ncp1239f ON Semiconductor, ncp1239f Datasheet - Page 20

• Manufacturer Part Number: ncp1239f
• Description: Lowstandby High Performance Pwm Controller
• Manufacturer: ON Semiconductor

Timer
Vcc
PWM
PFC
Vcc
0.9V
flag
7.5ms*
SS
regulation
*This time is programmed by the Pin 6 capacitor. C
More generally, the times approximately depend on C
100ms*
− Soft−Start Time (T
− Jittering Period (T
− Fault Detection Delay (T
− T
− T
− T
ss
jittering
delay
= 7.5 ms * C
=100 ms * C
16.4V
6.9V
11.2V
=10 ms * C
Stby stby is left
Standby
is confirmed
pin6
jittering
ss
pin6
100ms*
pin6
):7.5 ms
/ 390 nF
/ 390 nF
/ 390 nF
): 10 ms
delay
): 100 ms
http://onsemi.com
Nom
Pout
Figure 38.
NCP1239
Short−circuit
100ms*
20
pin6
pin6
= 390 nF nearly sets the following intervals:
as follows:
One Vcc cycle is skipped to
lower the burst mode duty
cycle to typically 5% in
fault conditions.
If the fault had disappeared
the SMPS would recover
normal operation
100ms*
Short−circuit