New power AC switches feature built-in surge protection

SINGAPORE: Two new families of AC power switches from STMicroelectronics simplify the design of domestic appliances and industrial equipment by integrating surge protection that meets the international standard IEC 61000-4-5, which is usually implemented using external components.

The 10A ACST10 and 12A ACST12 families complete ST’s range for applications from 2A to 12A. They can be used for protecting washing-machine motors, compressors for refrigerators or air-conditioning units, or in industrial drives.

The devices replace conventional electromechanical relays or TRIAC-based power switches, which require additional external components to prevent damage caused by voltage surges in the AC supply or by energy stored in the load.

Several other external components can also be eliminated since the switch input can be connected directly to the appliance’s electronic control unit, whereas a relay or TRIAC typically requires a separate input driver. In addition, designers must usually add components to prevent unpredictable turn-on or turn-off of the motor, but these, also, are not required when using the ACST10 or ACST12.

Package options include the industry-standard through-hole TO-220AB and plastic insulated TO-220FPAB packages for the ACST10 family, and TO-220AB or surface-mount D2PAK for the ACST12 family. The devices are in production now at prices from $0.51 for ACST10 devices and $0.61 for the ACST12 family, for orders over 10,000 units.