The difference between varistor and thermistor

　　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. The typical characteristic of thermistor is that it is sensitive to temperature, showing different resistance values at different temperatures. The positive temperature coefficient thermistor (PTC) has a larger resistance value when the temperature is higher, and the negative temperature coefficient thermistor (NTC) has a lower resistance value when the temperature is higher. They both belong to semiconductor devices.

　　A varistor is a resistive device with nonlinear volt-ampere characteristics, which is mainly used for voltage clamping when the circuit is subjected to overvoltage, absorbing excess current to protect sensitive devices. The English name is "VoltageDependentResistor" abbreviated as "VDR", or "Varistor". The resistance body material of the varistor is a semiconductor, so it is a variety of semiconductor resistors. Now widely used "zinc oxide" (ZnO) varistor, its main material is composed of divalent element zinc (Zn) and hexavalent element oxygen (O). So from the material point of view, zinc oxide varistor is a kind of "II-VI oxide semiconductor". In Taiwan, China, varistors are called "surge absorbers".

　　1. The thermistor symbol is PTC, the resistance value changes with the change of temperature, there are positive temperature type and negative temperature type.

　　2. The resistance value of the varistor varies with the voltage, high, medium and low voltage varistors.

　　3. The appearance of common thermistors is black, the varistor is blue, the surface of the thermistor is printed as NTC or PTC5D-9, 10D-9, 5D-13, etc., and the varistor is generally printed as ZOV10D471K14D561K, etc

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