nicklas_a74
Member level 1
Hi
I need an accurate and temperature stable current source to be used
between e.g. 0C to +50C. The current source should drive an PT100
and would be placed (experience the same temp interval) at the same
location. The measurement accuracy should be between 0.1C to 0.5C.
I have seen circuits using eg a voltage reference+transistor what would generate
Ic= (Vref-0.7)/R. However how accurate is this circuit if temp= 0C to +50C where PT100 should be used? Also the UBE is usually between 0.6V to 0.75 V which also influence the accuracy of the Ic.
Also there are circuits using eg LM334 which could be compensated for temperature inaccuracies (by placing an additional diode). But these give an rather high deviation in accuracy of the set current.
Please need advice for an working can accurate circuit.
I need an accurate and temperature stable current source to be used
between e.g. 0C to +50C. The current source should drive an PT100
and would be placed (experience the same temp interval) at the same
location. The measurement accuracy should be between 0.1C to 0.5C.
I have seen circuits using eg a voltage reference+transistor what would generate
Ic= (Vref-0.7)/R. However how accurate is this circuit if temp= 0C to +50C where PT100 should be used? Also the UBE is usually between 0.6V to 0.75 V which also influence the accuracy of the Ic.
Also there are circuits using eg LM334 which could be compensated for temperature inaccuracies (by placing an additional diode). But these give an rather high deviation in accuracy of the set current.
Please need advice for an working can accurate circuit.
