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Original question:

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

BQ40Z50: exit shutdown mode delays

Makabongwe Ncube
Prodigy 80 points
Part Number: BQ40Z50
Other Parts Discussed in Thread: BQSTUDIO

Tool/software:

Hi Engineers, 

I am using the BQ40Z50-R1 on one of my battery packs, I am successfully managed to get the FG into  shutdown mode . The issue comes when getting the pack to exit shutdown mode. 

I am connecting the pack to a charger that's is continuously pulsing high for 900ms and low for 100ms, the pulse voltage applied is 16V. This  is for a 4s1p Li-ion charger. 

I am noticing a delay of about 20s for my battery pack to exit shutdown mode and register voltage on the P+, I cant seem to understand where the delay is comes from as my understanding is that  exiting the shutdown mode is hardware based, and its through applying a voltage pulse !? 

I am writing  to verify if at all there is  some sort of a "delay value" that could be programmed perhaps, to delay the BQ40Z50-R1 from waking up from shutdown by a defined amount? This would help identify if there are any specific parameter settings affecting the shutdown exit timing that I may be missing.

  • 0
    TI__Mastermind 26475 points

    Hello Makabongwe,

    A delay of 20s is very unusual and wanted to reach out to see if this is happening with multiple system or if it could be a damage IC. There is no parameters within Data flash memory that you can use to lower the exiting of shutdown mode. When you exit out of shutdown mode you should look at the "INIT" register to see when shutdown mode is existed. Worst case scenario I would need to review your schematic to verified your hardware is in check

    Thank you,
    Alan


  • 0 in reply to Alan Frias
    Prodigy 80 points

    Hi Alan, 

    Many thanks for your response.  Indeed the INIT flag is turned ON. In my application, we interface the Fuel Gauge IC with an MCU via the SMBus. What I noticed is that when I hold the MCU in reset while the BQ is being pulsed by the charger. The Fuel Gauge does exit the Shutdown mode as expected (quick). 

    Question.

    Is there any other condition thats required  so the IC to exit shutdown mode - other than applying a pulse to the P+ to get the fuel gauge out of shutdown mode ?  e.g. no comms on the SMBus,? or the fuel gauge should not see any current drawn when waking up? 

  • 0 in reply to Makabongwe Ncube
    TI__Mastermind 26475 points

    Hello Makabongwe,

    The conditions to exit and enter into shutdown mode is listed below and founded in section 5.4.1 Voltage Based Shutdown in the technical reference manual. The other way to exit and enter shutdown is through ManufacturerAccess commands also listed below, but this is only meant for the developer and not the end user. I would recommend and see if you can recreate the long wake up time within other units to see if it's just this one unit. But if that turns to be recreatable in multiple units a review of your hardware and BQstudio would be needed.

    Thank you,
    Alan

  • 0 in reply to Alan Frias
    Prodigy 80 points

    I suspect that it's something to do with my gg.cvs files but cant quite point to it yet. Tests are ongoing.

    Please find attached my gas gauge files—one that works fine and another that experiences a wake-from-shutdown delay.

    My main question is regarding how the Data Memory > Gas Gauging section functions, specifically how these values are updated -  is it an automatic process based on IT algorithm - over time? or these values need to be set from the onset.

    My application uses a 4S1P configuration. You'll notice that the difference between these two files is an additional cell Qmax value being added.

    It appears that the key to resolving the issue lies in this difference between these two files.

    I appreciate your insights!



    works_fine.gg.csvdelayed_wake_from_shutdown.gg.csv 

  • 0 in reply to Makabongwe Ncube
    TI__Mastermind 26475 points

    Hello Makabongwe,

    We have received your question and we are working to a solution.

    Thank you,
    Alan