Temperature measuring circuit with 5 channel low power programmable sensor signal processor AD7714 and Platinum thermal resistor Pt100 (PRTD)

Published:2012/11/29 0:55:00 Author:Ecco | Keyword: Temperature measuring, 5 channel , low power , programmable sensor , signal processor , Platinum , thermal resistor | From:SeekIC

Pt100 uses 4-wire connection to eliminate pressure drop on lead resistors RL2 and RL3. External 400 μA current source provides excitation current for PT100, and then it will generate AD7714 voltage reference after passing 6.25kΩ resistor. Because the input voltage and reference voltage changes and the excitation current changes are proportional, the changes do not affect the measurement accuracy of the excitation current. But in order to avoid voltage reference from the effects of temperature changes, 6.25kΩ resistor should use metal film resistors with low temperature coefficient.



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