• State
  • Locked Locked
  • Replies 3 replies
  • Subscribers 63 subscribers
  • Views 83 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.

BQ40Z50-R2: SMBus Communication Issue

Manish Dhumal
Prodigy 10 points
Part Number: BQ40Z50-R2
Other Parts Discussed in Thread: BQ40Z50

Tool/software:

We are currently analyzing the SMBus communication waveform of the BQ40Z50-R2 battery management IC. The signals are being directly monitored on the SMBC (clock) and SMBD (data) lines of the BMS.

However, we are observing inconsistent or fluctuating data when attempting to read and display this communication on our device. We would like to understand the potential causes of this fluctuation and whether it may be related to signal integrity, timing mismatches, line capacitance, pull-up resistor values, or any other interfacing issues with the SMBus protocol.

Could you please assist in identifying potential reasons for these anomalies or suggest best practices for reliably capturing SMBus data from the BQ40Z50?

Thank you for your support.

Best regards,
Manish Dhumal.



  • 0
    TI__Guru 61006 points

    It's difficult to say with just this one picture. The signal edges look fairly slow so this may be related to your total bus capacitance and pull-up resistors. The bq40z50 is designed to be compatible with smbus standards and all timing specifications are in the TI datasheet for this gauge.

    We can answer specific questions about the specification in the TI datasheet.

  • 0 in reply to Dominik Hartl11
    Prodigy 10 points

    Thank you for your response.

    We will review the bus capacitance and the values of the pull-up resistors, as you suggested. We'll also refer to the SMBus timing specifications mentioned in the TI datasheet for the BQ40Z50 to ensure compliance. If we encounter any specific points that need clarification, we’ll reach out with detailed questions.

    If there’s any additional data or information you need from our side to help further, please let me know—I’ll provide it if it's available on my end.

    Appreciate your support!

  • 0 in reply to Manish Dhumal
    TI__Guru 61006 points

    From the bq40z50 point of view, I recommend using the lowest pull-up resistor which still allows the gauge to generate a correct logic 0. The datasheet specifies a max. guaranteed voltage for Vol of 0.4V for a current of 1.5mA. I would choose a pull-up resistor that doesn't cause a current in excess of 1.5mA when the gauge drives a logic 0.