Main parameter about NTC thermistor
1. Zero-power resistance (RT)
The zero-power resistance is the value of a resistance when measured at a specified temperature, under conditions such that the change in resistance due to the internal generation of heat is negligible with respect to the total error of measurement.
2. Rated zero-power resistance R25
The rated zero-power resistance is the nominal value at the standard temperature of 25℃ unless otherwise specified.
3. B constant in Kelvin’s (K)
B constant is an index of the thermal sensitivity expressed by the formula:
4. Dissipation factor(δ)
Dissipation factor (δ) is power in milliwatts required to raise thermistor temperature 1℃.Measured with thermistor suspended by its
leads in a specified environment.
5. Thermal time constant (τ)
Thermal time constant (τ) is the time required by a thermistor to change 63.2% of the difference between its initial and final temperature. Measured with thermistor suspended by its leads in specified environment.
6. Power rating
Rated power=heat dissipation factorδ × (maximum operating temperature－25℃)
7. Resistance/temperature characteristic
The relationship between the zero-power resistance of a thermistor and its body temperature. The resistance law follow approximately the formula: