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Original question:

BQ25620: VSYS falls to low after few minutes.

BQ25622E: VSYS falls to 2V when powered by battery

Ariel Burman
Prodigy 10 points
Part Number: BQ25622E


Tool/software:

We have an application where the system voltage falls suddenly to 2V for 160 ms.

We have seen this behavior only when powered by battery, if we plug a power source to VBUS we don't see this behaviour.

We are disabling the watchdog so we have the IC working in Host Mode.

We don't see any interruption from the PP.

We have observed this issue with battery fully charged, middle charge, and low charge, so we don't think is related to battery voltage.

Here BQ25620: VSYS falls to low after few minutes. it is mentioned a very similar situation and it was mentioned that there is a known issue and a workaround so I'll be very grateful if anyone can share the workaround with us.

  • 0
    TI__Mastermind 32110 points

    Hello Ariel, 

    Thank you for reaching our via E2E. 

    What I2C mode (i.e. clock frequency) are you using in your system? 

    Best Regards,

    Garrett

  • 0 in reply to Garrett Kreger
    Prodigy 10 points

    We are using 400 kHz.

    We started exploring 100 kHz today and have not seeing this issue for the moment, but 400 kHz would be preferable.

  • 0 in reply to Garrett Kreger
    Prodigy 10 points

    With 100 kHz we don't see the issue, so it is only with 400 kHz

  • +1 in reply to Ariel Burman
    TI__Mastermind 32110 points

    Hi Ariel, 

    Thank you for the confirmation of the I2C clock frequency you are using in your testing. 

    Please allow me to refer you to section 8.5.1 Serial Interface in the BQ25622E datasheet. There is a requirement related to I2C communication when using the BQ25622E. 

    When in battery only operation if the I2C requirement is not met the BATFET turn off behavior you observe can occur. The simplest adjustment is to use 100kHz.

    Additionally, we are currently in the process of releasing a new revision of the datasheet where timing requirements are relaxed compared to the overly conservative requirements listed in the current revision. Therefore please refer to the timing requirements shown below. 

    Best Regards,

    Garrett