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BQ27742EVM: BQ27742-G1

kavya medandi
Prodigy 170 points
Part Number: BQ27742EVM

Hi,

Currently I'm working on BQ27742 EVM Shutdown mode. I'm able to go into analog shutdown mode and come out of it. But where I'm facing issue is, after coming out of Analog shutdown, I'm immediately reading PMIC readings. But it is taking 500ms to give ACK from PMIC. Can I know how much time it will take for PMIC to respond after coming out of Analog shutdown mode. And what is the time taking for PMIC to activate, when battery is connected to cell+, cell-.  I need to get at least 10ms after wake up of PMIC from Analog shutdown mode.

Thanks in advance,

Kavya. 

  • 0
    TI__Guru 57697 points

    Hello Kavya,

    Recovering from Analog Shutdown is similar to rebooting the gauge. It takes approx 600ms for initialization. To get good readings we recommend waiting 4 seconds because of the various filters that will prevent sudden changes to register values.

  • 0 in reply to Shirish
    Prodigy 170 points

    Hi Shirish,

    If it takes 600ms approx. Our application needs less than this time. So can I go with full sleep mode. But my requirements are current<100uA when entered into full sleep mode and read with in less time like 10ms. But when I'm measuring current of only EVM board I'm getting 600-700uA  when entered into full sleep mode. Is it because of EVM components. Because datasheet mentioned like full sleep has nominal current of 40uA. 

    How to enter into full sleep?

    Thanks in advance,

    Kavya.

  • 0 in reply to kavya medandi
    TI__Guru 57697 points

    Hello Kavya,

    Shutdown mode is intended for storage/shipping. FullSleep is meant for a system that is in use, so yes, you should use FullSleep.

    For the command for full sleep See TRM section 4.1.1.12 SET_FULLSLEEP: 0x0010

    The conditions are also listed. FullSleep mode will be entered only after current goes below Sleep current.

    The EVM current consumption seems high even for normal mode. I would suggest that you disconnect the load and communication lines when measuring EVM current consumption. You may also want to check other parts of your system that may consume power.