The varistor is not sensitive to external pressure changes, and the resistor that is really sensitive to pressure should be a force sensitive resistor.
Force-sensitive resistor is a special component that converts mechanical force into electrical signal. It is made by using the pressure resistance effect of semiconductor materials, that is, the resistance value changes with the magnitude of external force. It is called pressure resistance abroad. Mainly used in various tension meters, torque meters, accelerometers, semiconductor microphones and various pressure sensors. Therefore, it is necessary to correctly distinguish between varistors and force-sensitive resistors.
A "varistor" is a resistive device with nonlinear volt-ampere characteristics. It is mainly used to clamp the voltage when the circuit is subjected to overvoltage and absorb excess current to protect sensitive devices. The English name is "Voltage Dependent Resistor" abbreviated as "VDR", or "Varistor". The resistor body material of a varistor is a semiconductor, so it is a variety of semiconductor resistors. Nowadays, the "zinc oxide" (ZnO) varistor is widely used, and its main material is composed of the divalent element zinc (Zn) and the hexavalent element oxygen (O). So from the point of view of materials, zinc oxide varistor is a kind of "II-VI group oxide semiconductor". In Taiwan, a varistor is called a "surge absorber", sometimes also called an "electric shock (surge) suppressor (absorber)".
Varistor is a voltage-limiting protection device. Utilizing the non-linear characteristics of the varistor, when an overvoltage occurs between the two poles of the varistor, the varistor can clamp the voltage to a relatively fixed voltage value, thereby realizing the protection of the subsequent circuit. The main parameters of varistor are: varistor voltage, current capacity, junction capacitance, response time, etc.
The response time of the varistor is ns, which is faster than the gas discharge tube and slightly slower than the TVS tube. Generally, the response speed of the over-voltage protection for electronic circuits can meet the requirements. The junction capacitance of a varistor is generally in the range of several hundred to several thousand Pf. In many cases, it is not suitable to be directly applied to the protection of high-frequency signal lines. When applied to the protection of AC circuits, because its large junction capacitance will increase leakage Current needs to be fully considered when designing the protection circuit. The current capacity of the varistor is larger, but smaller than that of the gas discharge tube. Varistor is abbreviated as VDR, which is a non-linear overvoltage protection semiconductor component sensitive to voltage.
（summarized by Easybom）
