NCP1395 データシートの表示（PDF） - ON Semiconductor

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NCP1395

High Performance Resonant Mode Controller

ON Semiconductor 

NCP1395A/B

1 ires1 2 vout

20.0

10.0

0

−10.0

−20.0

SS Action

1

Ires

Figure 42. Soft−Start Behavior

177

Target is

175

reached

173

2

Vout

171

169

200u

600u

1.00m

time in seconds

1.40m

1.80m

Figure 43. A Typical Startup Sequence on an LLC

Converter

Please note that the soft−start will be activated in the

following conditions:

• A startup sequence

• During auto−recovery burst mode

• A brown−out recovery

• A temperature shutdown recovery

The fast fault input undergoes a special treatment. Since

we want to implement skip cycle through the fast fault

input on the NCP1395A, 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 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 13. 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.

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