Main uses of NTC thermistors

　　1. Temperature sensor and nonlinear correction

　　NTC thermistor is a kind of temperature sensor which is widely used in the field of industrial temperature measurement. Compared with semiconductor integrated temperature sensors, NTC thermistors have the characteristics of wide temperature measurement range, convenient use and low price; compared with platinum thermal resistance or thermocouple, NTC thermistor has the advantages of high sensitivity, simple circuit and low price. Features.

　　The temperature measurement range of the thermistor can reach -100℃~500℃, and its sensitivity can reach -44000ppm/℃ (at 25℃). The resistance depends on its semiconductor material, size, shape, and the contact area of the electrodes, with a thick and narrow thermistor having a relatively high resistance, while a thin and wide shape has a lower resistance.

　　Since it is used as a temperature sensor, generally better linearity is required. However, there is an exponential relationship between the resistance value of the thermistor and the temperature. In a large temperature range, the relationship between the resistance value and temperature has a relatively serious nonlinearity. At this time, the nonlinear correction will achieve better results.

　　2. Anti-surge protection

　　Another very extensive use of NTC thermistors is the anti-surge current protection of the power supply. In the rectifier and filter circuit, in order to avoid the instantaneous surge current caused by the capacitive load charging when the electronic circuit is turned on, it is usually used in the power supply circuit. A power NTC thermistor is connected in series. This can effectively reduce the inrush current at startup, and after the inrush current reduction is completed, due to the continuous action of the passing current, the resistance of the NTC thermistor will drop to a very small value, and the power consumption is very small and can be ignored. , will not affect the normal operation of the circuit. Therefore, in small and medium power power supply circuits, the method of using power NTC thermistors to reduce the inrush current at startup is widely used.

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