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[ DAC121S101-Q1 ] about TUE(Total Unadjusted Error) Calculation

Paul Kim
Intellectual 1430 points
Other Parts Discussed in Thread: DAC121S101-Q1

hi team

may I get your reply to the below two questions ?

thanks.

[Q1] for DAC121S101-Q1, if using 12 bits resolution with Va = 5V,

       i calculate Max TUE = 42 LSB as below. am I right ?

      ( because customer want to see Max TUE..)

- Max OffsetError = 15mV x 4096 / 5000mV = 12 LSB,

- Max Gain Error = 1% / 100 x 4096 = 40 LSB

- Max INLError = 8 LSB,

  therefore, Max TUE = Sqrt( 12^2 + 40^2 + 8^2 ) = 42 LSB 

[Q2] the following calibration way to remove OffsetError and GainError in TUE can be also used for DAC121S101-Q1 ?

  • 0
    TI__Genius 16410 points
    Hello Paul,

    Let me move this to the precision data converters, they should be able to answer your question.

    Regards,
    Karl
  • 0 in reply to Karl Wallinger
    TI__Genius 16890 points

    Hello Paul,

    The formula also should include DNL, but since the DNL spec is only 1LSB it doesn't change your calculation.

    To calibrate out offset and gain error you need to make two measurements of known points.  The first measurement determines that value that needs to be subtracted from the samples.  Using both samples you can determine the actual gain and use that to modify your samples.

    Mike

  • 0 in reply to Michael Stout
    TI__Intellectual 1430 points

    Hi Michael

    D/S say INL with the decimal code range of 48 ~ 4047.

    for two points measurement for offset and gain calibration,

    i think we should use two points to be picked up from 48 ~ 4047.

    - may I use two points below 47 and above 4048 ?

    - my think is the best two points are using the boundary of INL range; DAC = 48 for (X1,Y1) and DAC = 4047. what is your view on my thought ? 

  • 0 in reply to Paul Kim
    TI__Genius 16890 points
    Hello Paul,

    I think it would be best to pick the two points between 48 to 4047 as you suggest. This is the range that the device is specified so it would be best to stay in this range.

    Mike