Thermistors are a type of semiconductor, meaning they have greater resistance than conducting materials, but lower resistance than insulating materials. The relationship between a thermistor’s temperature and its resistance is highly dependent upon the materials from which it’s made and is referred to as the temperature coefficient. It is composed of materials with known resistance and that are available in two types: those with negative temperature coefficients (NTC) and those with positive temperature coefficients (PTC). NTC thermistors’ resistance decreases as their temperature increases, while PTC thermistors’ resistance increases as their temperature increases. NTC thermistors are commonly used in temperature measurement where small size is important, such as handheld devices and building heating controls.

Thermistors are available with a variety of base resistances and resistance vs. temperature curves. They generally use lower resistance in the 2 kΩ to 10 kΩ range for low temperature applications (–55°C to approximately +70°C). Higher temperature applications generally use higher resistance thermistors of above 10 kΩ. Resistances are normally specified at 25°C with a temperature coefficient specified in Ω/°C. They are accurate to approximately ±0.2°C within their specified temperature range and are durable, long-lasting, and inexpensive.

Using Custom Thermistors with the Temp-to-Bits Family

Using Custom Thermistors with the Temp-to-Bits Family

This article focuses on custom thermistors and two ways of configuring the converter.

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This Should Work: Thermistor Senses Liquid Levels

This Should Work: Thermistor Senses Liquid Levels

In precision temperature measurement applications using thermistors, RTDs, or other resistive temperature sensors, care must be taken to avoid errors due to self-heating of the sensor by the excitation current.

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Signal Chains


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Reference Designs

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