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INA219: Current Calibration

Kai Hsiao
Guru 12675 points

Part Number: INA219

Hi Sir 

I saw datasheet example to calculator Current_LSB and result is 457uA/bit 

Datasheet round up to 1mA/bit to do 

If my calculate result is 79uA/bit ,I need to use 1mA/bit or 0.1mA/bit to do?

Thanks

  • 0
    TI__Genius 15770 points

    Hi Kai,

    Allow me sometime for review so I can provide a recommendation.

    Regards

  • 0
    TI__Genius 15770 points

    Hi Kai,

    Please use 100uA (0.1mA) for simplicity and highest resolution. 

    The highest resolution for the Current Register (04h) can be obtained by using the smallest allowable Current_LSB based on the maximum expected current (in your case 79.34uA). While this value yields the highest resolution, it is common to select a value for the Current_LSB to the nearest round number above this value (100uA (0.1mA))  to simplify the conversion of the Current Register (04h) and Power Register (03h) to amperes and watts respectively. 

    Regards

  • 0 in reply to Mayrim Verdejo
    Guru 12675 points

    Hi Mayrim 

    Thanks for your reply 

    You can see when I use 0.1mA/bit and 1mohm to calculate ,the calibration value is 64000 (hex) 

    64000 = 0110 0100 0000 0000 0000 is over 16bit register (05H)

    So I need to modify Rshunt from 1mohm to 10mohm ,am I right ??

    or you have any suggestion ?

  • 0 in reply to Kai Hsiao
    TI__Genius 15770 points
    Hi Kai,

    Yes! That would work. I indeed verify the out of range in the evaluation board with the lower resistance. Using 10m ohm will work. You can keep the 0.1mA/bit.