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ADS8860: Hi, I have a question about offset error calculation.

Yunsik Chung
Intellectual 1150 points
Part Number: ADS8860

Hi, i was studying about calculating offset error in ADC system with TI precision LAB.

I can understand the concept of using typical offset error when we calculate the total error.

However, I cannot understand the equation of total offset error using squre and root.

Could you explain in more detail why we use this equation when we calculate with typical value?

Thanks,

Yun

  • 0
    TI__Mastermind 40860 points

    Hello Yun,

    This type of addition is referred to as RSS, or Root,Sum,Squared.  It is a statistical method commonly used when adding normally distributed numbers.  There is a lot of information that you can search on the web that goes into more detail on why this method is used.

    In the above TI Precision Labs example, we could have simply added all of the errors, but this would have give an unrealistically high estimation for the total error.  The typical number is 1 sigma, but this implies that 68% of all devices are better than the typical!  If you have several components adding to the overall error, it is unlikely all devices will be near the 1 sigma value, many will be much lower. 

    Regards,
    Keith Nicholas
    Precision ADC Applications 

  • 0 in reply to Keith Nicholas
    TI__Intellectual 1150 points

    Hello Keith,

    Thank you very much!

    Yun