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INA700: low current accuracy

Ohad Bonneh
Intellectual 2650 points

Part Number: INA700

Tool/software:

Hi Team, 

when dealing with very low currents, 

what will be the accuracy of the INA7xx family? 

i am having currents at about 30mOhm up to 500mOhm and the voltage rail is 24V 

what would be the accuracy i can get from this device? 

  • 0
    TI__Mastermind 30515 points

    Hello Ohad,

    I will presume you meant mA for units above, instead of mΩ. That will depend a lot on your conversion and averaging settings. I recommend looking over the ENOB table to see the effective number of noise free bits you will have based on your allowable system settings. You will also want to look at the gain errors and offset errors and see if they are within your tolerances (or if you would need to calibrate). In general, that is a very small current compared to the full sensing range of the INA700, and you would be better off using a different device with a custom shunt value to maximize your accuracy and resolution. 

    Regards,

    Mitch

  • 0 in reply to Mitch M
    TI__Intellectual 2650 points

    ohh sure haha 30mA - 500mA, 

    We can endure even 5% accuracy but i am worried that we cannot even achieve that.. 

    any thoughts? 

  • 0 in reply to Ohad Bonneh
    TI__Mastermind 30515 points

    Hey Ohad, 

    That may depend on the amount of calibration you are willing to do. The maximum current offset is ±1.5mA, which is 5% of 30mA. So the offset alone would be too much error for you at the low end. However, you can calibrate the offset current out, which would help significantly. Then you would be more limited by ENOB and gain error. Gain error can also be calibrated out, even across temperature if required. However, it that can be a lot of calibration, and it may be easier to pick a device that works better for your system.

    Regards,

    Mitch