Thermistors are typically sensitive to temperature and exhibit different resistance values at different temperatures. It is divided into positive temperature coefficient PTC thermistor and negative temperature coefficient NTC thermistor. The resistance value of positive temperature coefficient PTC thermistor increases with the increase of temperature, and the resistance value of negative temperature coefficient NTC thermistor decreases with the increase of temperature. They are both semiconductor sensitive components.
PTC thermistor is mainly used in overcurrent overheat protection, color TV degaussing, motor starting, constant temperature heating, etc.
NTC thermistor is mainly used for temperature compensation, inrush current suppression, temperature detection and flow measurement.
In electronic circuits, NTC thermistors are used for temperature compensation because the characteristics of many components (such as coils, crystal oscillators, transistors, LCD panels, etc.) change with the change of temperature and have positive temperature coefficients. The NTC thermistor compensates for the deviation of electrical signals caused by changes in ambient temperature to enable the components to operate properly over a wide range of temperatures.
NTC thermistor is used to suppress inrush current and has the characteristics of simple circuit and reliable operation. Switching power supply circuit, lighting circuit, etc. in the opening opportunity to produce a large surge current, its peak can reach the normal working current of about 10-100, up to hundreds of amperes. Cause the failure of electronic equipment, or the entire circuit and equipment damage. Using the NTC thermistor i-v characteristics and current - time characteristic, and load it in series, NTC thermistor resistance prior to power is larger, after electrify the NTC thermistor temperature rise due to the effect of current, the NTC thermistor resistance is reduced, after effectively suppress surge current, NTC thermistor itself low power consumption, It will not affect the normal working current.
The NTC temperature sensor is a kind of thermistor. The working principle of the NTC temperature sensor is that the resistance value decreases rapidly as the temperature rises. NTC temperature sensor has the characteristics of accurate temperature measurement, low cost, small size and high sensitivity. When THE NTC thermistor as a temperature measuring element, because the NTC thermistor resistance value - temperature has a strict characteristic law, so by detecting the NTC thermistor resistance value can detect the temperature of THE NTC thermistor.
When NTC thermistor is used for flow measurement, the flow rate of gas or liquid is proportional to the cooling rate of NTC thermistor, and the flow rate can be easily calculated by measuring the change of the resistance value of NTC thermistor.
