NCP1396B ON Semiconductor, NCP1396B Datasheet - Page 18

• Manufacturer Part Number: NCP1396B
• Description: High Performance Resonant Mode Controller featuring High-voltage Drivers
• Manufacturer: ON Semiconductor

Please note that the soft-start will be activated in the
following conditions:
−
−
−
−
The fast fault input undergoes a special treatment. Since
we want to implement skip cycle through the fast fault
input on the NCP1396A, we cannot activate the soft−start
every time the feedback pin stops the operations in low
power mode. Therefore, when the fast fault pin is
Brown-Out protection
protect the resonant converter from low DC input
voltages. Below a given level, the controller blocks the
output pulses, above it, it authorizes them. The internal
A startup sequence
During auto−recovery burst mode
A brown−out recovery
A temperature shutdown recovery
-4.00
-8.00
The Brown-Out circuitry (BO) offers a way to
4.00
3.00
2.00
1.00
16.0
12.0
8.00
4.00
8.00
4.00
0
0
0
56.2u
A – B
Clock pulses
Ct voltage
DT
Figure 42. Typical oscillator waveforms
65.9u
NCP1396A, NCP1396B
http://onsemi.com
18
ti
i
75.7u
released, no soft−start occurs to offer the best skip cycle
behavior. However, it is very possible to combine skip
cycle and true fast fault input, e.g. via ORing diodes
driving pin 6. In that case, if a signal maintains the fast
fault input high long enough to bring the feedback level
down (that is to say below 0.6 V) since the output voltage
starts to fall down, then the soft−start is activated after the
release of the pin. In the B version tailored to operate
from an auxiliary 12 V power supply, the soft−start is
always activated upon the fast fault input release,
whatever the feedback condition is.
circuitry, depicted by figure 43, offers a way to observe
the high-voltage (HV) rail. A resistive divider made of
Rupper and Rlower, brings a portion of the HV rail on pin
5. Below the turn-on level, the 27µA current source IBO
is off. Therefore, the turn-on level solely depends on the
division ratio brought by the resistive divider.
DT
d
DT
85.4u
95.1u