Temperature sensor

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Temperature sensors are mostly electrical or electronic components that deliver an electrical signal as a measure of the temperature .


Components that change their resistance

  • NTC thermistors reduce their resistance when the temperature rises, they are based on metal oxides or semiconductors and are also called thermistors when they are used for measuring purposes .
  • PTC thermistors increase their resistance when the temperature rises.
    • Platinum measuring resistors have an almost temperature -linear resistance curve. Depending on the version, they can be used between −200 ° C and +850 ° C.
    • Silicon measuring resistors are used in the temperature range from −50 ° C to +150 ° C.
    • Ceramic PTC thermistors show a strong increase in resistance at a material-specific temperature. They can also be used as a self-regulating heating element or as a thermal fuse .

Components that directly supply a processable electrical signal

  • Deliver integrated semiconductor temperature sensors ( solid state circuits )
    • a current proportional to its temperature (example: AD592, proportional to the absolute temperature 1 µA / K)
    • a voltage proportional to its temperature (example: LM335, 10 mV / K)
    • a digital signal depending on its temperature (examples: AD7314, DS18B20)
  • The base-emitter voltage of a transistor connected as a diode decreases with increasing temperature (depending on the current; guide value at 1 mA 2.3 mV / ° C).

Further procedures

Other terms for temperature sensors are: heat sensor, temperature sensor, heat sensor.

Integrated temperature sensors

Temperature sensors are built into many integrated circuits in order to achieve temperature-dependent regulation or protection against overheating. Temperature measuring devices or temperature threshold switches can be found, for example:

  • in microprocessors as overtemperature protection: when a temperature threshold is reached, for example, the clock frequency is reduced in order to avoid a further increase in temperature.
  • in DRAM memories to control the refresh frequency, which is highly temperature-dependent (it has roughly an exponential behavior)
  • in power semiconductors and power supply IC as overheating protection (e.g. sometimes also in power MOSFET )

See also

Web links

Wiktionary: Temperatursensor  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. Data sheet AD592
  2. data sheet LM335
  3. Data sheet AD7314
  4. Description of the DS18B20
  5. Data sheet DS18B20
  6. Miklos Herpy, Analog Integrated Circuits , 1976, Franzis, p. 58