PC814 Optocoupler IC

PC814 Photocoupler IC has a transistor that is controlled based on light (photon). So this IC basically has a pair of two IR (infrared) LEDs connected in reverse polarity and a photo-transistor inside it. When the IR LED is powered the light from it falls on the transistor and it conducts. PC814 IC is used to provide electrical isolation between two circuits, one of which is connected to IR LEDs and the other to a phototransistor. The digital signal sent to the IR LED is reflected on the transistor, but there is no physical connection between the two. This IC can be used to detect AC switching.

This comes in handy when you're trying to isolate a noisy signal from your digital electronics, so if you're looking for an IC to provide optical isolation in your circuit design, this could be the one.