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BQ40Z80: Unexpected reset

Theodore Beauchant
Prodigy 105 points
Part Number: BQ40Z80

Tool/software:

Hi Folks,

We are having an issue with the BQ40Z80 which seems to perform unexpected resets every now and then. This happens while the battery is in discharge, usually at high amps but not always (20A/30A) communications stops with the BMS for 2 to 3 seconds before coming back.

When it comes back all values seems correct (voltage, current, ...) however the remaining capacity has jumped by 10 to 20% relative to its original value. I imagine that this is because on reset the chip performs a voltage reading to establish the current battery capacity, and since this is on a rather heavy load the voltage is not accurate.

How could we go around fixing this? Are there known issues or phenomenons that could explain those resets?

Just in case this can be useful: These battery are used in a redundant scheme (two batteries) connected through ideal diode circuits using the LTC4359. They drive a brushless motor that goes around 60A at max. The BQ40 is connected to an STM32 MCU for reading through the smbus.

Many thanks,

  • 0
    TI__Mastermind 26395 points

    Hello Theodore,

    This question has been assigned and will be reviewed when possible.

    Thank you,
    Alan

  • 0 in reply to Alan Frias
    Prodigy 105 points

    Hi,

    Any news on the topic?

    Thanks

  • 0 in reply to Theodore Beauchant
    TI__Mastermind 28470 points

    Hi Theodore,

    Is it possible to share a log file from during this period when the resets occur? Also, can you please turn on the lifetime tracking (LT_EN command) so we can look at the values in the gg file after the resets have occurred?

    Regards,

    Anthony

  • 0
    Prodigy 40 points

    Hello, we are running into a similar issue. we are trying to implement something that addresses this other post: e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1336537/bq40z80-device-resets-after-smbus-communication?tisearch=e2e-sitesearch&keymatch=i2c%2525252520reset%2525252520bq40z80#

    maybe this would be hlepful to you

  • 0
    Prodigy 105 points

    Hi Anthony,

    Thanks for your reply. Could you specify which data you would like to see in the log during the event?

    This is in a UAV application and so far has only happened in flight, so we can't keep the BQ programmer connected to monitor the event and will have to edit our MCU code to log the required data.

    @Jonathan: Thanks for the link, we had found it earlier and were in the same situation (we were polling at 10ms interval), we have implemented the change to 100ms but this did not have any impact.

    Thanks,

    Theo

  • 0
    Prodigy 105 points

    Hi Anthony,

    Thanks for your reply. Could you specify which data you would like to see in the log during the event?

    This is in a UAV application and so far has only happened in flight, so we can't keep the BQ programmer connected to monitor the event and will have to edit our MCU code to log the required data.

    @Jonathan: Thanks for the link, we had found it earlier and were in the same situation (we were polling at 10ms interval), we have implemented the change to 100ms but this did not have any impact.

    Thanks,

    Theo

  • 0 in reply to Theodore Beauchant
    TI__Mastermind 26395 points

    Hello,

    We have received your update and will follow back with a message within the week.

    Thank you,
    Alan