NCP1246 ONSEMI [ON Semiconductor], NCP1246 Datasheet - Page 32

• Manufacturer Part Number: NCP1246
• Description: Fixed Frequency Current Mode Controller for Flyback Converters
• Manufacturer: ONSEMI [ON Semiconductor]

Overcurrent Protection with Fault timer
sensing signal, making it able to work with any transformer,
even with very poor coupling or high leakage inductance.
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
latched off (latched protection, option A) or this latch can be
released in autorecovery mode (option B), the controller
tries to restart after t
The overload protection depends only on the current
When an overcurrent occurs on the output of the power
autorec
fault
. Other possibilities of the latch
timer is started: once the timer
Figure 67. Overpower Compensation Timing Diagram
ILIM
. When this
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NCP1246
32
release are the brownïout condition or the V
reset. The timer is reset when the CS setpoint goes back
below V
started if the driver signal is reset by the maximum on time.
The controller also enters the same protection mode if the
voltage on the CS pin reaches 1.5 times the maximum
internal setpoint V
shortïcircuits) or there appears low V
Figures 68 and 69 for the timing diagram.
resumes operation; if not, the system starts a new burst cycle.
In autorecovery mode if the fault has gone, the supply
ILIM
before the timer elapses. The fault timer is also
CS(stop)
(allows to detect winding
CC
CC
supply. See
power on