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800V AC Switch for Smart Home Applications

STMicroelectronic’s new 3-Amp rms logic-level ac switch is now available in Fullpack and DPAK versions. Designed to drive most inductive loads in small motors, electric curtains, pumps, solenoids and water valves, ACST310 devices can be driven with only 10mA gate current allowing direct connection with an MCU by a simple resistor in series, avoiding the need for an external gate driver and making FMEA easier and reducing PCB size.

ST’s ACS Triacs, or ACSTs act as a Triacs, but with an enhanced voltage-transient clamping and absorbing capability. Both transients generated by load commutation and those coming from the mains line, such as those described in IEC 61000-4-5, are successfully absorbed by the device and the system. The clamping and crowbar function of the ACST ensure safe transient behavior for the system and the ACST. The circuit can thus be simplified, with no need for MOV or snubber circuits.

Drive loads subjected to high ac line spikes and transients with the logic-level ACST310, a 3A, 800V overvoltage-protected ac switch. Its high-voltage robustness and surge voltage capabilities prove its reliability in low-power appliance systems, and saves PCB space as any MOV protection or RC network can be removed. Available in two package versions, the ACST310-8B in DPAK and the ACST310-8FP in a 2kV UL1557-certified TO-220FPAB, it allows any standard microcontroller to drive resistive or inductive loads up to 250W.

This ACST310-8FP switch embeds a Triac structure and a high voltage clamping device able to absorb the inductive turn-off energy and withstand line transients such as those described in the IEC 61000-4-5 standard. The component needs a low gate current to be activated (IGT max. 10mA) and still shows a high electrical noise immunity complying with IEC standards such as IEC 61000-4-4 (fast transient burst test). It provides UL certified insulation rated at 2000Vrms.