The AQY410SX is a PhotoMOS solid-state relay featuring a normally-closed Form B output configuration designed for AC/DC dual-use applications. It is housed in a compact SOP4-pin package measuring 4.3 × 4.4 × 2.1 mm and is rated for a maximum load voltage of 350V (peak AC) with a continuous load current of 120mA. The device exhibits low on-resistance of 26O typical (35O maximum) and an extremely low off-state leakage current of 1µA maximum, making it ideal for controlling low-level analog signals. With an operating temperature range of -40°C to +85°C and I/O isolation voltage of 1,500Vrms, the AQY410SX is well-suited for power supplies, measuring instruments, security equipment, telephone systems, and sensing applications where reliable switching and signal isolation are required.