Specifications: The APY274AE is the through-hole DIP-4 version of a medium-voltage PhotoMOS SSR. It is a 1 Form A (SPST-NO) relay rated for 350mA load current and 400V load voltage (AC/DC). It has an 8Ω on-state resistance, provides 5000Vrms isolation, and switches with 500μs (turn-on) and a fast 30μs (turn-off) time. It operates from -40°C to 85℃ with a 1.0-1.4VDC input range. Application Scenarios: A compact through-hole relay for safe and reliable switching at several hundred volts. Common applications include industrial sensor and transducer power isolation, medical device auxiliary control, power supply output enable/disable, driving other solid-state relays, and as an isolation component in test and measurement equipment for medium-voltage circuits, offering a good balance of size, voltage rating, and isolation strength.