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INA169: Accuracy of INA169 amplifier for 1mA to 4A current range

Meenalochini D
Prodigy 150 points
Part Number: INA169

Hi ,

We have a requirement of measuring 1mA to 4A current with 1mA accuracy.

What will be the INA169 amplifier Gain/output error voltage for these current range?

What are the parameters to be checked to get the accuracy and error parameters which can't be calibrated.

Regards,

D.Meenalochini.

  • 0
    Prodigy 150 points

    Hi Team,

    Adding few more inputs.

    Common mode voltage =40V,

    Rsense=25mohm

    RL=24Kohm

    Please share the excel based error budget analysis sheet if possible.

    Regards,

    D.Meenalochini

  • 0 in reply to Meenalochini D
    TI__Mastermind 27380 points

    Hi,

    Please see attached Excel sheet showing total error analysis for the given condition, and current ranging from 1mA to 4A.

    Total_Error_vs_Sensedcurrent (4).csv

    This data is generated by the online calculator, and can be easily updated should the condition change. Please give the calculator a try, and here is the how the interface looks:

    Regards, Guang

  • 0 in reply to Guang Zhou
    Prodigy 150 points

    Hi  Guang,

    I can see the huge error on the graph in lower current range.

    Assumed Offset error can be calibrated in No-load condition and Error due to Rsense & RL tolerance can be calibrated in Known-load condition.

    Only non-linearity error and total output error will be non-calibrated.

    Please confirm whether my understanding is right?

    If so ,how do we calculate those non-calibrated error.

    Request your support on this.

    If possible,arrange the webex session.

  • 0 in reply to Meenalochini D
    Guru 140200 points

    Hi,

    the input offset error voltage of INA169 is up to +/-1mV. This is 40 times bigger than your minimum input voltage across the shunt of 25µV. Therefore, with your 25mR shunt 1mA cannot be measured without huge error.

    This huge error cannot be calibrated out. An input offset error voltage in the same order of the minimum input voltage of 25µV or preferably much lower could be calibrated out. But not an input offset error voltage which is 40 times bigger than 25µA. Keep in mind that the input offset error voltage not only varies with temperature but also with common mode input voltage and power supply voltage. And even more, it also shows a long term drift.   

    Kai

  • 0 in reply to kai klaas69
    Prodigy 150 points

    Hi Guang/Kai,

    Thank you for your detailed reply.

    Regards,

    D.Meenalochini.