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ADS1202: Measuring static parameters

Part Number: ADS1202

Hello, thank you very much for help with ADS1202. I`ve got a good spectrum.

But I have a question about measuring static parametres of this ADC. How should I get points for transfer function to measure INL? Are they the mean values of some convertions of one voltage level?

Also what is procedure for measuring DNL?

  • Hi Maria!

    Glad to hear that you've got a clean spectrum now!  For INL and DNL, you could use a ramp waveform that covers the FS- to FS+ input range.  INL is the deviation of an output code from the ideal mid-point in the transition step.  DNL is the deviation of the code width output versus the analog input.  Please take a look at this TI Precision Labs video for more details.

  • Hello, Tom, thanks for reply!

    I usually use this method to form a ramp waveform to get the transfer function:
    1) set up the min voltage level = -FS on analog input
    2) make a conversion
    3) increase voltage level on analog input on step=76uV (the least step I can make)
    4) make another conversion
    and so on up to the FS.
    Is it appropriate in case of sigma-delta ADC? Which step should I use to make ramp? How many points were taken to get INL simular to the one from datasheet?

  • Hi Maria,

    Yes, you can use that method as well, however the ideal measurement would need a source with greater resolution than the ADC itself.  What is the source of your input signal?  The ADS1202 shows 16-bit resolution so your LSB size is actually about 10x smaller than your smallest step available to the input.  you may be able to extrapolate some information.  I do not know how many points were taken for the plots in the datasheet.  What you would want to do is average 100 points or more for each input step and see what you get.