thermistor

thermistorIt is a sensor resistor whose resistance value changes with temperature. According to different temperature coefficients, it is divided into positive temperature coefficient resistors (PTC thermistors) and negative temperature coefficient resistors (NTC thermistors). The resistance value of a positive temperature coefficient resistor increases with the increase of temperature, while the resistance value of a negative temperature coefficient resistor decreases with the increase of temperature. Both belong to semiconductor devices.

Principle:

Will remain inactive for a long time; When the ambient temperature and current are in zone C, the heat dissipation power of the thermal resistor 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 decreases sharply with the increase of current; Thermistors have shorter operating time and smaller holding and operating currents when the ambient temperature is relatively high.

1. The PTC effect is a material that exhibits a positive temperature coefficient (PTC) effect, meaning that the resistance of the material increases with temperature. Most metal materials have PTC effect. In these materials, the PTC effect is manifested as a linear increase in resistance with increasing temperature, which is commonly referred to as the linear PTC effect.

2. The nonlinear PTC effect refers to the phenomenon in which materials undergoing phase transition exhibit a sharp increase in resistance along a narrow temperature range of several to more than ten orders of magnitude, known as the nonlinear PTC effect. A considerable number of types of conductive polymers exhibit this effect, such as polymer PTC thermistors. These conductive polymers are very useful for manufacturing overcurrent protection devices.

3. Polymer PTC thermistor is used for overcurrent protection, and polymer PTC thermistor is often referred to as self recovering fuse (referred to as thermistor). Due to its positive temperature coefficient resistance characteristics, it is extremely suitable for use as an overcurrent protection device. The use of thermal resistors is similar to that of ordinary fuses, which are connected in series in a circuit.

thermistor Features:

① High sensitivity, its temperature coefficient of resistance is more than 10-100 times larger than that of metals, and it can detect temperature changes of 10-6 ℃;

② The working temperature range is wide, with normal temperature devices suitable for temperatures between -55 ℃ and 315 ℃, high-temperature devices suitable for temperatures above 315 ℃ (currently up to 2000 ℃), and low-temperature devices suitable for temperatures between -273 ℃ and -55 ℃;

③ Small in size, capable of measuring the temperature of gaps, cavities, and blood vessels in the body that cannot be measured by other thermometers;

④ Easy to use, the resistance value can be freely selected between 0.1 and 100k Ω;

⑤ Easy to process into complex shapes and capable of mass production;

⑥ Good stability and strong overload capacity.