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Original question:

BQ40Z50-R2: Will not charge unless there is SMBus communication with the part.

BQ40Z50-R2: Is the SMBus really required for the battery assembly and charger to function correctly?

Josel Go
Expert 6010 points
Part Number: BQ40Z50-R2
Other Parts Discussed in Thread: BQ40Z50

Hi Experts,

Good day.

Our customer is asking if the SMBus really required for the battery assembly and charger to function correctly?

Section 8.3.3 Charge Control Features of the attached owner manual states the following:

"Reports the appropriate charging current needed for constant current charging and the appropriate charging voltage needed for constant voltage charging to a smart charger using SMBus broadcasts"

Is this to say that in order for the battery assembly and charger to function correctly together, the BQ40Z50RSMT needs to be able to communicate with the external charger IC via the SMBUS connections? Or can the batteries be charged correctly without the SMBUS connections between the BQ40Z50RSMT IC and the charger IC? In other words, can they function independently without any data communication between the battery assembly and the charger while the charging is taking place?

I only ask because my application is for an intrinsically safe (IS) product and these data connections would need to be protected from a mains power failure (250V) in order to comply with the regulations and subsequently require additional intrinsic safety-related components. Therefore, if these data connections are not required, I will not establish external connections for the SMBD and SMBC data lines. However, if they are required, I will do so and integrate the required IS components into the design.

Keep safe.

Regards,
Josel

  • +1
    TI__Expert 8315 points

    Hi Josel,

    The BQ40Z50 can function independently of the charger without a connection via SMB to the charger IC itself. Charge control features will just not be possible without this connection. All charging related parameters will need to be controlled by the charger IC itself without direct control from the BQ40Z50.

    Best Regards,

    Jackson

  • 0 in reply to Jackson DiGiovanna
    TI__Expert 6010 points

    Hi Jackson,

    Thank you for your response.

    The customer has a follow-up query.

    When you say charge control features, do you mean the over-charge protection feature for example? And therefore if the SMBUS connections are not in place, the charger IC will need to be capable of monitoring the individual cell voltage levels in order to trigger a FET to shut off the flow of current?

    Keep safe.


    Regards,

    Josel

  • 0 in reply to Josel Go
    TI__Expert 8315 points

    Hi Josel,

    This is correct. Basically by charge control features, I am specifically referring to the ability for the gauge to control the behavior of a Charging IC directly. Without the SMB connections to the charger, the gauge will have to trigger a FET to shut off the flow of current if a protection were to trigger as you mentioned.

    Best Regards,

    Jackson

  • 0 in reply to Jackson DiGiovanna
    Intellectual 320 points

    Hi Josel and Jackson

    Saw this thread and figured I would ask some questions directly here. I am the customer! I appreciate the feedback provided above as it's very helpful. One follow up question I have is whether the BQ40Z50RSMT is also capable of implementing the charging profile (pre-charge / constant  current / constant voltage) without the SMBD and SMBC interconnections between the BQ40Z50 IC and the charger IC.

    Best regards,

    Joe DeWItt

  • 0 in reply to Joseph DeWitt
    TI__Expert 8315 points

    Hi Joseph,

    Would you mind making this question its own thread? We prefer to have each question be its own post so that others can find these specific responses easier in the future, rather that your question be buried underneath many replies on a separate post.

    If you wouldn't mind making this question its own post, I will reply to you directly there.

    Thanks!

    Jackson