Characteristics of Thermistors - NTC and PTC


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Thermistors are thermal sensitive resistors whose primary function are to exhibit a change in electrical resistance with changes in temperature.

NTC (Negative Temperature Coefficient) thermistors

  • zero-powered resistance (no power dissipated)
  • its resistance decreases with an increase in temperature NTC

The resistance of an NTC is sensitive to temperature changes in a generally linear manner. It is normal to choose NTC thermistors when a continuous linear change of resistance with temperature is required, such as temperature compensation, temperature control systems and inrush current limiting.

PTC (Positive Temperature Coefficient) thermistors

  • zero-powered resistance (no power dissipated)
  • its resistance increases with an increase in temperature PTC

PTC exhibits only a slight change of resistance with temperature until the “switching point” is reached, at which point an increase of several orders of magnitude in resistance occurs. It is normal to choose a PTC thermistor for self reset-capable fuses and heater applications.