How the thermistor works

　　Thermistor is a type of sensitive element, which is divided into positive temperature coefficient thermistor (PTC) and negative temperature coefficient thermistor (NTC) according to different temperature coefficients. A typical characteristic of thermistors is that they are sensitive to temperature and exhibit different resistance values at different temperatures.

　　working principle

　　The thermistor will be in an inactive state for a long time; when the ambient temperature and current are in zone c, the heat dissipation power of the thermistor is close to the heating power, so it may or may not operate. When the ambient temperature is the same, the operating time of the thermistor is shortened sharply with the increase of the current; when the ambient temperature is relatively high, the thermistor has a shorter operating time and a smaller holding current and operating current.

　　1. The ptc effect is that a material has a ptc (positive temperature coefficient) effect, that is, a positive temperature coefficient effect, which only means that the resistance of this material will increase with the increase of temperature. For example, most metal materials have ptc effect. In these materials, the ptc effect manifests as a linear increase in resistance with increasing temperature, which is commonly referred to as the linear ptc effect.

　　2. Non-linear ptc effect The phase-changed materials will show a phenomenon that the resistance increases sharply by several to ten orders of magnitude along a narrow temperature range, that is, the nonlinear ptc effect. Quite a variety of types of conductive polymers will exhibit this phenomenon. effect, such as polymer ptc thermistors. These conductive polymers are very useful for making overcurrent protection devices.

　　3. Polymer ptc thermistors are used for overcurrent protection. Polymer ptc thermistors are often called resettable fuses (hereinafter referred to as thermistors). Because of their unique positive temperature coefficient resistance characteristics, they are very suitable for Used as an overcurrent protection device. The use of the thermistor is the same as the ordinary fuse, which is used in series in the circuit.

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