What are piezoresistors and thermistors? What is the difference?

Thermistor is a kind of sensitive element, which can be divided into positive temperature coefficient thermistor (PTC) and negative temperature coefficient (NTC) according to different temperature coefficients. The typical feature of thermistor is that it is sensitive to temperature and shows different resistance values at different temperatures. Positive temperature coefficient thermistor (PTC) has higher resistance at higher temperature, while negative temperature coefficient (NTC) has lower resistance at higher temperature, which belongs to semiconductor devices.

"Varistor" is a kind of resistance device with nonlinear volt-ampere characteristics, which is mainly used for voltage trap when the circuit is subjected to overvoltage and absorbing excessive current to protect sensitive devices. The English name is "Voltage Dependent Resistor", abbreviated as "VDR" or "Variety". The resistance material of varistor is semiconductor, so it is a semiconductor resistance. At present, "zinc oxide" (ZnO) varistors are widely used, and their main materials are 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 Province Province, China, varistor is called "surge absorber".

The symbol of 1. thermistor is PTC, and its resistance changes with the change of temperature, including positive temperature type and negative temperature type.

2. The resistance of the varistor changes with the change of voltage, and it can be divided into high, medium and low voltage varistors.

3. The common Nanjing Shi Heng thermistor is black in appearance and the varistor is blue. The words NTC or PTC 5d-9, 10d-9, 5d- 10D-9 are printed on the surface of the thermistor, and the words zov 10D 47 1k 65438+ are printed on the varistor.