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BQ76942: BQ76942 Program issue

YUXUAN CHIANG
Prodigy 225 points

Part Number: BQ76942
Other Parts Discussed in Thread: EV2400

Hi TI Teams,

Hello, I’m Steve from Dediprog RD team.
I had previously consulted with you regarding the programming support for the BQ76942.
I would like to check if it’s convenient for you to assist me with another related question.

One of our customers is currently experiencing programming failures.
From my analysis, it appears that the defective ICs encounter I²C communication issues approximately one second after power-up.
However, within the first second after power-up, the IC can communicate normally.
This behavior is consistent whether we use our programmer or the EV2400.

May I ask how this issue can be resolved?
The attached image shows our current hardware circuit design.

image (1).png

Thanks.

Steve.

  • 0
    Prodigy 225 points

    Hi TI Teams,

    Is anyone able to help me resolve the programming issue?

    Thank you.

    Steve.

  • 0
    Prodigy 225 points

    Hi TI Teams,

    Is anyone able to help me resolve the programming issue?

    Thank you.

    Steve.

  • 0
    Prodigy 225 points

    Hi TI Teams,

    Is anyone able to help me resolve the programming issue?

    Thank you.

    Steve.

  • 0
    Intellectual 280 points

    Hi TI partner,

    May i know any update or suggestions?

    Our customer is waiting for our update and solution.

    Thanks.

    Jack

  • 0
    Intellectual 280 points

    Hi TI partner,

    May i know any update or suggestions?

    Our customer is waiting for our update and solution.

    Thanks.

    Jack

  • 0
    Prodigy 225 points

    Hi TI Teams,

    Is anyone able to help me resolve the programming issue?

    Thank you.

    Steve.

  • 0 in reply to YUXUAN CHIANG
    TI__Mastermind 22845 points

    Hello Jack and Steve,

    I have the following questions:

    1. What is HDQ being used here for? I see it's also powered by the 3.3V.

    YUXUAN CHIANG said:
    From my analysis, it appears that the defective ICs encounter I²C communication issues approximately one second after power-up.
    However, within the first second after power-up, the IC can communicate normally.
    This behavior is consistent whether we use our programmer or the EV2400.

    2. Is the SCL/SDA lines being powered from our device's REG1 lines or externally? When you say communication issues, is this referring to the device NACKing or something else? Do you have any logic analyzer files showing this as well as any waveforms?

    If using our device's REG1 line, it may take some time for the device to power up the REG1 and then accept communication. Table 16-2. Startup Sequence and Timing from our datasheet shows some of the timings when our device starts up. 

    Best Regards,
    Alexis

  • 0 in reply to Alexis_H
    Prodigy 225 points

    Hi Alexis,

    1. The HDQ pin is only a reserved pin. It was kept initially in case it might be needed in the future, but it was later determined that this pin would not be used.


    2. SCL/SDA share the same power supply as the IC. The communication issue is that communication works within the first second after the IC is powered on, but once more than one second has passed after power-up, the IC always responds with NACK.


    At the time of testing, we only observed this behavior and did not record it in detail. We will need to set up the test environment again to verify this.

    Thanks.

    Steve.

  • 0 in reply to YUXUAN CHIANG
    TI__Mastermind 22845 points

    Hello Steve,

    YUXUAN CHIANG said:
    1. The HDQ pin is only a reserved pin. It was kept initially in case it might be needed in the future, but it was later determined that this pin would not be used.

    Thanks for clarifying. If the HDQ pin is going to pin unused, it can either be left floating or connected to VSS.

    YUXUAN CHIANG said:
    2. SCL/SDA share the same power supply as the IC. The communication issue is that communication works within the first second after the IC is powered on, but once more than one second has passed after power-up, the IC always responds with NACK.

    So the communication line is powered externally, not through the device's LDO pins. Are you determining the time the device powers-up by measuring it from the BAT pin or from when the REG18 pin shows 1.8V as well? 

    If you are able to share any further details after setting up the test environment, please let me know.

    Best Regards,
    Alexis