This part is a kind of semiconductor called ACS108-5SN.

Function of this product has AC LINE SWITCH.

Manufacturers : STMicroelectronics

Image and pinout :

Some of the text within the PDF file :

® ASD™ AC Switch Family ACS108-5Sx AC LINE SWITCH MAIN APPLICATIONS ■ AC on-off static switching in appliance & industrial control systems ■ Drive of low power high inductive or resistive loads like - relay, valve, solenoid, dispenser - pump, fan, micro-motor - defrost heater FEATURES ■ Blocking voltage: VDRM / VRRM = 500V ■ Clamping voltage: VCL = 600V ■ Nominal current: IT(RMS) = 0.8 A ■ Gate triggering current : IGT < 10mA ■ Triggering current is sourced by the gate ■ Switch integrated driver ■ Drive reference COM connected to the SOT-223 tab BENEFITS ■ Needs no external overvoltage protection. ■ Enables the equipment to meet IEC61000-4-5 standard. ■ Allows straightforward connection of several SOT-223 devices on the same cooling pad. �� [ ... ]

ACS108-5SN PDF Datasheet Download