The AQY210KS is a solid-state relay in a miniature SOP4-pin package, designed with a latch-type short circuit protection feature. It is rated for a continuous load current of 120 mA and a load voltage of 350V (peak AC/DC). Key characteristics include a low maximum on-resistance of 35Ω, a low off-state leakage current of 1µA, and an I/O isolation voltage of 1,500V AC. The protection circuit activates when the output current exceeds a fixed amount, cutting off the current to protect downstream components until the input is reset. This relay is ideal for applications in modems, telephone equipment, measuring and testing equipment, and industrial controls.