Functional check

AN2432

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Functional check

3.1

Start-up behavior at full load

Figure 11 and Figure 12 show the start-up phase at full output load at minimum and

maximum mains voltages. The rising time is nearly constant over all input voltage range.

The output voltage reaches its regulated value without any overshoot.

The soft-start function is integrated in the L6668 controller and can be programmed by

changing the value of C10.

3.2

Wake-up time

The wake-up time is the time needed for the output voltage to reach its nominal value from

the moment the adapter is plugged-in. Thanks to the internal high voltage start-up current

generator of the L6668, the wake-up time of this demo board is quite fast (approx. 900ms)

and, above all, independent of the mains voltage value.

When the IC starts, the generator is turned off, saving power in every working condition.

Figure 11.

Figure 12.

CH2: SS pin

CH3: Output voltage

CH2: SS pin

CH3: Output voltage