In standard UTI applications, the Pt100/Pt1000 is excited by a square wave voltage, via the series connection of Rbias and Rref. This works fine as long as the cables are short, under 20”. When the connecting cables need to be longer, the parasitic capacity between the connecting wires and the grounded cable shield will degrade the signal.

Because there is one signal current flowing through the three resistors, the value of RPt can be determined by measuring the ratio between the voltage over RPt and Rref. "See the application notes for a complete explanation. The DCPt provides an easy way to solve your long line issues."

Note: this board mounts directly on the UTI Eval BoardDetailed discussion of the long lead problem is presented in APPUTI08.pdf. A detailed diagram for using the DCPt is presented in DCPt.pdf.