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ADS124S08: vs ADS1148/ADS1248 for ratiometric 2-wire or 3-wire RTD measurement?

AnBer
Mastermind 30315 points
Part Number: ADS124S08
Other Parts Discussed in Thread: ADS1248, ADS1148,

Team,

We do have several collaterals for using ADS1148/ADS1248 for 2 to 4-Wire RTD measurements.
For example TIDA-00110

-Can the exact 3-wiresame topology be used with ADS124S08?
-How would look like a 2-wire measurement with ADS124S08? How many channels could be handled?
-Do you have some block diagram to share for such application?

Thanks in advance,

A.

  • 0
    TI__Guru** 113765 points

    Hi AnBer,

    I refer you to SBAA275 which is A Basic Guide to RTD Measurements which is mostly based on the ADS124S08 in the examples.  After reviewing the document, if you have any questions please ask.

    Best regards,

    Bob B

  • 0 in reply to Bob Benjamin
    TI__Mastermind 30315 points

    Hi Bob,

    Thanks!
    I did not see any reference to ADS124S08 so I was not sure if it was applying 100%.

    Also ADS124S08 has an AINCOM (Common analog input for single-ended measurements) input.
    Can it help to handle more RTD channels compare to an ADS1148/ADS1248 solution?

    Thanks in advance.

    A.

  • 0 in reply to AnBer
    TI__Guru** 113765 points

    Hi AnBer,

    The AINCOM on the ADS124S08 is the same as any other analog input.  The ADS124S08 is an upgraded version of the ADS1248 and is the preferred device to use in new designs.  All designs shown in A Basic Guide to RTD Measurements can be accomplished with the ADS124S08.  Any designs shown for the ADS1248/ADS1148 can also be used with the ADS124S08.  As the ADS124S08 has more input channels, more RTDs can be connected as compared to the ADS1248.

    Some examples for the number of RTDs that can be connected are shown in the application guide in Figures 15-17.  There are some other possible combinations as well if an external mux is used to steer the current to the various RTDs that will increase the number of possible  RTDs that can be connected.  For example, using an external mux for the IDAC current (through AINCOM) you could connect up to six 2-wire or 4-wire RTDs (using inputs AIN0-AIN11). 

    Best regards,

    Bob B