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INA220 Measurement Error

na na78
Guru 16770 points
Other Parts Discussed in Thread: INA220

Hi

We have questions about the way of consideration for current shunt measurement errors.
Actually, INA220 has following 3 parameters.

- OFFSET voltage : MAX +- 100uV (PGA=/1)
- Current Sense gain error : +-40m%
- Current Measurement error : +-1% (TA=40 - 85)

1. Does the current measurement error include the offset voltage and the current sense gain error?

In other words, do we have only to consider the current measurement error for the obtained current measurement result?

2. Is the following way of calculation correct?


When the max current = 10A, Rshunt=0.1mOhm, so shunt voltage is 1mV.
Considering the offset voltage, 1mV + 0.1mV = 1.1mV. (There is also 0.9mV)
Considering the current sense gain error, 1.1mV * 1.0004 = 1.10044mV.
Considering the current measurement error, 1.10044mV * 1.01= 1.1114444mV.
We will get the measurement current 1.1114444mV / 0.1mOhm = 11.11444A.
As a result, there is a possibility that we get the measurement error larger than 1A.

regards

  • 0
    TI__Genius 15760 points
    Hi,

    For customers convenience we have created a video training series that focuses on the understanding of the error sources associated with current measurement and the best methods for minimizing these errors. This videos are no more than 6 minutes.

    Please review this. They explain step by step how to calculate the errors and which parameters needs to be considered.
    training.ti.com/getting-started-current-sense-amplifiers


    Regards,
  • 0 in reply to Mayrim Verdejo
    Guru 16770 points
    Hi Mayrim

    Thank you for useful video.
    We understood the impact of gain error and offset error.

    But we couldn't get how to deal the parameter of Current Measurement error.

    What kind of error is the Current measurement error?

    regards
  • 0 in reply to na na78
    TI__Genius 15760 points

    Hi,

    Current Measurement Error is the total error you can expect if you use the conditioned noted on the top page of the Electrical Characteristic. This  number have been tested. Same with Bus Voltage measurement error. You do not need to ADD this number to your calculations. 

    If you do not use those exact conditions then you need to calculate your errors manually following the tutorial I pointed you before. 

    Hope this helps!