• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 82 subscribers
  • Views 393 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TMS320F280025: Internal ADC reference drift

Heiko Gerdes
Prodigy 20 points
Part Number: TMS320F280025


Dear support team,

I am using the internal reference of  the ADC in a high volume charger project and need to calculate the measurement precision of my design. From the data sheet I only get the total gain error of +- 45 digits. This is probably the worst case sum of typical errors like: gain error, calibration error, supply voltage drift, temperature drift, etc. We can calibrate out all static errors (initial error) but to calculate performance we would need drift parameters. (Temperature coefficient and long term drift). I am sure TI has this data. Can it be made public or can I get a pointer where to find it?

Thanks a lot!

  • 0
    TI__Genius 11081 points

    Hello Heiko,

    The ±45 LSB gain error spec includes temperature variation, and accounts for drift over the expected operating life. We do not publish internal characterization or qualification datalogs, unfortunately, and we do not have a spec for temperature coefficient as this can vary from device to device.

    Best regards,
    Ibukun

  • 0 in reply to Ibukun Olumuyiwa
    Prodigy 20 points

    Hello Ibukun,

    thank you for you quick answer. According to my opinion it would be nice if you could specify the properties of the internal reference separately from the ADC. Then one can directly compare the performance with an external reference as an alternative.

    With your current specification I must use an external reference, although I am sure that this is unnecessary from the technical point of view. It adds additional costs to my design.

    I do understand that company policies are sometimes difficult to understand for us engineers. Therefore I accept your answer and you may close the thread.

    Thank you again for your support

    Heiko

  • 0 in reply to Heiko Gerdes
    TI__Genius 11081 points

    Hello Heiko,

    I understand the predicament. In the future it is possible that we publish a reduced specification that limits the gain error for applications that can limit the operating temp range. The primary driver of the gain error is variation across the -40C to 125C range, and like I said earlier, that curve is not a consistent one across all units, so it is not really practical to specify a tempco equation either. You might get one unit that only varies by 10 LSB and another that changes by 40 LSB. So we really have to live with this spec.

    Best regards,
    Ibukun