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a semiconductor device having a resistance that decreases rapidly with an increase in temperature. It is used for temperature measurement, to compensate for temperature variations in a circuit, etc.
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005


An electrical resistor with a relatively large negative temperature coefficient of resistance. Thermistors are useful for measuring temperature and gas flow or wind velocity. Often they are employed as bolometer elements to measure radio-frequency, microwave, and optical power. They also are used as electrical circuit components for temperature compensation, voltage regulation, circuit protection, time delay, and volume control. Thermistors are semiconducting ceramics composed of mixtures of several metal oxides. Metal electrodes or wires are attached to the ceramic material so that the thermistor resistance can be measured conveniently. See Bolometer, Electrical resistivity

At room temperature the resistance of a thermistor may typically change by several percent for a variation of 1° of temperature, but the resistance does not change linearly with temperature. The temperature coefficient of resistance of a thermistor is approximately equal to a constant divided by the square of the temperature in kelvins. The constant is equal to several thousand kelvins and is specified for a given thermistor and the temperature range of intended use.

The resistance and heat capacity of a thermistor depend upon the material composition, the physical dimensions, and the environment provided by the thermistor enclosure. Thermistors range in form from small beads and flakes less than 10-3 in. (25 micrometers) thick to disks, rods, and washers with inch dimensions. The small beads are often coated with glass to prevent changes in composition or encased in glass probes or cartridges to prevent damage. Beads are available with room-temperature resistances ranging from less than 100 &OHgr; to tens of megohms, with heat capacities as low as tens of microwatts per degree celsius, and with time constants of less than a second. Large disks and washers have heat capacities as high as a few watts per degree Celsius and time constants of minutes. See Temperature measurement, Time constant

McGraw-Hill Concise Encyclopedia of Physics. © 2002 by The McGraw-Hill Companies, Inc.


A resistive circuit component, having a high negative temperature coefficient of resistance, so that its resistance decreases as the temperature increases; it is a stable, compact, and rugged two-terminal ceramiclike semiconductor bead, rod, or disk. Derived from thermal resistor.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
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PTC thermistors are normally mounted near the component they are protecting to ensure proper thermal contact, resulting in the fastest response time.
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[6] Steinhart J, Hart S (1968) Calibration curves for thermistors. Deep Sea Research and Oceanographic Abstracts 15(4):497-503.
A thermistor is a type of resistor whose resistance varies significantly with temperature, more so than in standard resistors.
Nevertheless, RTDs and thermistors are relatively easy to use because they do not have a TC's need for CJ temperature correction.
The SMD PTC thermistors can be used in the fan controllers of notebooks in order to avoid critical temperatures.
Thermistors typically have a stability of [+ or -]0.2[degrees]C ([+ or -]0.1[degrees]F) but they can be as stable as [+ or -]0.1[degrees]C (0.06[degrees]F) when using extra precision (XP) thermistors.
Data from the thermistors' resistance measurement gauges was transmitted to analog-to-digital converters and passed in digital form to computer for data processing.
Finally, we also investigated whether the brain lesions caused by the chronic implantation of a guide cannula or acute thermistor insertion for measuring [T.sub.brain] affected performance.
Optimized for ultra-stable thermoelectric temperature control applications, the WTC3243 maintains precision temperature regulation using an adjustable sensor bias current and error amplifier circuit that operates directly with thermistors, RTDs, AD590, and LM335 type temperature sensors.