An optically coupled device

摘要

An optically coupled device (PK) is composed of input and output sides. The input side includes a light-emitting element (10) while the output side includes: an element for driving (11); a light-receiving element (12) for receiving light from the light-emitting element to turn on the element for driving; and a resistance element (13) having a positive or negative temperature-coefficient and connected in series with the light-receiving element (12). By the above configuration, the optically coupled device by itself is constructed to prevent rush-current from occurring and protect the device itself from being excessively heated due to excessive current.