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Fault not confirmed
4.3V
3.0V
1.8V
fmax
0.9 V
Error flag
PFC off
DRV
Vcc
16.4V
11.2V
6.9V
Fb is ok
*This time is programmed by the Pin 6 capacitor. C
− Soft−Start Time (T
− Jittering Period (T
− Fault Detection Delay (T
More generally, the times approximately depend on C
− T
= 7.5 ms * C
ss
− T
jittering
− T
delay
Fault Management
100ms*
10ms* Jittering
fmin
PFC on
Fault occurs here
):7.5 ms
ss
): 10 ms
jittering
): 100 ms
delay
/ 390 nF
pin6
=10 ms * C
/ 390 nF
pin6
=100 ms * C
/ 390 nF
pin6
Figure 33. Fault Management
http://onsemi.com
NCP1239
Fault confirmed
100ms*
0.9 V
Error flag
= 390 nF nearly sets the following intervals:
pin6
as follows:
pin6
14
New Startup
attempt
OVL signal
(Over−Load)
0.9 V
Error flag
Reset at UVLO
PFC off
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