NCP1378 ON Semiconductor, NCP1378 Datasheet - Page 9

• Manufacturer Part Number: NCP1378
• Description: PWM Current-Mode Controller
• Manufacturer: ON Semiconductor

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4
Demagnetization Detection
voltage activity on the auxiliary winding. This voltage
further to the driver going−low transition. This prevents the
switching frequency to exceed (1.0/T
The core reset detection is done by monitoring the
An internal timer prevents any restart within 8.0 ms
−1.0
7.0
5.0
3.0
1.0
Figure 20. Core Reset Detection is Done through
RESTARTS
POSSIBLE
a Dedicated Auxiliary Winding Monitoring
Timeout
Timeout
Signal
Signal
Signal
Signal
Drain
Drain
0 V
Figure 19. When the primary natural ringing becomes too low, the current
sense initiates a new cycle when FB passes the skip level.
ON
+ 8.0 ms) but also
50 mV
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NCP1378
5 ms
9
Demag RESTART
Current Sense and Timeout Restart
features a FLYBACK polarity. The typical detection level
is fixed at 50 mV as exemplified by Figure 20.
avoid false leakage inductance tripping at turn−off. In some
cases, the leakage inductance kick is so energetic, that a
slight filtering is necessary.
COMPARATOR
TO INTERNAL
Figure 21. Internal Pad Implementation
ESD
5 ms
3
R
2 k
esd
4
ESD
1
4
1
5
R
dem
2
Aux