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BQ40Z50: Clarification on BQ40Z50 Communication Timing and SHUT DOWN MODE Exit Conditions

Tom Tsao
Expert 1870 points
Part Number: BQ40Z50
Other Parts Discussed in Thread: EV2400

Tool/software:

Dear TI Support Team,

I am currently working with the BQ40Z50 fuel gauge and would appreciate your assistance in clarifying two questions:

  1. Command Reception Timing: When sending commands to the BQ40Z50 through the EV2400, how long does it take for the device to receive and process the command? Is there a specified delay time, or does the response vary under different conditions?

  2. SHUTDOWN MODE Exit Timing: According to the datasheet, the BQ40Z50 exits SHUTDOWN MODE when a charge is applied, with the requirement being >3V. However, the datasheet does not specify how long the voltage needs to be applied for the device to exit SHUTDOWN MODE. Is there a defined time duration for this condition, or any available test data that provides insights into this?

I would greatly appreciate your guidance or any additional documentation that might provide further clarification on these points.

Thank you for your time and support.

  • 0
    TI__Mastermind 28480 points

    Hi Tom,

    Tom Tsao said:
    Command Reception Timing: When sending commands to the BQ40Z50 through the EV2400, how long does it take for the device to receive and process the command? Is there a specified delay time, or does the response vary under different conditions?

    The communication between the EV2400 and bq40z50 is typically ran at 100kHz, regarding how long the processing takes for the device I believe this can be different from command to command. Typically if the gauge needs to indicate to the host that it is still busy it can implement clock stretching, which has a max timing of 25ms.

    Tom Tsao said:
    SHUTDOWN MODE Exit Timing: According to the datasheet, the BQ40Z50 exits SHUTDOWN MODE when a charge is applied, with the requirement being >3V. However, the datasheet does not specify how long the voltage needs to be applied for the device to exit SHUTDOWN MODE. Is there a defined time duration for this condition, or any available test data that provides insights into this?

    I believe the voltage on the pack pin needs to be apparent for at least two sample periods of 500ms length. The image below is for the emergency FET shutdown, but I believe the sampling on the pack pin in shutdown should work on the same timing factor: