What Is an NTC Thermistor? Working Principle, Applications, and Failure Detection

An NTC (Negative Temperature Coefficient) thermistor is an essential component used in the power supply section of electronic devices. It is commonly connected in series with the AC input line and is responsible for suppressing inrush current at the moment of power-up.     Structure and Principle of NTC Thermistor An NTC thermistor consists of a semiconductor ceramic element whose resistance decreases as the temperature rises. At room temperature, it maintains high resistance, limiting the inrush current when power is first applied. As the device warms up, the resistance rapidly drops, allowing stable current flow with minimal power loss. Main Functions of NTC Thermistor Suppressing inrush current: protects bridge diodes and capacitors from surge damage Gradual startup of power supply: ensures smooth charging of electrolytic capacitors Thermal protection: can act as a safety element if placed near heating elements     ...