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INA233: Datasheet - Shunt Input Offset Voltage vs Temperature figure

David Eisele
Prodigy 20 points

Part Number: INA233

Hi,

for the shunt measurements the VOS vs temperature is stated as typ. 0.02 µV/°C (max. 0.1) in the in the Electrical Characteristics, but Fig. 3 shows only a flat line of "0µV" over the whole temperature range.
I guess there was an error generating the Figure in the datasheet, or did I misunderstood something in the El.Ch. table (e.g. at 125°C the typ./max. offset error would be ~2 µV/10 µV, resp.)?

Best regards
David

  • 0
    TI__Mastermind 32395 points

    Hey David,

    Thanks for bringing this to the forum. The VOS vs temperature plot in the datasheet may very well contain an error in scaling (I will look into this), but overall it should not change predicting the error of the device.

    The datasheet data plots are not meant to show worst-case behavior, but typical or nominal behavior. The Electrical Characteristics table is meant to show the worst-case maximum and minimum specifications so in the end always refer to these values when determining theoretical error.

    It is important to note that input offset drifts can go in positive or negative direction and that the initial input offset spec of +-2uV to +-10V is at 25 degrees Celsius. This means that the maximum theoretical input offset at 125C is 10uV + 0.1uV/C*(125C-25) = 20uV.

    Hope this helps.

    Best,

    Peter Iliya

     

  • 0
    TI__Mastermind 32395 points

    Hey David,

    I am still working on confirming the data, but Figure 3 is very possible if the offset is within +-1 LSB where LSB = 2.5uV.

    So if the true offset changes from -2.4uV to +2.4uV over -25C to 140C, then the device's internal ADC will report 0uV. In this scenario, the offset drift equals 2.8uV/165C = 0.029uV/C which is right around the typical drift of the device.

    Sincerely,

    Peter

  • 0 in reply to Peter Iliya
    TI__Mastermind 32395 points

    Hey David,

    After investigating with my team, the Figure 3 of INA233 datasheet is correct and shows data from a single DUT.

    Sincerely,

    Peter Iliya

    Current Sensing Applications

  • 0 in reply to Peter Iliya
    Prodigy 20 points

    Hey Peter,

    ok, I understand now. Thanks for your effort and helpful explanation!

    Best regards,

    David