nicklas_a74
Member level 1
Hi
I need to measure between -40C to +70C with an accuracy
of 0.5C or better by using 2 series resistors (Rs, R2) in series
with an NTC in parallel with an resistor RP, see circuit below.
How could I calculate the accuracy of the used circuit below?
I have seen the following equations
alpha=(1/Rtemp)*(dT/dR), accuracy=R_tolerance*alpha
at a specific temperature. But how to calculate the accuracy
of an NTC in parallel with a resistance RP, as in the figure below?
The signal V1 (measured over gnd and parallel circuit) and V2 (
measured over R2) is connected to an OP to get a differential
measurement.
If using an "look up table" based upon the mean resistance vs temp
value of an NTC with R25=1% is it possible to get 0.5C accuracy over the
desired range?
Grateful for detailed help
I need to measure between -40C to +70C with an accuracy
of 0.5C or better by using 2 series resistors (Rs, R2) in series
with an NTC in parallel with an resistor RP, see circuit below.
How could I calculate the accuracy of the used circuit below?
I have seen the following equations
alpha=(1/Rtemp)*(dT/dR), accuracy=R_tolerance*alpha
at a specific temperature. But how to calculate the accuracy
of an NTC in parallel with a resistance RP, as in the figure below?
The signal V1 (measured over gnd and parallel circuit) and V2 (
measured over R2) is connected to an OP to get a differential
measurement.
If using an "look up table" based upon the mean resistance vs temp
value of an NTC with R25=1% is it possible to get 0.5C accuracy over the
desired range?
Grateful for detailed help
