DocID3572 Rev 4

9/17

AN390

AVS description

17

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power on reset of the IC and if a low line voltage is sensed. If the AC line voltage

changes from typically 110 V to 230 V, then the AVS circuit turns the Triac off. If the AC

line voltage changes back from 230 V to 110 V, the AVS IC controller waits 8 mains

cycles before to turn the Triac on (see Figure 6). This is done to check if the AC line

voltage is a stable 110 V value and that the voltage reduction is not a short voltage dip.

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means that if the device is turned into a bridge mode, it will remain in the bridge mode,

even if the AC line voltage suddenly dips into the 110 V range (see Figure 7).

VAC (NOMINAL RMS)

Vthres2

Tdelay

< 1 AC line cycle

8 AC line cycles

< 1 AC line cycle

IG

time

time

Triac OFF

Triac ON

Triac OFF

Triac ON

Triac OFF

Vthres1

100V

240V

Tdelay

< 1 AC line cycle

IG

time

Triac OFF

Triac ON

Triac OFF

VAC (NOMINAL RMS)

Vthres2

time

Vthres1

240V

100V