If we connect a 10K thermistor with a 10K resistor to form a voltage divider, and the voltage divider is connected to the 5V and then ground, we will get a current minimum current flow of about 25mA (5V / (10K + 10K) = 0.25mA) all the time. It is because of the self _heating phenomena. You might be wondering why we have connected the reference resistor to the GPIO2 instead of the 5V pin. From the calculated thermistor resistance, we can also calculate the temperature too. From this voltage drop, we can then calculate the resistance of the thermistor. As we know the value of the reference resistor and the reference voltage, we can calculate the resistance of the thermistor from the measured voltage drop. The voltage divider is built with the 10K resistor connected to the 5V and the Thermistor is connected to the ground, The voltage is measured where the NTC thermistor and the resistor are connected together. For this instance, we are going to use a 10K resistor for that. We are going to create a voltage divider with the NTC thermistor and a known value resistor. Since we know V in, R 1, and Vout we can calculate the value of the NTC thermistor R2 with the following equation R 2 =( Vout * R 1) / ( V in - Vout) Arduino NTC Thermistor Interfacing Circuit Diagram And the voltage divider equation is as follows. To measure the resistance of the NTC Thermistor, first, we will measure the voltage from the voltage divider. One terminal of the thermistor will be connected to the VCC line through a known value resistor and the other terminal will be connected to the ground. Measuring NTC Resistance and Temperatureįor measuring the resistance of an NTC thermistor, we will use a voltage divider. Since Li-ion batteries are highly dangerous at high temperatures it is necessary to monitor their temperature continuously. NTC thermistors are used for measuring the battery temperature. Why NTC Thermistors are used in Li-ion Battery Packs? Thermistors are non-linear variable resistance devices. Thermistors are made of sintered ceramics consisting of highly sensitive material with consistently reproducible properties of resistance versus temperature. The actual resistance values of a particular NTC thermistor are obtained by multiplying the ratio RT/R25 (tabulated value) by the resistance value at 25 ☌, which is specified in the datasheet. Its resistance will decrease when the temperature increases. NTC Thermistor is a thermally sensitive resistor with a Negative Temperature Coefficient. Here is a small animation showing the working of an NTC thermistor.Ĭommonly Asked Questions about NTC Thermistor The thermistor of course is not the best one for accurate temperature measurements, but it is damn cheap and can be used very easily. So, we can measure the resistance of the thermistor and can calculate the temperature in relation to the measured resistance. How Does an NTC Thermistor Work?Īs already mentioned, the resistance of an NTC thermistor will change with a change in temperature. When the temperature increases the resistance decreases. You can see that at 25⁰C the Resistance of the NTC thermistor is 10Kohms. Here is the Resistance Versus Temperature Response graph for the TCS610 10K NTC from wavelength electronics. NTC are commonly used as temperature sensors or in series with circuits like power supplies as an inrush current limiter. With NTC thermistors, resistance decreases as temperature rises, due to an increase in the number of conduction electrons energized by the thermal agitation from the valance band. Negative Temperature Coefficient Thermistors or NTC Thermistors They are usually used for overcurrent protection, as resettable fuses. With PTC thermistors, resistance increases as the temperature rises, usually due to increased Thermal lattice agitations. Positive Temperature Coefficient Thermistors or PTC Thermistors Positive Temperature Coefficient Thermistors or PTC Thermistors.Negative Temperature Coefficient Thermistors or NTC Thermistors.Terminal 2 NTC Thermistor terminal 2 Types of Thermistorsĭepending on the materials used and how they react with the temperature thermistors are classified into two types: Thermistors are used in various everyday use items like Thermostats, SMPS, surge protection circuits and rechargeable battery packs, etc. This feature enables us to read the temperature or change in temperature by measuring the resistance of the thermistors. Thermistors or THERMally sensitive resISTORs are variable resistors, whose resistance will be changed with the temperature. Thermistors are simple, inexpensive, and accurate components that make it easy to get temperature data for your projects.
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