Termination resistor in RTD analog front end.

Thread Starter

Eduardo Hernando Torres

Joined Oct 15, 2018

First of all sorry for my English, it is not my first language and sometime I cannot make myself completely clear.

I am in a project in which I would like to use RTD in order to measure temperature in several points, as usual, when I have to do an analog design, since it is not my strongest point I try to find some application note to get ideas.

In this case I have found an application note from TI (TIDU575–December 2014) which I have found very interesting, but I am struggling to understand why they are using 247R resistors at the end of the analog stage, after the filter and just before the ADC.
It remainds me of the termination resistor that are usually used for impedance matching in transmission lines to avoid wave reflections, but I dont get it in this case, I hava also consulted the articles in the documentation section and neither of them use this resistor.

I have also consulted the datasheet of the ADC (ADS1248) but I cannot find any reference to that.

All the opinions and advices are more than welcome, thank you in advance

The circuit I am talking about: