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ACST310-8B

Application information

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2.2

AC line transient voltage ruggedness

In comparison with standard Triacs, which are not robust against surge voltage, the

level against fast transients. The ACST310 switch can safely withstand AC line transient

voltages either by clamping the low energy spikes, such as inductive spikes at switch off, or

by switching to the on state (for less than 10 ms) to dissipate higher energy shocks through

the load. This safety feature works even with high turn-on current ramp up.

The test circuit of Figure 17 represents the ACST310 application, and is used to stress the

ACST310 switch according to the IEC 61000-4-5 standard conditions. With the additional

effect of the load which is limiting the current, the ACST310 switch withstands the voltage

spikes up to 2 kV on top of the peak line voltage. The protection is based on an overvoltage

crowbar technology. The ACST310 folds back safely to the on state as shown in Figure 18.

The ACST310 recovers its blocking voltage capability after the surge and the next zero

current crossing. Such a non-repetitive test can be done at least 10 times on each AC line

voltage polarity.

Figure 17. Overvoltage ruggedness test circuit for resistive and inductive loads for

IEC 61000-4-5 standards