• State
  • Locked Locked
  • Replies 3 replies
  • Subscribers 63 subscribers
  • Views 371 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Original question:

BQ40Z50-R2: Exit shutdown goes in ROM Mode when temperature is 7-9°C

BQ40Z50-R2: Undocumented methods of entry into BootROM when in full access mode

Leo Hock-Morris
Prodigy 20 points
Part Number: BQ40Z50-R2
Other Parts Discussed in Thread: BQ40Z50

Tool/software:

I am currently working with the BQ40Z50-R2 and have encountered an issue where the batteries have randomly stopped responding to I2C communication. Alongside this, the charge and discharge FETs turned off, resulting in no voltage at the pack pins. Initially, the only way we found to fix this was by power cycling the device.

 

Upon researching, I found a related forum post where it was suggested that there are undocumented ways the chip can enter BootROM mode when it is not sealed. This behaviour might be causing our issue, specifically sending the shutdown command when the temperature is low. We have been unable to recreate the issue on the bench, but it seems to occur in a car overnight, possibly reaching these colder temperatures. I have managed to get the batteries out of this state by sending the exit ROM mode command, confirming the issue.

 

Could anyone provide more detailed information on these undocumented methods of entry into BootROM when the chip is in full access mode? We hope to gain some more insight on these methods and how to prevent them in the future for devices still in full access mode.

 

Thanks!

  • 0
    TI__Mastermind 37761 points

    Hey Leo,

    When using the BQ40z50 in the final application, is the gauge in unsealed mode or full access mode?

    If the gauge is unsealed when used in the field, there will be unexpected behaviors. We always recommend to have the gauge sealed when used in the field.

    Regards,

    Nick Richards

  • 0 in reply to Adrian
    Prodigy 20 points

    Hey Nick,

    We believe the gauge is in full access mode. And although that may be the main cause, we are looking at ways to re-create our issue, and wanted to understand the potential side effects and other issues that may occur.

    What are the main differences between full access, unsealed and sealed that you might be concerned about?

  • 0 in reply to Leo Hock-Morris
    TI__Mastermind 37761 points

    Hey Leo,

    I do not know of definitive ways to replicate this when the gauge is unsealed. 

    The main difference is when the gauge is in full access mode, the gauge can be sent to ROM mode and update authentication keys, and update data memory. When the gauge is unsealed, then it is only able to update data memory.

    Regards,

    Nick Richards