NTC - Negative Temperature Coefficient resistors is used in many places for measuering … temperature.
The 4th order approximination formula
Normal way of operation
The schematics below shows a standard setup.
By use of a voltage divider its easy to calculate the resisatcne of the NTC when knowing supply voltage
About proper selection of resistor in series with the NTC
Take a look at the figure below for at 10 kOhm NTC
Schematic - from above --------------- Rldr == resistance of LDR Vo = Vcc * ( Rldr / (Rldr + R) ) Vo * (Rldr + R) = Vcc * Lldr Rldr * ( Vcc - Vo ) = R * Vo Rldr = R * ( Vo /( Vcc - Vo) ) QED comment: you need to know Vs and R
In the datasheet just below you will find the approximation for calculation of temperature from measured resistance.
Its a 4th order approximation