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TIDA-00792: Some questions about TIDA-00792.

Tom Tsao
Intellectual 290 points
Part Number: TIDA-00792
Other Parts Discussed in Thread: BQ76930, BQ78350

Tool/software:

Hi E2E,

My customer wants to replace the BQ78940 with the BQ78930 in the reference design for a 7-s application.

Please help clarify the questions below.

  1. Please provide the ESD protection circuit for the BQ76930. After developing this IC, there is an issue of voltage imbalance between the upper and lower five cells after 50 cycles. What could be the possible cause of this?  
  2. When both the BQ76930 and BQ78350 are in Sleep mode, can the C & D_FETs remain in the ON state? Also, when the AFE and GAUGE enter Sleep mode, can the power consumption be less than 500 µA?
  3. Can the DISP pin be configured to show the corresponding SOC on the LED when set as a push button? If so, can I use this button to wake up the GAUGE and AFE?

           

        4. When both the BQ76930 and BQ78350 are in Sleep mode, what behaviors can wake up the BQ78350? Can the detection of current by Rsen wake it up?

        5. Can the LED 1~5 display states be customized?

Thanks!

  • 0
    TI__Guru 54276 points

    #1: Are you asking about the internal ESD protection on the chip?

    #2: You can control if the gauge turns off the charge fet with FET Options. See TRM, 8.3.1, first table, "Actions". Sleep current typ < 500uA average. Note that this isn't a constant current but may spike up periodically.

    #3: See TRM, 13.2.1 about display activation. One mode is /DISP = low for <LED Hold Time, which looks like what you want. The gauge and AFE automatically wake up when necessary (if in sleep). If in shutdown, you need to apply the wake up voltage on the AFE as described in 8.4

    #4: The gauge wakes up periodically (sleep measure time) and with the conditions from TRM, 8.3.1, Status "Exit".

    #5: All configuration options are listed in the TRM, 13.4  

  • 0 in reply to Dominik Hartl11
    Intellectual 290 points

    Hi Dominik,

    For question1, 

    I need your help to suggest an external ESD protection circuit for BQ76930.

    For question3,

    One mode is /DISP = low for <LED Hold Time, which looks like what you want. The gauge and AFE automatically wake up when necessary (if in sleep). 

    =>Where can I find this description in the TRM or elsewhere?

    Thanks a lot!

  • 0 in reply to Tom Tsao
    TI__Guru 54276 points

    #1: What pins are exposed to potential ESD events in this application?

    #3: The information is in the TRM, 13.2.1: It explains that you have to pull /DISP low for LED Hold Time and additional requirements, depending on selected options (like LEDR or LEDCHG). Further information is in the whole chapter 13.2 on all the available options. 8.3 explains the requirements for entering and exiting sleep mode.