NTC stands for “Negative Temperature Coefficient”. NTC thermistors are resistors with a negative temperature coefficient, which means that the resistance decreases with increasing temperature. It is made of manganese, cobalt, nickel,copper and other metal oxides as the main materials by ceramic process. These metal oxide materials have semiconducting properties because they are completely similar to semiconducting materials such as germanium and silicon in the way of conducting electricity. The following is an introduction to the use method and purpose of NTC thermistor in the circuit.
When an NTC thermistor is used for temperature detection, monitoring or compensation, it is usually necessary to connect a resistor in series. The selection of the resistance value can be determined according to the temperature area that needs to be detected and the amount of current flowing. In general, a resistor with the same value as the normal temperature resistance of NTC will be connected in series, and the current flowing through is guaranteed to be small enough to avoid self-heating and affect the detection accuracy.The detected signal is the partial voltage on the NTC thermistor. If you want to get a more linear curve between the partial voltage and the temperature, you can use the following circuit:
The uses of NTC thermistor
According to the characteristic of negative coefficient of NTC thermistor, it is widely used in the following scenarios:
1. Temperature compensation of transistors, ICs, crystal oscillators for mobile communication equipment.
2. Temperature Sensing for Rechargeable Batteries.
3. Temperature Compensation for LCD.
4. Temperature compensation and sensing for car audio equipment (CD, MD, tuner).
5. Temperature compensation for various circuits.
6. Suppression of inrush current in switching power supply and power circuit.
Precautions for the use of NTC thermistor
1. Pay attention to the working temperature of the NTC thermistor.
Never use the NTC thermistor outside the operating temperature range. The operating temperature of the φ5, φ7, φ9, and φ11 series is -40~+150℃; the operating temperature of the φ13, φ15, and φ20 series is -40~+200℃.
2. Please note that NTC thermistors should be used under rated power conditions.
The maximum rated power of each specification is: φ5-0.7W, φ7-1.2W, φ9-1.9W, φ11-2.3W, φ13-3W, φ15-3.5W, φ20-4W
3. Precautions for use in high temperature and high humidity environments.
If the NTC thermistor needs to be used in high temperature and high humidity environment,the sheath type thermistor should be used and the closed part of the protective sheath should be exposed to the environment (water, moisture), and the opening part of the sheath will not be in directly contact to water and steam.
4. Can not be used in harmful gas, liquid environment.
Do not use it in a corrosive gas environment or in an environment where it will come into contact with electrolytes, salt water, acids, alkalis, and organic solvents.
5. Protect the wires.
Do not overstretch and bend the wires and do not apply excessive vibration, shock and pressure.
6. Keep away from heat-generating electronic components.
Avoid installing electronic components that are prone to heat around the power NTC thermistor,It is recommended to use products with higher leads at the upper part of the bent foot, and use NTC thermistor to be higher than other components on the circuit board to avoid heating affecting the normal operation of other components.
Post time: Jul-28-2022