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waking BQ20Z65 up from shutdown

Timothy Starr
Expert 2445 points
Other Parts Discussed in Thread: BQ20Z65

Hello-

We have copied our battery pack design from sheet 19 of the BQ20Z65 data sheet. The data sheet says that at least 1uA is needed into the PACK pin to wake the device up from shutdown. We wish to use the lowest possible current/voltage to do this, for safety reasons.

What is the maximum current this crcuit will take into the PACK+ connector, at a Vstartup of 5.5V, in order to be assured the device will wake up? Note that the PACK+ terminal connects to ressitors, FETs, and other pins of the BQ20Z65, complicating the analysis. Thanks in advance for your help, and Best Regards,

-Tim Starr on behalf of MF@HW

  • 0
    TI__Guru* 76230 points

    Hi Tim,

    The data sheet says the max current (Ipack) and not the min current is 1 uA.

    thanks

    Onyx

  • 0 in reply to Onyx Ahiakwo
    Expert 2445 points

    Hi Onyx-

    Yes I read and understood the data sheet. The maximum current that the IC needs corresponds to the minimum current which we must be able to supply it. So please don't get hung up on that word.

    Also, I am asking about the curretn into the reference circuit in the data sheet, not simply the IC itself. Do you understand the question?

    -Tim

  • 0 in reply to Timothy Starr
    TI__Guru* 76230 points

    Tim,

    I am still befuddled by your question. The condition for exit from shut down mode is that the pack voltage has to be greater than its minimum operating voltage. The IC Pack pin is only connected to pack + through the 1k inrush current limiting resistor. R24 in the data sheet is not populated. When the charger is connected to the connector, if the gas guage is not in precharge mode, and when not tapering, the charge current is the minimum current through the pack + connector.

    thanks

    Onyx