The PC817X2CSP9F Photocoupler with Transistor Output Optocoupler manufactured by Sharp is a surface mount type optocoupler, which contains a light-emitting diode (LED) optically coupled to a photosensitive transistor in a 4-pin single-in-line package. The optocoupler isolates the low-voltage side from the high-voltage side and the LED and photosensitive element are held in close proximity in a molded plastic package. The package of the PC817X2CSP9F is a 4-pin single in line (SIP) package, with 8.2 mm wide body and a pitch of 0.6 mm, making it compact and suitable for applications with space constraints. The device has a high insulation resistance, good reliability, and an industry-standard pin configuration for easy replacement. It is suitable for use in Medical and home appliance circuits, telecom networks, and industrial applications.