Editing Thermistor (section)

== Types ==

Depending on materials used, thermistors are classified into two types:

*With ''NTC'' thermistors, resistance decreases as temperature rises; usually because electrons are bumped up by thermal agitation from the valence band to the conduction band. An NTC is commonly used as a temperature sensor, or in series with a circuit as an [[inrush current limiter]].
*With ''PTC'' thermistors, resistance increases as temperature rises; usually because of increased thermal lattice agitations, particularly those of impurities and imperfections. PTC thermistors are commonly installed in series with a circuit, and used to protect against overcurrent conditions, as resettable fuses.

Thermistors are generally produced using powdered metal oxides.<ref>{{Cite web |url=https://www.ei-sensor.com/what-is-a-thermistor/ |title=What is a Thermistor? How do thermistors work? |website=EI Sensor Technologies |language=en-US |access-date=2019-05-13}}</ref> With vastly improved formulas and techniques over the past 20 years{{when|date=December 2020}}, NTC thermistors can now achieve accuracies over wide temperature ranges such as ±0.1&nbsp;°C or ±0.2&nbsp;°C from 0&nbsp;°C to 70&nbsp;°C with excellent long-term stability. NTC thermistor elements come in many styles <ref>{{Cite web |url=https://www.ei-sensor.com/thermistors/ |title=Thermistors |website=EI Sensor Technologies |language=en-US |access-date=2019-05-13}}</ref> such as axial-leaded glass-encapsulated (DO-35, DO-34 and DO-41 diodes), glass-coated chips, epoxy-coated with bare or insulated lead wire and surface-mount, as well as thin film versions. The typical operating temperature range of a thermistor is −55&nbsp;°C to +150&nbsp;°C, though some glass-body thermistors have a maximal operating temperature of +300&nbsp;°C.

Thermistors differ from [[Resistance thermometer|resistance temperature detectors]] (RTDs) in that the material used in a thermistor is generally a ceramic or polymer, while RTDs use pure metals. The temperature response is also different; RTDs are useful over larger temperature ranges, while thermistors typically achieve a greater precision within a limited temperature range, typically −90&nbsp;°C to 130&nbsp;°C.<ref>[http://www.microchiptechno.com/ntc_thermistors.php "NTC Thermistors"] {{Webarchive|url=https://web.archive.org/web/20170922072623/http://www.microchiptechno.com/ntc_thermistors.php |date=2017-09-22 }}. Micro-chip Technologies. 2010.</ref>