Temperature measurement circuit composed of the AD7714 and Pt100

Published:2011/7/7 2:11:00 Author:Christina | Keyword: Temperature measurement | From:SeekIC

The temperature measurement circuit which is composed of the AD7714 and Pt100 is as shown in the figure. The Pt100 uses the 4-wire connection method, this method can eliminate the voltage drop of the lead resistances RL3 and RL2. The external 400μA current source supplies the PT100 excitation current, and this current produces the reference voltage of AD7714 through the 6.25kΩ resistance. Because the change of input voltage and the reference voltage is proportional to the change of the excitation current. so the change of excitation current will not affect the measurement precision. In order to avoid the influence of the temperature change, the 6.25kΩ resistance need to use the low temperature coefficient metal film resistance.



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