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Introduction to NTC Thermistors with Negative Temperature Coefficient

2020-11-09

　　ThermistorThermistors are very common resistors. A thermistor is a semiconductor component whose resistance value is highly sensitive to temperature. Its main feature is that the resistance value changes with temperature. There are many types of thermistors. Today, we will focus on NTC (Negative Temperature Coefficient) thermistors.

　　Negative Temperature Coefficient Thermistoris a thermistor whose resistance value decreases as the temperature increases. The change in resistance may be caused by the external environmental temperature or by self-heating of components due to current in the circuit. The predictability of this resistance change with temperature is the basis for the application of thermistors.

Negative Temperature Coefficient thermistors are semiconductors, usually composed of transition metal oxides such as manganese, cobalt, nickel, copper, and iron, which are sintered to form different shapes and sizes. By changing the composition and morphology of the elements in the semiconductor, the resistance range of the product at room temperature can vary from 1Ω to 106Ω, and the temperature coefficient can range from -2%/°C to -6.5%/°C.

Many people believe that NTC thermistors are mainly used for temperature measurement. In fact, this understanding is very incorrect. The true purpose of NTC thermistors is to prevent surge currents in electronic circuits when turned on. Power NTC thermistors are connected in series in the power circuit, effectively suppressing surge currents during startup, and after suppressing the surge current, the resistance of the power NTC thermistor is very low, making its power consumption negligible and not affecting the normal working current. Therefore, using power NTC thermistors in power circuits is a simple and effective measure to suppress surges and protect electronic devices from damage.

The role of NTC thermistors: suitable for switching power supplies, UPS power supplies, various electric heaters, electronic energy-saving lamps, electronic ballasts, power circuit protection for various electronic devices, as well as filament protection for color cathode ray tubes, incandescent lamps, and other lighting fixtures, and they are still widely used.

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