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Original question:

ADS1248: External Reference voltage

ADS1248: Input ground reference

Saribel Daza
Prodigy 50 points
Part Number: ADS1248
Other Parts Discussed in Thread: ADS1247

Thank you for your feedback regarding the 5V external reference voltage!  In light of your feedback, the re-design approach has changed:

   From: Using 5V_REFERENCE, which is a more regulated 5V available on the PCBA design, for both

             (1) the reference voltage to the transducer, which is an input to ADS1248

                  and

             (2) an external reference voltage for the ADS1248

   To:     Using the 5V_REFERENCE only as a reference voltage to the transducers, which are inputs to the ADS1248

The 5V_REFERENCE has its' own ground (triangle ground symbol) separate from the +5V ground (parallel line symbol ground seen in the schematic).  Since the input to ADS1248 is referenced to the 5V_REFERENCE ground, which other ADS1248 pins should be referenced to the 5V_REFERENCE ground?

  • 0
    TI__Guru** 113765 points

    Hi Saribel,

    All analog inputs should be referenced to analog ground.  As you are supplying both AVDD and DVDD from the same source voltage, then all the grounds should be tied together preferably in a ground plane.  So from your schematic, all the grounds should tie together on the PCB.

    I would suggest that you also include antialiasing input filters from the output of the pressure sensor to the inputs of the ADS1247.  This can be a simple RC filter.

    Best regards,

    Bob B