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What are NTC Thermistors used for?

With over 20 year’s experience in the thermal controls industry, ATC Semitec is the country’s leading distributor of thermal components.  NTC thermistors are a key part of our business and in this article we will attempt to explain firstly, what NTC Thermistors are and then secondly, suggest some possible uses.  If you then feel they may help solve your temperature sensor or thermal safety requirements, please contact us at ATC Semitec and we will be happy to advise further.

What Are NTC Thermistors?

Thermistor is a compound word formed of “thermal” and “resistor”, while the acronym NTC denotes specifically a Negative Temperature Coefficient thermistor where the device resistance falls as the temperature rises.  Temperature sensitive with a clearly-defined characteristic, these solid state sensors are in effect a form of variable resistor.

Their benefits are many and varied.  For instance they have a very high T.C.R. (Temperature Coefficient of Resistance), are widely available, easy to use and very affordable, while also being highly adaptable.  Not usually the first choice for measuring very high temperatures, their decent output voltages are very effective for simple temperature measurements and are incredibly accurate at temperatures lower than 300°C .  

The very popular Semitec AT series

Constructed of temperature-sensing ceramics, thermistors feature a semi-conducting element, which is sintered (formed into a solid mass via heating in a furnace) so that even small changes in temperature can effect a large change in resistance.  A very small direct current is passed through the thermistor, so that the voltage drop can be measured as the thermistor temperature/resistance changes.  NTC thermistors are non-linear, so the resistance decreases logarithmically as the temperature increases. The standard resistance value for most thermistors is usually specified at 25°C, known as the R25 value. The other main parameter is the B value, often specified between 25°C and 85°C

What Are NTC Thermistors Used For?

Broadly speaking, NTC thermistors find applications in temperature control, temperature compensation and temperature measurement. Extremely accurate and highly versatile, their utility finds them in a wide range of applications:

  • The car industry

Demand has been massive in the car industry, with manufacturers using around 20 NTC thermistors in the average new car.  You will now find them as components in fuel systems, safety systems, engine monitoring and cabin climate control.  Exhaust gas monitoring (EGR sensors) has been especially key with changes to emissions regulations in modern cars.

Semitec JT Film Thermistor
  • Industry

NTC thermistor sensors can be found throughout industry, in everything from flexible heating elements and plastic laminating machines, through to soldering irons, hot glue-guns, photo-copiers, laser printers and naturally smoke and fire detectors.  They can also be found in science labs and calibration equipment including anemometers and bolometers.

  • From the Domestic…

If you feel none of this relates to you or your domestic environment, you may be surprised to hear there are NTC thermistors in the humble domestic burglar alarm, your room thermostat, electric oven, fire detector.…even your fridge.  If you have ever used a digital thermometer to take your child’s temperature, there will have been one in there too.

  • …to the otherworldly

Beyond the domestic, commercial and transport markets, NTC thermistors have found their way into everything from medical and military to scientific applications, everywhere from missiles to oceanographic exploration.  They have even been used in spacecraft! There are NTC thermistors to suit every possible need, and at ATC Semitec we have the leading range of reliable, durable models built to survive high temperatures, for long periods of time. Built from a variety of quality materials and available in a range of fully customisable designs, we believe we have an NTC thermistor to suit nearly every possible requirement. 

Simply contact ATC Semitec on 01606 871680 and we will walk you through the options and find the right thermistor solution for you