NCP1237 ONSEMI [ON Semiconductor], NCP1237 Datasheet - Page 12

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

shorted to GND (in case of V
pulldown on V
current is lowered when V
doesn’t turn on when V
HV pin is too low (below V
condition (TSD) has been detected. In all other conditions,
the HV current source always turns on and off to maintain
V
CC
HV stop
V
To reduce the power dissipation in case the V
There are only two conditions for which the current source
V
CC(min)
CC(on)
between V
DRV
V
CC
CC(min)
CC
to disable the controller), the startup
CC
and V
or AC OVP
Brown-out
detected
reaches V
CC
HV(min)
CC
CC(on)
is below V
Figure 6. Brown−out or Line Overvoltage Timing Diagram
capacitor failure, or external
), or a thermal shutdown
.
CC(min)
CC(inhibit)
: the voltage on
CC
.
http://onsemi.com
pin is
12
V
Brown−out and Line Overvoltage
brown−out condition is detected, and the controller stops.
The HV current source alternatively turns on and off to
maintain V
voltage is back above V
detected on the ac line, i.e. when the input voltage goes
above V
operation when the overvoltage condition has gone.
Waits next
CC(on)
When the input voltage goes below V
The same situation occurs when an overvoltage is
starting
before
HV(OV)
CC
between V
: the controller stops, and resumes normal
HV(start)
CC(on)
and V
.
CC(min)
until the input
HV(stop)
time
time
time
, a