This part is a kind of semiconductor called ACS108-6S.

Function of this product has Overvoltage protected AC switch.

Manufacturers : STMicroelectronics

Image and pinout :

Some of the text within the PDF file :

ACS108-6S Overvoltage protected AC switch (ACS™) Features ■ Needs no external protection snubber or varistor ■ Enables equipment to meet IEC 61000-4-5 ■ Reduces component count by up to 80% ■ Interfaces directly with the micro-controller ■ Common package tab connection supports connection of several alternating current switches (ACS) on the same cooling pad ■ Integrated structure based on A.S.D.® technology ■ Overvoltage protection by crowbar technology ■ High noise immunity - static dV/dt > 500 V/µs Applications ■ Alternating current on/off static switching in appliances and industrial control systems ■ Drive of low power high inductive or resistive loads like: – relay, valve, solenoid, – dispenser, door lock – pump, fan, low power motor Description The ACS [ ... ]

ACS108-6S PDF Datasheet Download