Specifications: The APY453S is a Normally Closed (1 Form B) PhotoMOS solid-state relay in a compact SOP-4 surface-mount package. It is rated for a load current of 150mA and a load voltage of 250V (AC/DC). It features an on-state resistance of 9Ω, provides 2500Vrms isolation between the input and output, and operates over a wide temperature range of -40°C to 85°C. The control input requires 1.2-1.4VDC, with switching times of 300μs (turn-on, which opens the circuit) and 100μs (turn-off, which closes it).

Application Scenarios: Designed for fail-safe applications where the load must be energized by default. Ideal for use in safety interlock systems, emergency stop (E-stop) circuits, alarm monitoring systems, and watchdog timer outputs in industrial automation, medical equipment, and automotive control units where a guaranteed default "on" state is critical for safety or functionality.