Tool/software:
We are using the BQ76925 analog front-end IC for cell voltage monitoring and passive balancing in a lithium battery charger product that supports 3S–6S battery packs. We have successfully implemented the complete circuit as per the datasheet and reference design, and integrated it with a microcontroller that reads scaled cell voltages from the VCx pins.
However, we are encountering inconsistencies in cell voltage accuracy across different PCBs (same design and BOM). The issue is characterized as follows:
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Some PCBs report accurate voltages, while others show deviations of up to ±100 to 200 mV per cell.
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The error is not uniform across all PCBs, and does not follow the IC
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All boards use the same firmware and are tested under the same conditions with the same battery.
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We are using the recommended RC filters on each VCx pin, but suspect layout sensitivity or passive component tolerance might be contributing.