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ADS127L21: What is the INL, if I use symmetrical supply for the analog part?

Friedrich Kaufmann
Prodigy 70 points
Part Number: ADS127L21

Tool/software:

Hello,

in the datasheet of the ADS127L21 all interesting parameters are specified for AVSS=0V and AVDD1= 5V, that is to say, the analog part has unsymmetrical supply.
I would like to use symmetrical supply with AVSS=-2.5V and AVDD1=2.5V.
Is there any change of the specifications, if I use symmetrical supply instead of the specified unsymmetrical supply?
I suppose, that the ICs are tested with unsymmetrical supply and therefore the specifications can be only guaranteed for unsymmetrical supply.
Perhaps there is a guarantee by design, that the specifications are independent of the kind of supply, as long as the difference between AVDD1 and AVSS is 5V and the voltages are in the recommended range.
For me the most interesting specification is the linearity, defined by the INL.

best regards,
Kaufmann Friedrich  

  • +1
    TI__Mastermind 40860 points

    Hello Kaufmann Friedrich,

    We exhaustively tested the ADS127L21 with a single 5V supply, which is why all of the specifications in the datasheet are for AVSS=0V and AVDD1=5V.  However, there is no reason to expect any of the specifications to be different when operating from bipolar +/-2.5V supplies. 

    I have not directly measured linearity with +/-2.5V supplies, but I have looked at SNR and THD, and neither value changed with +/-2.5V supplies.  Since THD is directly related to INL, this strongly suggests that there will be no differences in INL performance based on the analog supply configuration.

    Regards,
    Keith Nicholas
    Precision ADC Applications