Temperature Sensor with 2-Wire Interface

When designing a precision outdoor temperature sensor it is a good idea to electrically isolate the sensor from the signal conditioning circuitry to protect it from voltage spikes such as might be induced by lightning. Digital signal transmission is preferred over analogue as the circuitry is more straightforward, communication is more reliable and subsequent processing of the temperature readings is easier. In the present design the signal and the power for the converter circuit are both carried on just two wires.