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ADS124S08: ADS124S08 INL/DNL spec issue

ele
Prodigy 60 points
Part Number: ADS124S08


Hi, 

    We are trying to use ADS124S08 to build a high accuracy data acquisition board.  We need to make sure that the ADS124S08 is good enough, from the spec the INL is around 1~3 ppm,  we are confuse about this INL value. It seem that it is not possible to get this value from production line. 

time caculation:

2^24 = 16777216 code,

sample rate = 4000 S/s, 

To get each output code of the ADC value, it will take the time around: 

16777216 / 4000 / 3600 = 1.1 hours, 

So from the calculation above, it seem it's not possible to get this INL value from the poduction line as the test time is too high , I think you can get this from Lab validation, but how do you make sure each ADS124S08 chip from production line have the same value with the one in the Lab? 

How can I verify this INL value of this chip before soldering?  

  • 0
    TI__Guru 53736 points

    Hi Yong,

    Indeed it is challenging to measure INL so precisely. We have very special testing equipment to do so in production.

    Here is a link to a post that discusses one method to measure INL: https://e2e.ti.com/support/data-converters/f/73/p/944642/3490213#3490213

    -Bryan

  • 0 in reply to Bryan Lizon86
    TI__Guru 53736 points

    Hi Yong,

    Also, in case you were wondering since it is mentioned in the thread title, delta-sigma ADCs generally do not specify DNL. Since these ADCs have high resolution (often 24 bits), the noise is larger than the DNL value, which is typically very low. This is the case for the ADS124S08, and why you do not see a DNL measurement in the datasheet.

    -Bryan

  • 0 in reply to Bryan Lizon86
    Prodigy 60 points

    Hi Bryan,

        Thanks a lot for the reply, from the link you provided,  TI would measure the ADC  INL in the Lab with only some special voltage point. Is it the same in the production line?  Only check a few voltage point to save the test time?

  • 0 in reply to ele
    TI__Guru 53736 points

    Hi Yong,

    I understood your question was asking how you could measure the INL of an ADC, not so much how TI measures INL in production. The link I provided is a methodology for you to try to verify the INL of your device, though it takes high precision meters / sources to be able to do so. Suffice it to say that if there is an INL spec in an ADC datasheet, it is verified in production according to the datasheet. Without getting too deep into the details of how INL is tested in production, I can say that any device that falls outside the min/max specs would be discarded, so you should feel confident in the INL specs provided.

    Again, if you would like to verify INL, the link I provided is one way to do so.

    -Bryan

  • 0 in reply to Bryan Lizon86
    Prodigy 60 points

    Hi Bryan,

       OK, get it. Thanks for the reply.