NCP1237 ONSEMI [ON Semiconductor], NCP1237 Datasheet - Page 13

• Manufacturer Part Number: NCP1237
• Description: Fixed Frequency Current Mode Controller for Flyback Converters
• Manufacturer: ONSEMI [ON Semiconductor]

can start immediately. When it crosses V
time the controller must not stop instantaneously when the
input voltage goes above V
V
V
HV(start)
HV(stop)
When V
The same scheme is used for the Line OVP, except that this
DRV
V
HV
HV
crosses the V
Starts at next
HV(start)
V
CC(ON)
HV(OV1)
threshold, the controller
Figure 7. AC Input Brown−out Timing Diagram
. In order to be
HV(stop)
, it triggers
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13
a timer of duration t
doesn’t stop in case of line cycle drop−out.
insensitive to spikes and voltage surges a blanking circuit is
inserted after the output of the comparator, with a duration
of t
OV(blank)
.
t
HV
Brown-out
HV
: this ensures that the controller
time
time