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DAC7311 Max Zero-Code Error

Jamaal_Charles
Genius 3245 points
Other Parts Discussed in Thread: DAC7311

I have a customer that would like to know the Max Zero-Code error (page 3 of the datasheet) under normal conditions.  The datasheet shows typical of 0.2mV, but doesn't show max.  There are graphs of zero code error vs. temp for 5V, 2.7V, and 1.8V.  However, they'd like to know the max at 25 C, 5V, so they can compare to competitors parts.  Is that data available?

Thanks,
Eric

  • 0
    TI__Mastermind 43915 points

    Hi Eric,

    The reason that we do not have a max spec is because the zero-code error spec is by design and not verified at final test. I first just want to clarify, are they interested in offset error or zero code error? Offset error is specified as a max value of +/-4mV while zero code error is only a typical value of 0.2mV. Zero code error is going to be a result of the headroom from the rail due to the internal op amp. Therefore, depending on the DAC resolution, reference voltage, LSB size etc. they may have a few codes near ground which read back the same DC voltage (in this case) of about 0.2mV typical. I looked and since this was a typical spec by design rather then test, we do not have any testing data across temperature on zero code error, but my guess would be that temperature would have some small effect.

    Regards,

    Tony Calabria

  • 0 in reply to Tony Calabria
    Genius 3245 points

    Thanks Tony,

    They were wondering about Zero-Code Error first, and your explanation was sufficient.  Now, they want to verify the Full-Scale Error.  I believe the max in the datasheet is over temperature, but they'd like a little more data if possible.  This if for an aerospace application, so they tend to need more data for verification.

    Was there any testing performed for worst case full scale error over temp?  It sounds like this max value might be a theoretical value.  While I see that 0.2% max is considerably better than other DACs on the market, I am a little wary that this part may not have been fully characterized over temperature for worst case.  You say the error is pretty stable – do you have data to confirm that for me?  I have a suspicion that the 0.2% max full scale error listed in the Electrical Characteristics table is at 25°C since the temperature is not explicitly mentioned.  Is this true?

    Thanks,

    Eric

  • 0 in reply to Jamaal_Charles
    TI__Mastermind 43915 points

    Will contact Eric directly.

    Regards,

    Tony

  • 0 in reply to Tony Calabria
    TI__Mastermind 45250 points

    Tony,

    Would there be a histogram available regarding zero code error? I have a customer who is comparing this to the AD5621 which listed the zero code error at a maximum level of 10 mV. We do not list the maximum value, only the typical value. This is why I was thinking that showing them a histogram might help.

    Would the zero code error of the DAC7311 possibly reaCH 10 mV? The histogram might help if it is available.

    Thanks for your help with this!

    Richard Elmquist

  • 0 in reply to Richard Elmquist
    TI__Genius 11750 points

    Hello Richard,

    As Tony suggested in an older post, the max spec parameter is not included in final test  for the DAC7311 device, therefore we may not have data to suggest a max or provide a histogram.  I will check with design and characterization to see if there have been any re-characterization efforts, and if so I will try to find out if data exists for the parameter in question.

    Best Regards,

    Matt

  • 0 in reply to Matthew Sauceda
    TI__Mastermind 45250 points

    Matt,

    Are there any updates on this issue?

    Thanks for your help with this!

    Richard Elmquist

  • 0 in reply to Richard Elmquist
    TI__Mastermind 46290 points

    Richard,

    Matthew is out of office, I will be sure to check with him on Monday.

  • 0 in reply to Kevin Duke
    TI__Genius 11750 points

    Hello Richard,

    After checking with design, I was able to confirm that the max of the specified parameter is not tested in production.

    Best Regards,

    Matt

  • 0 in reply to Matthew Sauceda
    TI__Mastermind 45250 points

    Matt,

    Can you confirm that there is no histogram that we can share with the customer?

    I understand that we do not test this in production, but is there a histogram of the data collected during characterization?

    Thanks for your help with this!

    Richard Elmquist

  • 0 in reply to Richard Elmquist
    TI__Genius 11750 points

    Howdy Richard,

    Min/Max specifications are generally tested in production, while typical parameters are usually studied during characterization.  This may be good to know, as large histograms/graphs can be used when referencing data from production.  Characterization is usually limited to a smaller sample set.  I've checked with characterization to see if such histograms or data exist, but unfortunately they have only the typical values of when the device was characterized.

    Best Regards,

    Matt

  • 0 in reply to Matthew Sauceda
    TI__Mastermind 45250 points

    Matt,

    Thanks for looking. I really appreciate it.

    I will let you know if the customer has any further questions.

    Thanks again.

    Richard Elmquist