A negative temperature coefficient (NTC) thermistor (JNR) is made of specially formulated metal oxide ceramic material, which can be used to suppress instantaneous surge current.

Compared with the protected circuit, the surge current limiting element has a higher resistance, so it will suppress the surge current for about 1 to 2 seconds. During this period of time, the resistance will drop due to the increase in temperature until the voltage across the thermistor Down to the point where it can be ignored. Take the power supply as an example. At the moment when the power is turned on, the impedance of the capacitor is extremely low, and the bridge rectifier usually flows a large current. Therefore, JNR thermistors are widely used to protect the power supply.