The NTC Thermistor in the LED Lighting System

Thermistor is a kind of sensitive component made of semiconductor material, which is sensitive to temperature, and whose resistance value changes with the change of temperature. Because of its high sensitivity to temperature, it can detect subtle temperature changes and is used as a temperature sensor in electronic products.


In addition to being used as a temperature sensor, the thermistor can also be used as a temperature protection device to protect the circuit from overheating and is used in LED lighting.


LED lighting is widely used. However, there is a problem with LED lighting during use: poor heat dissipation. Due to the small space and poor heat dissipation of LED lights, it is easy to overheat, which reduces the working performance of LED lights and greatly shortens the use time.

led light

In the LED lighting system, the semiconductor PN junction surface as the light-emitting layer will generate heat, and the temperature of the junction surface is the junction temperature. When the current flowing through the LED lighting system becomes larger, the brightness of the LED light increases, and the temperature also increases. Excessive temperature will affect the service life of LED lamps, reduce working performance and increase unnecessary costs. In order to improve the efficiency of LED lights, LED lights need to work at a suitable temperature, and at this time it depends on the thermistor.


Thermistors are divided into positive temperature coefficient thermistors and negative temperature coefficient thermistors according to the temperature coefficient. Which kind of thermistor should be used in LED lights?


The thermistor on the LED lighting system uses a negative temperature coefficient thermistor, that is, an NTC thermistor.


The resistance of the NTC thermistor decreases as the temperature rises. The resistance of the thermistor is small when it is working, so when the current flowing through the thermistor becomes larger, the current flowing through the LED lighting system becomes larger, and the brightness of the LED light becomes larger, the temperature also increases; but the operating temperature range of the thermistor is limited, beyond the temperature range, the resistance of the thermistor will increase, the resistance increases to limit the current, reduce the output of the current, and avoid the high temperature caused by the excessive current, which will cause the LED light overheating and reduced performance.


Therefore, the NTC thermistor is embedded in the circuit, and after thermal coupling with the LED lighting system, the protection circuit works. When the proper working temperature of the LED lighting system deviates, the resistance of the NTC thermistor also changes accordingly, and compensates the current flowing through the LED lighting system, and controls the temperature of the LED lighting system within the specified temperature range to ensure that the normal operation of the LED lamp, reduce the power consumption of the LED lamp and prolong the working time of the LED lamp.


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Post time: Mar-13-2023