NCP1234 ONSEMI [ON Semiconductor], NCP1234 Datasheet - Page 23

• Manufacturer Part Number: NCP1234
• Description: Fixed Frequency Current Mode Controller for Flyback Converters
• Manufacturer: ONSEMI [ON Semiconductor]

Overcurrent protection with Fault timer
supply, the FB loop asks for more power than the controller
can deliver, and the CS setpoint reaches V
event occurs, an internal t
times out, DRV pulses are stopped and the controller is either
When an overcurrent occurs on the output of the power
FB
CS
blanking
t
fault
/ 5
LEB
timer is started: once the timer
+
Figure 40. Timer−Based Overcurrent Protection
V
ILIM
+
+
−
−
PWM
ILIMIT
. When this
R
S
Q
http://onsemi.com
timer
23
t
fault
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
To provide maximum output power at the low input line
voltages the fault timer is not started if the driver signal is
reset by the max duty cycle.
Reset
Protection
Mode
release
timer
t autorec
Autorecovery
ILIM
mode only
protection
before the timer elapses.
Reset DRV