APT1211SZ is a phototriac coupler in SOP4 package designed for AC line control applications with zero-cross detection capability. It features a repetitive peak OFF-state voltage rating of 600 V and an ON-state RMS current of 50 mA, with a maximum zero-cross voltage of 50 V at 10 mA LED current. The device provides 3,750 Vrms input-to-output isolation and operates reliably across an ambient temperature range of -40°C to +100°C. It is commonly used as a triac driver for solid-state relays (SSRs), heater controls in office equipment, home appliances, and industrial machinery, as well as for 100 V/200 V, 50/60 Hz line triac ignition applications.