Photocouplers are required to have a package shape and dielectric strength based on safety standards. When designing in accordance with safety standards, you need to check the following items.
Creepage distance of isolation
The shortest distance along the surface of the insulator between two conductors (primary and secondary).
The shortest distance between two conductors measured through air.
The minimum distance of insulator between two conductors
Isolation voltage between two conductors *
In the case of UL, the AC voltage that does not break the insulation even if it is applied for 1 minute is specified.
* Products with isolation voltage ranging from 2,500 Vrms to 5,000 Vrms are mainstream.