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RTD input stage

Pasquale De Sando
Prodigy 120 points


Hi all,

I need to develop an analog front-end stage for RTD probes (PT100 and PT1000) for an industrial application.
I've noted that in many application notes a +/-15V dual power supply is used, as in the following example:

 

There is some particular reason to this?
Is this due to a some normative for industial environment?

thanks

 

  • 0
    Prodigy 20 points

    A dual rail supply source is an easy way of keeping all the input and output signals within the common mode ranges of the opamp device.

    Conventional opamps cannot operate with input or output signals near the supply rails.

    You can substitute with a rail-to-rail I/O opamp (but these devices sacrifice some performance attributes to be able to do this).

    You can use Thevenin and Norton equivalent source transformations to work out new resistor values to replace the "ground" node in the original circuit.

    There is a good guide at http://www.ti.com/lit/an/sloa030a/sloa030a.pdf