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BQ27441-G1: SOC jump at every reboot of micro controller

Abhishek singh
Expert 2000 points
Part Number: BQ27441-G1

Hi Team,

We are using the above-mentioned  part in one of our project, on every reboot,  we are updating 4 parameters ie design capacity, design energy, Terminate voltage and Taper rate without checking ITPOR bit. As per my understanding since these parameters will remain same rewriting them should not impact SOC value But whenever we are rebooting device it shows a jump of approximately 6-8 %. What could be possible reasons, what mistake we are doing?

  • 0
    TI__Guru 61066 points
    This will impact SOC value if you exit with SOFT_RESET because the gauge will take an OCV measurement and resimulate. If the current is not zero then the OCV measurement will not reflect a true OCV, hence the error. Use EXIT_CFGUPDATE instead of SOFT_RESET.
  • 0 in reply to Dominik Hartl11
    Expert 2000 points
    Hi Dominik ,

    Thanks for you quick reply , we are doing the same , we were following section 3.1 of TRM every time which is supposeed to used once only . I will update you about result tomorrow.
  • 0 in reply to Abhishek singh
    Expert 2000 points
    Hi Dominik ,

    Today we checked it is working fine.
  • 0 in reply to Abhishek singh
    Expert 2000 points

    Hi   Dominik,

    We observed that, when we connect the charger to our system and manually RESET our microcontroller, even after doing CONFIG_UPDATE gauge SOC is jumping, we observed that whenever OCVTAKEN bit is getting set, there is a jump in SOC. Please find the attached snapshot of registers.  I was suspecting that may be device is trying to enter into Hibernate mode, before that it is taking OCV.

    Also please not the INITCOMP bit is also getting set. On every manual reboot of the microcontroller.

  • 0 in reply to Abhishek singh
    TI__Guru 61066 points

    There will be an error everytime the gauge takes an OCV measurement with a load current present. Ideally the gauge should not be put in a scenario where it is forced to take an OCV measurement if there is a current present (e.g. reset while the system draws (significant) current, config update with soft reset, ocv command etc.). There is no way to fix this without preventing OCV measurements when the circuit is not open.