The LED and sensor are in hermetically sealed packages that are then mounted in a high dielectric plastic housing. This device is designed for applications that require data transmission and high voltage isolation between the input and output of up to 50,000 volts. The output of the OPI155 is an NPN transistor with the emitter grounded while providing TTL type output levels. A typical pull-up resistor of 10 K (10,000) ohms would provide a very good output signal with a minimum sink current for the device of 15 mA. The input of the OPI155 is an IR-LED and can be driven using a standard TTL gate. Input currents are in the 15 to 20 mA range.