A typical characteristic of thermistors is temperature sensitivity, which shows different resistance values at different temperatures. When the temperature is high, the resistance value of the positive temperature coefficient (PTC) thermistor is high, while when the temperature is high, the resistance value of the negative temperature coefficient (NTC) thermistor is low.

With the continuous development of measurement and control technology, the system level design puts forward higher requirements for the thermistor measurement circuit, which requires not only the measurement accuracy and stability, but also the fault diagnosis. Thermistor temperature measurement circuit needs to detect open thermistor circuit fault or open circuit fault.

The temperature measuring circuit of thermistor is usually realized by the principle of DC or unbalanced bridge source. The thermistor temperature measuring circuit based on the principle of DC source has the advantages of low temperature and flexible interface. The circuit interface can realize the temperature measurement circuits of two-wire, three wire and four wire thermistors through simple changes. The principle of DC source is a relatively easy to realize high-precision thermistor temperature measurement system.

The structural characteristics of the fault detection circuit of thermistor temperature measurement circuit are that it includes detection resistance, a / D converter and processing unit. The detection resistor is connected in series on the return line of the DC source thermistor temperature measurement circuit, the A / D converter is connected to both ends of the detection resistor, and the processing unit is connected to the A / D converter.