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BQ27Z561-R2: Discrepancy in current calibration during Learning Cycle with BQ27Z561

Ruchika Bagal
Prodigy 20 points
Part Number: BQ27Z561-R2
Other Parts Discussed in Thread: BQ27Z561, BQSTUDIO

Tool/software:

Hi,

I am currently implementing the learning cycle using the BQ27Z561 fuel gauge IC on an LP353035 LiPo battery (3.7V, 400mAh). However, I am encountering discrepancies in the current values during calibration.

For instance, when I discharge the battery and calibrate the current to -1A, the discharge proceeds correctly. But when I charge the battery the power supply device shows 181mA, while bqStudio reports 202mA.

Could you explain why this discrepancy occurs and suggest how to calibrate the system to ensure the current values on both the load device and bqStudio match accurately?

Thanks,

Ruchika

  • 0
    TI__Mastermind 18181 points

    Hello Ruchika, 

    Have you followed the current calibration procedure outlined in section 12.2 Current Calibration from the BQ27z561-R2 TRM? 

    Regards, 

    Jonny. 

  • 0 in reply to Robert
    Prodigy 20 points

    Hi, 

    Yes, I went through the procedure given in the TRM, but those steps are done manually. I want to calibrate current directly through bqstudio from the calibration section. How can I do that?

    Thanks,

    Ruchika

  • 0 in reply to Ruchika Bagal
    TI__Mastermind 18181 points

    Hello Ruchika, 

    You should be able to follow the procedure in the BQ27z558EVM User's Guide. The BQ27z558EVM and the BQ27z561EVM are very similar to one another. 

    Regards, 

    Jonny. 

  • 0 in reply to Robert
    Prodigy 20 points

    Hi,

    I have completed my Learning Cycle, and now, while testing the Golden Image with the custom board, I am experiencing sudden jumps whenever the battery gets fully discharged or fully charged. The jumps are occurring only with the custom board and not with the EVK. Even, the full charge capacity of the battery is also reducing every time a charging/discharging happens.

    Can you suggest something over this? I am unable to determine the exact reason for these jumps and the decrease in the battery capacity. Additionally, during the Ra table update, only Ra_0 was updated, and not R_a0x. Should both tables be updated for a successful implementation of the learning cycle?

    I am attaching the Golden file and the log files for both charging and discharging for your reference. Please review them and let me know what might be causing this issue.

    5342.Log Files.zip17-06GoldenImage.zip

    Thanks,
    Ruchika

  • 0 in reply to Ruchika Bagal
    TI__Mastermind 18181 points

    Hello Ruchika, 

    This is odd, could you please send me the schematic of your custom board? 

    Additionally it is fine that only Ra_0 updated. 

    Regards, 

    Jonny. 

  • 0 in reply to Robert
    Prodigy 20 points

    Hi,

    Sure! I am attaching the schematic below.

    Thanks,

    Ruchika

  • 0 in reply to Ruchika Bagal
    TI__Mastermind 18181 points

    Hey Ruchika, 

    I do not see any obvious issues with the schematic. The fact that you are only seeing this off behavior on your custom board and not the EVM though leads me to believe that the issue resides in your custom board. Are you sure you have carried out the same procedure as with the EVM, and you are using the same golden image? 

    Regards, 

    Jonny. 

  • 0 in reply to Robert
    Prodigy 20 points

    Hi,

    Yes, the same procedure has been followed and the same golden image has been programmed on the custom board as with the EVM, still this issue persists.

    Thanks,

    Ruchika

  • 0 in reply to Ruchika Bagal
    TI__Mastermind 18181 points

    Hello Ruchika, 

    It seems like the cause of the behavior is with your custom board as this behavior does not translate over to the EVM. Additionally, can you send over bqStudio log files of this behavior? The log files you send over do not give enough information. 

    Regards, 

    Jonny.