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BQ76940: SDA and SCL lines were not PULLING UP

AJITH KUMAR
Intellectual 510 points
Part Number: BQ76940

Tool/software:

Hi TI Team,

DRONE BMS.pdf

Please find the attached schematic. We have a custom BMS board. Initially, the SCL and SDA lines were not pulling up. On resistors R103 and R104, one side was getting 3.3V, but the other side was showing 0.8V. The other end of the resistors is directly connected to the BQ76940 IC, so we suspected that the IC was pulling the pin low. To confirm this, we lifted the SDA pin of the IC from the PCB, but the SDA pin was still not being pulled high. Kindly guide us on what needs to be checked.

Thanks and Regards,

A. Ajith Kumar

  • 0
    TI__Mastermind 42060 points

    Hello Ajith,

    Is the MCU pulling these pins low? 

    Have you disconnected SDA and SCL separately to see if either one would be able to pull-up without the other?

    Additionally, have you attempted putting external pull-up resistors with an external power supply?

    Best Regards,

    Luis Hernandez Salomon