ncp1377b ON Semiconductor, ncp1377b Datasheet - Page 9

• Manufacturer Part Number: ncp1377b
• Description: Pwm Current-mode Controller For Free-running Quasi-resonant Operation
• Manufacturer: ON Semiconductor

Demagnetization Detection
voltage activity on the auxiliary winding. This voltage
further to the driver going−low transition for NCP1377,
and 3.0 ms for NCP1377B. 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 21. Core Reset Detection is Done through
RESTARTS
POSSIBLE
a Dedicated Auxiliary Winding Monitoring
together with the sense comparator initiates a new cycle when FB passes the skip level.
Figure 20. When the primary natural ringing becomes too low, the internal TimeOut
Timeout
Timeout
Signal
Signal
Signal
Signal
Drain
Drain
0 V
ON
+ T
blank
) but also avoid false
50 mV
NCP1377, NCP1377B
http://onsemi.com
5 ms
9
Current Sense and Timeout Restart
Demag Restart
features a FLYBACK polarity. The typical detection level
is fixed at 50 mV as exemplified by Figure 21.
COMPARATOR
leakage inductance tripping at turn−off. In some cases, the
leakage inductance kick is so energetic, that a slight
filtering is necessary.
TO INTERNAL
R
esd
+ R
Figure 22. Internal Pad Implementation
int
R
int
= 28 k
5 ms
2
ESD2
R
esd
1
ESD1
1
4
5
R
dem
4
3
Aux