The Working Principle of Thermistor

Time : Feb 28 2015Source :analogtechnologies Author : Analog Click :
    Thermistor is one of thermal resistors, and the principle is that the resistance change is caused by the change of temperature. But now, the thermal resistor has generally been industrialized, which is basically refers to the PT100, CU50 and other commonly used thermal resistors. The difference between these two kinds of resistance: the thermal resistance is generally refers to the metal thermal resistance (PT100, etc); Thermistor is a semiconductor thermal resistance. The temperature coefficient of semiconductor thermal resistance is more than 10 to 100 times as big as that of metal, and it can detect the temperature change of 10~6℃ and select the resistance value of 0.1 ~ 100kΩ. That is why the semiconductor thermal resistance is called thermistor. The thermistor is generally used in circuit boards. It can be used as a protective device because the resistance changes with the change of temperature. Of course, this is only one aspect. There are many other uses of thermistor. For example, thermistor is used for the temperature compensation of the cold end. However, because of the obvious nonlinear relationship between the resistance and temperature, the consistency of the elements is very poor and it can not have a standard signal as the heat resistance does.
 NTC thermistor is the abbreviation of Coefficient Negative Temperature, which is the thermistor with negative temperature coefficient. It is made of the manganese, cobalt, nickel and copper and other metal oxide, which have the properties of the semiconductor. When the temperature is low, the number of oxide material carriers (electron and hole) will decrease, and its resistance value will go high; when the temperature becomes high, the number of carriers will increase, and the resistance will be low. At room temperature, NTC thermistor was varied in the range of 10~1000000Ω and the temperature coefficient is -2%~-6.5%. NTC thermistor can be widely used in temperature measurement, temperature compensation, surge current suppression and other occasions.