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BQ76952: Cell balancing/ COV/ CUV

sungjun Heo
Prodigy 20 points
Part Number: BQ76952

TI Team.

I have a question about Bq76952 Cell balancing logic.

I know that when cell balancing operates, COV/CUV diagnosis is performed at 1sec intervals.
I have a few questions for you here.

1. Can COV/CUV diagnosis be disabled during CB operation?
ex) Enable Protections A - COV Disable...


2. Is there a way for the host to know that COV/CUV diagnosis is running during CB operation?
ex) Alert pin Trigger

Please respond in detail.

  • 0
    TI__Mastermind 42060 points

    Hello Sungjun,

    The COV/CUV check will not be disabled, even if the protections are disabled in the registers.

    No, the COV/CUV will not alert anything unless a OV/UV condition is met or the OV/UV protection triggers. Which would depend on the the ALERT pin settings and the protection settings.

    Best Regards,

    Luis Hernandez Salomon

  • 0 in reply to Luis H. S.
    Prodigy 20 points

    Thanks for your reply.

    I want the MCU to know that I'm doing COV/CUV verification.
    Can you give me some ideas on how the MCU can figure this out?

  • 0 in reply to sungjun Heo
    TI__Mastermind 42060 points

    Hello Sungjun,

    For this check in particular, there is really no way to tell the MCU that it is happening. This is only really visible during cell balancing and it happens with a period of 1-second.

    Best Regards,

    Luis Hernandez Salomon

  • 0 in reply to Luis H. S.
    Prodigy 20 points

    Hi Luis.H. S.

    thank you for your reply.

    I am curious about the timing of recognizing the Bq76952 Host's command request and the timing of performing COV and CUV diagnosis.

    So, I ask the question below.

    1. Is the Cell balance Interval setting related to the time it takes to recognize a host command?

    2. Are the time to determine the cell balancing algorithm and the timing (internal timer) to perform COV and CUV diagnosis the same?

    3. What is the error in the interval (about 1sec) at which COV and CUV diagnosis is performed every 1sec?

    4. Is there any data (waveforms) from a balancing test on multiple Cell channels simultaneously?

    I would like to know the timing when CB stops due to COV and CUV for each channel.

  • 0 in reply to sungjun Heo
    TI__Mastermind 42060 points

    Hello Sungjun,

    sungjun Heo said:
    1. Is the Cell balance Interval setting related to the time it takes to recognize a host command?

    No.

    sungjun Heo said:
    2. Are the time to determine the cell balancing algorithm and the timing (internal timer) to perform COV and CUV diagnosis the same?

    COV/CUV check runs in a separate timer to the cell balancing algorithm. They run asynchronous from each other. Details on this error is explained in Section 2.5 Voltage Measurement Accuracy During Balance of the Cell Balancing With BQ769x2 Battery Monitors application note.

    sungjun Heo said:
    3. What is the error in the interval (about 1sec) at which COV and CUV diagnosis is performed every 1sec?

    It is hard to say, as it would depend on when the part is taking the measurement vs. what is the voltage change due to the COV/CUV check.

    sungjun Heo said:
    4. Is there any data (waveforms) from a balancing test on multiple Cell channels simultaneously?

    What specifically would you like here? We have cell balancing waveforms in the application note I shared above. 

    sungjun Heo said:
    I would like to know the timing when CB stops due to COV and CUV for each channel.

    Around 20-ms.

    Best Regards,

    Luis Hernandez Salomon