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INA226: MSB bit of Calibration Register (05h)

Ramesh Dasari
Prodigy 50 points
Part Number: INA226
Other Parts Discussed in Thread: INA238, , INA228, SYSCONFIG

Hi,

According to spec document,the MSB bit of the calibration register can't be written.I have attached the screenshpt for your reference.

Is there any chance we can write the MSB bit of the calibration register?

If there is any chance let us know how to write it?

  • +1
    TI__Mastermind 27015 points

    Hello Ramesh,

    Thank you for using the TI forum.  This bit cannot be written, the calibration value itself can only be 15 bits of data. If your calibration value is too high, you need to either increase the shunt value, or raise the Current_LSB.

    One common cause of wanting a higher calibration value than this device can take is from using a very small Current_LSB. In my experience, this is usually smaller than the INA226 can accurately measure. In this case, you may want to consider switching to our newer line of digital current shunt monitors (Specifically INA228 and INA238 as they are pin compatible with the INA226. The INA238 has comparable accuracy/price with the INA226, while the IINA228 is higher end and can accurately measure very small currents).  While these devices also use 15 bits for the calibration register, they have a wider input sense range and lower lower input bias current (plus extra features), that may work out better for you than the INA226.

    If you do decide to switch devices, you can use SysConfig to help with the needed software changes: https://dev.ti.com/sysconfig/index.html?product=ascstudio