NCP1236
Overcurrent protection with Fault timer
When an overcurrent occurs on the output of the power
supply, the FB loop asks for more power than the controller
latched off (latched protection, version A), or it enters an
autorecovery mode (version B). The timer is reset when the
CS setpoint goes back below V
before the timer elapses.
ILIM
can deliver, and the CS setpoint reaches V
. When this
The fault timer is also started if the driver signal is reset by
the max duty cycle.
ILIMIT
event occurs, an internal t
timer is started: once the timer
fault
elapsed, DRV pulses are stopped and the controller is either
Fault Flag
PWM
/ 5
+
FB
−
timer
R
Q
S
Protection
Mode
Reset DRV
t
fault
release
Autorecovery
protection
mode only
blanking
timer
t autorec
+
−
CS
t
LEB
Brown−out
+
Reset
VILIM
DC MAX
DRV
Figure 44. Timer−Based Overcurrent Protection
In autorecovery mode, the controller tries to restart after
. If the fault has gone, the supply resumes operation;
t
autorec
if not, the system starts a new burst cycle.
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