The function of NTC (Negative Temperature Coefficient) thermistors.
Categories: Industry News
2025-01-02
NTC Negative Temperature Coefficient ThermistorIt is a thermistor with a negative temperature coefficient. The resistance value characteristic decreases as the temperature increases. The material used is a semiconductor material with a large negative temperature coefficient. This type of resistor is widely used in switching power supplies, UPS power supplies, electronic ballasts, temperature sensors, automatic heating regulators, and other applications. Below, I will introduce three functions of thermistors in surge absorption, temperature measurement, and temperature compensation.
1. Suppressing Surge Current
This type of thermistor belongs to the power type. Although it is small in size, it has a high power rating. Typically, it is connected in series with the power input line. It has a rated zero power resistance, which is usually very small. The zero power resistance is a thermal resistance. The basic parameters of the resistance are usually provided by the manufacturer. When connected in series in the power circuit, it can effectively suppress the starting surge current, and the power consumed is almost negligible.
2. Temperature Sensor
Since the thermistor used for measuring temperature relies on the resistance value that changes with external temperature variations, whenthe NTC negative temperature coefficient thermistor is connected to the circuit, a certain amount of current will always flow through it. This current will cause the NTC itself to heat up, and the NTC resistance value will decrease. This has a significant impact on measurement, so it is necessary to control self-heating to avoid excessive current flowing through the thermistor, which could lead to component heating and measurement errors. The entire or partial resistance value corresponding to the temperature is written into the CPU, so that when the external temperature changes, the resistance value changes and becomes a voltage change. This comes in various packages such as chip type, epoxy resin head type, glass sealed type, and hat type.
3. Temperature Compensation
In some electrical appliances, the requirements for accuracy are very high, especially for instruments and meters made of many parts with metal wires, such as wire-wound resistors. Metals typically have a positive temperature coefficient, and negative temperature coefficient thermal sensors can be used. The resistance is compensated, with one positive and one negative, to offset the errors caused by temperature changes and improve accuracy. For temperature compensation, it is common to connect alloy copper wire resistance in parallel withthe NTC thermistor, and then connect it in series with the compensation component.
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2025/01/02
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