3 Cross Regulation and Standby

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peak current defined by the disable level applied at to pin #9. This functionality is well visible in

Figure 11., where the most significant waveforms are depicted during the standby operation. It

is possible to check that the circuit stops switching as soon as the COMP pin voltage is equal to

the SKIPADJ voltage and restarts to operate as soon as the threshold returns at the same level

with the mentioned voltage histeresys. In the above table also the auxiliary voltage

measurement is shown. At minimum load the value is still enough to ensure correct operation

of the L6668 with margin. During standby operation the output voltages are only affected by a

slight ripple at burst frequency, due to the operation of the internal control comparator. The

ripple peak to peak measured in worst case at 265Vac on the 5V output was 68mV.

Figure 10. Pin at 230vac vs. Iout 5V

Figure 11. Vin = 230 Vrms - 50Hz

Pin @230vac vs. Iout 5V

0

0.2

0.4

0.6

0.8

1

1.2

1.4

20

30

40

50

60

70

80

Iout 5V [mA]