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DAC9881: Zero-scale error

Ivy Jin
Expert 3415 points
Part Number: DAC9881

Hi team,

My customer is evaluating DAC9881 in their project.

And they test the Zero-scale error is 13mV, which is larger than the 32LSB on the datasheet.(The REF is 5V).

Could you please help give some comments about the problem?

The customer test the Vout when zero point. Is it possible that the test method of the customer is wrong? Could you please help give some suggestions?
Thank you!
Regards,
Ivy
  • 0
    TI__Mastermind 18996 points

    Hi,

    How are you testing the zero scale error? For this part we specify the zero scale error at 2048 (decimal), not at zero code.

    Please test with 2048 and let me know if this matches with the datasheet specifications. Also measure the reference voltage

    Regards,

    AK

  • 0 in reply to Akhilesh K
    TI__Expert 3415 points

    Hi AK,

    Thanks for your comments.

    May I ask if the zero scale error and offset error is the same parameters, I'm not very sure about it.
    Thanks！
    Regards，
    Ivy
  • +1 in reply to Ivy Jin
    TI__Mastermind 18996 points

    Hi,

    zero code error is also attributed to the output amplifier. It is the error caused by the output amplifier's head room requirements near the positive and negative rails. It is measured by loading all zeros into the DAC data register and observing the difference between the output voltage and the ideal output voltage.

    Offset error describes an offset or shift in the entire transfer function across the linear region of operation. Think of it as the b term in y equals mx plus b.

    Offset error is calculated based on a line of best fit taken from a two-point measurement across the linear region of operation. Typically, somewhere between 10% and 90% full scale range to avoid operating the output of the amplifier in a potentially non-linear region.

    So in the case of DAC9881, datasheet specifies the offset error disguised as zero scale error, not the zero code error.

    Regards,

    AK