The characteristics and functions of the thermistor

A thermistor is a type of sensitive component that has the characteristics of a sensitive component and is a sensor that converts a change in temperature into an electrical signal. Thermistors include positive temperature coefficient (PTC) and negative temperature coefficient (NTC) thermistors, as well as critical temperature thermistors (CTR).

A thermistor is usually a non-linear resistor made of a semiconductor ceramic material that is extremely sensitive to temperature and has a very low thermal inertia, and its resistance changes with temperature. The thermistor is divided into three categories according to the temperature coefficient: negative temperature coefficient (NTC), positive temperature coefficient (PTC) and critical temperature coefficient. The resistance of the positive temperature coefficient resistor increases with the increase of temperature, the resistance of the negative temperature coefficient resistor decreases with the increase of temperature, and the resistance of the critical temperature coefficient resistor is substantially zero near the critical temperature.

Most of the thermistors are direct-heat type, that is, the heat source is obtained by the heat generated by the resistor itself when passing current. There is also a side-heating type that requires an external heating source. Common thermistors are round, washer-shaped, tubular, etc. The most widely used is the negative temperature coefficient thermistor (NTC), which can be divided into temperature measurement type, voltage regulation type and common type. There are many types and shapes, and common ones are tubular, round, and the like.

Positive temperature coefficient sensitive resistors (PTCs) are used in a wider range of applications. In addition to temperature control and temperature measurement circuits, they are also widely used in degaussing circuits for color TVs, refrigerators, electric mosquito repellents, electric irons, etc. In the household appliance circuit.