BQ76907: Cell Voltage Accuracy / Resolution

Max Nemer

Part Number: BQ76907

Tool/software:

Hello,

In the bq76907 datasheet, table 6.12 specifies cell voltage accuracy. I see entries with variations in input voltage range as well as temperature. I am curious if we know what conversion speed these values represent? I would expect that accuracy degrades the faster the converter is run. Are these accuracy values representative of the converter running at full resolution in "SLOW" mode?

If I was to run the converter at faster speeds with lower "effective" resolution (say MEDFAST) we still get 16 bit output codes at 1mV resolution, correct? Would I just plan to ignore the 2 LSB of the 16 bit output codes and effectively now have 8mV resolution with 14 bits?

Best Regards,

Max Nemer

2 months ago

0 Maxwell Verboncoeur 2 months ago

TI__Mastermind 24330 points

Hi Max,

Max Nemer said:
If I was to run the converter at faster speeds with lower "effective" resolution (say MEDFAST) we still get 16 bit output codes at 1mV resolution, correct? Would I just plan to ignore the 2 LSB of the 16 bit output codes and effectively now have 8mV resolution with 14 bits?

Correct. The "effective resolution" is reduced as the conversion speed increases. The change in effective resolution with higher speeds could also be seen as a change in the accuracy, you can see the definition of effective resolution here:

Regards,

Max Verboncoeur

0 Max Nemer 2 months ago in reply to Maxwell Verboncoeur

Prodigy 40 points

Thank you Max. Do you know what speed/resolution the converter was running at to generate the accuracy values in table 6.12?

0 Maxwell Verboncoeur 2 months ago in reply to Max Nemer

TI__Mastermind 24330 points

Hi Max,

It would have been running at the default speed (SLOW mode / 16-bit).

Regards,

Max Verboncoeur

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BQ76907: Cell Voltage Accuracy / Resolution