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INA226: How to select current LSB and shutdown restor in ina226?

user4838693
Prodigy 190 points
Part Number: INA226

How to select current LSB and shutdown restor in ina226? In my current application, ina226 is used to detect the current of 1.2V (maximum current 2A), but the calculated current is more than 2A, which is quite different from the actual value. Is there a recommended value for the selection of current? LSB and run restor?

  • 0
    TI__Mastermind 27715 points

    Hello User,

    You should select the shunt resistor to maximize input dynamic range for your range of load current. The maximum shunt voltage of the INA226 is  ±81.92 mV. If your maximum load current is 2A, by Ohm's Law the maximum shunt resistor is 81.92 mV / 2A = 40.96 mΩ. 

    The INA226 shunt voltage LSB is not selectable, but rather fixed at 2.5 µV. You can calculate your load current by converting the voltage code from the Shunt Voltage register (01h) back to current, since the shunt resistor is known. 

    Otherwise, if you want to read load current directly from the Current Register (04h), you must first program the INA226 using the steps starting in section 7.6 of the datasheet.

    Best regards,

    Ian Williams
    Applications Manager
    Current Sensing

  • 0 in reply to Ian Williams
    Prodigy 190 points

    Hi,

    yes,voltage LSB is not selectable,but current LSB is calculated by formula 2 .And the maximum shunt voltage of the INA226 is  ±81.92 mV，do I have to choose the maximum value to calculate the resistance?

  • 0 in reply to user4838693
    TI__Mastermind 27715 points

    Hello User,

    You do not have to use the maximum resistance, it just tells you the upper limit. In this case, any resistance ≤ 40.96 mΩ will work. However, lower resistance will mean lower input voltage, meaning offset-related errors will increase. On the other hand, using higher resistance will increase power dissipation across the shunt. It's a compromise you must decide based on your application requirements.

    Best regards,

    Ian Williams

  • 0 in reply to Ian Williams
    TI__Mastermind 27715 points

    Hi User,

    It's been some time since your last post. I hope your issue has been resolved. If you need more help, please reply with the answers to our questions and we are happy to help with your troubleshooting.

    Best regards,

    Ian Williams
    Applications Manager
    Current Sensing