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BQ76952: SLEEP-Mode and BOTHOFF functionality

Klaus
Expert 1210 points
Part Number: BQ76952
Other Parts Discussed in Thread: BQSTUDIO,

Hi Ti Experts,

we want to use the bq76952 in standalone mode for a 16S6P (21,6Ah) LiFePo application.

So far we have designed and produced a first PCB version.

We are using the BOTHOFF functionality to switch off the FETs if the battery is not mounted in the system.

That is working so for.

Also I want that the bq enters the SLEEP-Mode. For that I have activated the SLEEP-Bit:

If the battery is mounted in the system and the BOTHOFF-Pin (Pin30) ist conntected to Battery-Minus the bq enters the SLEEP-Mode:

If the battery is not in the system (BOTHOFF-Pin is connetect to 3V3) the bq stays in NORMAL-Mode:

Is there any opportunity to enter SLEEP-MODE if the battery is not mounted in the system (BOTHOFF-Pin is connetect to 3V3)?

Thanks for helping us.

Klaus

  • 0
    TI__Guru* 78003 points

    Hi Klaus,

    I just tested your settings on my EVM and I am able to see the device go to sleep in both states (BOTHOFF connected to 0V and BOTHOFF connected to 3.3V). Is there anything else enabled in the system that might be preventing Sleep mode? Could the device be seeing some current across the sense resistor? 

    There are some other parameters under the Power:Sleep settings that may be worth looking into that affect when Sleep is entered.

    Best regards,

    Matt

  • 0 in reply to Matt Sunna
    Expert 1210 points

    Hi Matt,

    thanks for your answer.

    Here are the parameters under Power:Sleep I am using:

    I have also tested these one, but nothing have changed:

    I do not think that the device is seeing some current, because the FETs are off.

    What things can prevent Sleep-Mode?

    Am I able to send you the whole gg-file in a private message?

    Thanks for helping us.

    Klaus

  • 0 in reply to Klaus
    TI__Guru* 78003 points

    Hi Klaus,

    I sent you a private message and you can respond with your gg file. Another thing that wakes up the device is communications. If you turn off the Dashboard in BQStudio and turn off the Scan feature on the main screen, this will stop the GUI from communicating with the device in the background. 

    Matt

  • 0 in reply to Matt Sunna
    Expert 1210 points

    Hi Matt,

    thanks for your answer.

    I have sent you the gg-file in private message.

    I have diconnected the communication completly. Also I have conected the communication-lines to GND, but the
    bq76952 stays in NORMAL-Mode.

    Thaks for helping us.

    Klaus

  • 0 in reply to Klaus
    TI__Guru* 78003 points

    Hi Klaus,

    Thanks for sharing your gg file. I seem to have been able to narrow down this behavior to the PDSG_EN bit in the FET Options register. If I turn this bit off, the device will enter SLEEP mode. I am investigating this and will let you know what I learn.

    Best regards,

    Matt

  • 0 in reply to Matt Sunna
    Expert 1210 points

    Hi Matt,

    thanks for your answer.

    I  am able to reproduce, what are you writing.

    If I turn off the PDSG_EN bit in the FET Options register, the device will enter SLEEP mode.

    I think our customer needs the predischarge feature.

    Thanks for helping us.

    Klaus

  • 0 in reply to Klaus
    TI__Guru* 78003 points

    Hi Klaus,

    I will close this thread temporarily since we have an ongoing discussion through private messages. I will update this thread once we reach a conclusion.

    Best regards,

    Matt