BQ34Z100-G1: Current sense resistor value

Shreya Agrawal

Part Number: BQ34Z100-G1

Hi team,

I am working on a 131V battery pack with a max current output capability of 80A. I used a 2mohm sense resistor and for the load drawing 5A (tried to calibrate current keeping 5A max current output as of now, and hence gave no scaling factor), the current reported by the gauge is around 60A. Kindly tell me if the resistor value is too small and that we need an opamp or am I missing any calibration step.

I calibrated CCGAIN, CCOFFSET, BOARD OFFSET followed by current.

Thanks,

Shreya

over 2 years ago

0 Shirish over 2 years ago

TI__Guru 57697 points

Hello Shreya,

The lowest value acceptable is 5mOhm. Below this value, the noise is high and will result in degradation of accuracy.

0 Shreya Agrawal over 2 years ago in reply to Shirish

Prodigy 240 points

Hi Shirish,

I will change the value to something above 5mohm and then test it for 5A; will the 2mohm resistor give partially accurate values if I increase the load current, like passing 20A instead of 5A.

0 Shirish over 2 years ago in reply to Shreya Agrawal

TI__Guru 57697 points

Hello Shreya,

The 2mohm may work for higher currents but the gauge has not been characterized for such a low value, so we cannot say for sure

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BQ34Z100-G1: Current sense resistor value