OPI110 and OPI1264 Series Optically Coupled Isolators The OPI110 and OPI1264 series of optoisolators consist of an 890 nm IR LED and a NPN phototransistor sensor. They are housed within an opaque package which has a transmissive path between the IR LED and the photosensor. Suitable applications for the OPI120 and OPI123 series include; high voltage isolation between input and output, electrical isolation, and industrial, medical and office equipment.