ON
V
CC
OFF
V
CC
STUP
V
OUT
Regulation Level
V
CONTROL
MAX = 3.7 V
These reactivations of Flag1 result from V
OUT
100 or 120 Hz ripple (not represented here for the
sake of clarity)
V
CC
INHIBIT