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# INA226: current measurement

Part Number: INA226

I am trying to use this IC to measure values from 2uA up to 20 mA. What should be the shunt value? How do I determine the caliberation register value? CAL = 0.00512 / Current_LSB *R_shunt.

How do these values get determined?

• Hi Abhishek,

We have guidelines for choosing a shunt resistor that you could find in this TIPL video: https://www.ti.com/video/6076324596001. As for choosing the CAL register, you would need to know the max expected current to calculate the Current_LSB and then plug that back into the CAL calculation:

Please let me know if you have any further questions!

Best,

Mohamed

• That is the point of confusion I guess. Does this mean that the value of R_shunt is not much relevant as far as I get the CAL register value right?

For my current sense application, I am trying to use INA226  to measure peaks of 10mA. The average current is 5 uA. The absolute maximum current - the in rush current - is 300 mA but I am not interested in monitoring the absolute maximum current.

What should be the values of R_shunt in this case? How do I determine that?

• Hi Abhishek,

The RSHUNT value will still be relevant as it is used to calculate the correct CAL register. You would want to use shunt resistor that maximizes the resolution of the shunt register.

For my current sense application, I am trying to use INA226  to measure peaks of 10mA. The average current is 5 uA. The absolute maximum current - the in rush current - is 300 mA but I am not interested in monitoring the absolute maximum current.

In this case, you could set the max current to10mA, however anything above 10mA will be read as 10mA in the current register. You could theoretically check the shunt register if it exceeds a certain value as long as it doesn't get saturated. We have a tool and app note dedicated to getting started with our digital power monitors that may help:

https://www.ti.com/lit/an/sboa511a/sboa511a.pdf

www.ti.com/.../SBOR021

Best,

Mohamed