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    Principle and application of NTC thermistor.Smart PIR Sensor Factory

    source:Industry News release time:2022-06-25 Hits:     Popular:Infrared sensing module

      

      NTC is called a negative temperature coefficient thermistor. It is prepared from a ceramic material that is fully mixed with Mn-Co-Ni oxides and then sintered. While achieving miniaturization, it also has resistance value-temperature characteristic fluctuations. The characteristics of small size and fast response to various temperature changes can be used as high-sensitivity and high-precision temperature sensors, and are often used in electronic circuits for real-time temperature monitoring and temperature compensation. As the temperature of the body increases, the resistance value of NTC will decrease nonlinearly, which is the characteristic of NTC. In order to make better use of this feature, we need to clearly understand the basic parameters of NTC before application, which will be discussed in this article, hoping to help electronic R&D engineers in actual circuit design.

      R25: Resistance value of NTC body at 25℃

      B value: material constant, which is a parameter used to express the range of resistance of NTC with temperature in the working temperature range, which is related to the composition of the material and the sintering process. In addition, the B value of NTC will be affected by temperature changes, so we usually select two temperature points on the curve to calculate. When expressing the B value, the selected temperature point should be marked, such as B25/85. The larger the B value, the faster the resistance decreases with the increase of temperature, and the opposite is the case when the B value is smaller.

      ɑ value: The so-called temperature coefficient of resistance (α) refers to the zero-load resistance change rate when the temperature changes by 1°C at any temperature. The relationship between the temperature coefficient of resistance (α) and the B value can be expressed by the following formula:

      The minus sign (-) before α here means that the zero-load resistance decreases as the temperature rises.


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