BMS Current Measurement

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BMS Current Measurement

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Mohit_mcu
Contributor I

I am using NXP RD33771-48VEVM BMS evaluation board. I have a issue with reading the current of pack from shunt resistor present in the board. According to the reference document UM11300, I have used the resolutions for calculating the stack voltage, each cell voltage. I thought that for current measurement same ANx resolution will work. But, unfortunately values are not coming proper. 

Please help me with this issue.

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TomasVaverka
NXP TechSupport
NXP TechSupport

Hello Mohit,

As stated in the MC33771 datasheet, the resolution of the current sense register is 0.6uV/LSB.
This results in 6mA/LSB when using a 100uΩ shunt resistor on the RD33771-48VEVM.
Here is the complete explanation and example:

image (1).png

BRs, Tomas

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Mohit_mcu
Contributor I

Yes it resolved my problem.

 

Thanks.

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