AC line switch - basic application

ACS108-6S

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AC line switch - basic application

The ACS108-6S switch is triggered by a negative gate current flowing from the gate pin G.

The switch can be driven directly by the digital controller through a resistor as shown in

Figure 13.

Thanks to its overvoltage protection and turn-off commutation performance, the ACS108-6S

switch can drive a small power high inductive load with neither varistor nor additional turn-off

snubber.

Figure 13.

Typical application program

2.1

Protection against overvoltage: the best choice is ACS

In comparison with standard triacs, which are not robust against surge voltage, the ACS108-

in two operating conditions: in case of turn-off of very inductive load, and in case of surge

voltage that can occur on the electrical network.

2.1.1

High inductive load switch-off: turn-off overvoltage clamping

With high inductive and low RMS current loads the rate of decrease of the current is very

low. An overvoltage can occur when the gate current is removed and the OUT current is

As shown in Figure 14 and Figure 15, at the end of the last conduction half-cycle, the load

ACS turns off (3). The water valve, as an inductive load (up to 15 H), reacts as a current

generator and an overvoltage is created, which is clamped by the ACS (4). The current flows

through the ACS avalanche and decreases linearly to zero. During this time, the voltage

of the load is dissipated in the clamping section that is designed for this purpose. When the

energy has been dissipated, the ACS voltage falls back to the mains voltage value (5).

AC Mains

ACS108-6S

Valve

Power supply

MCU

Rg