The AQY410SZ is a normally closed (1-Form-B) PhotoMOS relay designed for AC/DC dual use in a compact SOP4-pin package. It is rated for a 350V load voltage and a 120mA continuous load current. Key electrical characteristics include a typical on-resistance of 18 Ω, a low maximum off-state leakage current of 1 μA, and an I/O isolation voltage of 1,500 Vrms. Its ability to control low-level analog signals without distortion makes it suitable for various applications, including measuring instruments, security equipment, and power supplies.