The 6N138 (F) is an optically isolated, self-biased, single channel photocoupler with a built-in Schmitt Trigger circuit designed by Toshiba. It is designed for interfacing between digital circuits and signals of long range such as AC/DC, A/D, D/A, and digital transducers. The optocoupler has a gallium arsenide infra-red LED emitter and a high speed silicon phototransistor detector. The device has a high common mode rejection ratio, so it is suitable for use in areas where voltage noise is high or with frequency changes. The typical switching time is 4µs, and the maximum collector-emitter voltage is 50V. The 6N138 (F) has a wide operating temperature range of -55°C to +110°C and a power dissipation rating of 200mW.