Thermistor is a resistor whose resistance value is very sensitive to temperature. It is also known as semiconductor thermistor. The main characteristics of thermistor is high sensitivity to temperature, small thermal inertia, long service life, small volume, simple structure, and various shapes, which has become the sensitive resistor used very widely.
There are many kinds of thermistor. According to the resistance temperature coefficient, it can be divided in two categories: positive temperature coefficient thermistor (PTC) and negative temperature coefficient thermistor (NTC); In terms of the resistance changes with temperature, there are slow variant (linear) and mutant (nonlinear); On the basis of the heating mode, it can be divided into direct heating and indirect heating; According to its operating temperature range, it can be classified into three categories: normal temperature (-55 to 315 ℃), low temperature (<-55 ℃) and high temperature (>315 ℃); According to the materials used, there are ceramic thermistor, semiconductor (crystal) thermal resistor, metal film thermistor, plastic thermistor, silicon carbide thermistor, glass state thermistor and so on. According to the structure, it can be divided into rod like, spherical, washer, discoid, bead, wire tubular, wafer, square sheet and thin film thermistor etc. The appearances of several thermistors are shown in the following pictures.
Power type thermistor (NTC) Temperature compensation type thermistor (NTC) Thermistor with electronic temperature meter (NTC)
Linear thermistor (PTC) Time delay starting thermistor (PTC) Overheating protection type thermistor (PTC)
