Voltage Divider Circuit Calculator - For NTC Thermistor

A thermistor is an electronic temperature-sensing device, which exhibits a change in resistance with a relative change in temperature. The name derives from two other words, "thermal resistor". For temperature measurement and control applications, Negative Temperature Coefficient (NTC) devices are generally used. The "-t°" in the circuit symbol usually denotes an NTC device. These components are very useful for interfacing projects with microcontrollers. To use this device properly to measure temperature, a potential divider (PD) network is often the ideal circuit arrangement.

As temperature increases, Vout increases

Potential Divider Formula - With NTC

Calculator

As temperature increases, Vout decreases

Potential Divider Formula - With NTC

Calculator

NTC Temperature to Resistance

This is the standard formula from my data book, which shows how to calculate the resistance R at any particular temperature T.

R_T0 is the resistance in ohms at a given temperature T₀, which you will find in the datasheet of the device you are using. The device rating is typically a resistance value at a particular temperature, such as 4.7 kΩ at 25 °C.

Hence, R_T0 = 4700 Ω and T₀ = (25 °C + 273.15)

The formula requires all the temperaturesto be in kelvin (K) hence you need to convert by adding 273.15. The beta constant value ß is also another parameter specific for the device you are using, usually ound in the documentation for the device you are using.

NTC Charts

Manufacturers often provide a chart specific to their NTC component showing the resistance at various temperatures.

If you are unable to calculate the value, then a chart may be very useful. Unfortunately, each chart is specific for a device; hence, you will need to find this information from the manufacturer.

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