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BQ27520 -Cycle count and battery detection

Likhitha Eugene James P
Expert 2270 points

Hi,

In TRM page no.14 it is mentioned that 

"The gauge maintains a separate cycle counter for both cell profiles and resets to 0 if the insertion of a new
pack has been detected."

1.The same battery used if  removed and reconnected will the cycle count be reset to 0?

When adapter is not connected ,with the half charged battery (less than 3v) is battery detection possible using BI/TOUT Pin.

Thanks.

  • 0
    TI__Guru* 76230 points

    1. When the cell is inserted, the devices carries out an OCV measurement and resistance measurements and then tries to  compare the measured resistance to the cell profiles. There are 2 profiles that could get updated and there is the default profile corresponding to a new battery. Now if it decides it is a new battery, the default profile will be copied to one of the profiles and that profile cycle count will be reset to zero.

    2. The device uses the thermistor of the battery to decide if a battery is inserted. When there is no battery, that pin is pulled high, but when the battery is inserted, the thermistor pulls that pin low. As long as the device is powered on, either by the cell or external source, it will be able to detect a battery is inserted.  The threshold for the device to be powered on is about 2.5V

    thanks
    Onyx

  • 0 in reply to Onyx Ahiakwo
    Expert 2270 points
    Hi Onyx,

    Thanks for the reply.
    In our system we plan to configure fuel gauge in battery always present condition.So host need to inform fuel gauge about the battery removal and insertion.Also the fuel gauge gets power from the battery,so if remove it loses power.In this context can you help to clarify the below points.
    "When the cell is inserted, the devices carries out an OCV measurement and resistance measurements and then tries to compare the measured resistance to the cell profiles"
    1.Whether the fuel gauge will automatically perform this process during every POR ?
    2. Does the host need to inform the gauge about cell insertion?
    3.Within how much time does the gauge perform this process and decide new cell or not?

    "As long as the device is powered on, either by the cell or external source, it will be able to detect a battery is inserted."
    I am little confused with the statement.If the gauge is powered from the cell then how can we detect a battery insertion?Does this mean during every POR gauge will check for profile matching to identify whether new cell or not?

    Thanks,
    Likhitha
  • 0 in reply to Likhitha Eugene James P
    TI__Guru* 76230 points
    hi Likithita,
    1.Whether the fuel gauge will automatically perform this process during every POR ?
    OA:Yes, As long as there is a POR on the gauge IC, it will perform the check. The guage is never supposed to undergo a POR, but if that happens the it performs the process.
    2. Does the host need to inform the gauge about cell insertion?

    OA: If your cell is embedded and is non-detachable you do not need to have your host always send the BIE command. You can use your thermistor so the gauge uses that to detect the battery is alway inserted, or if the BIE flag in data flash is cleared, then the host has to always sent the battery insert command whenever there is a POR.
    3.Within how much time does the gauge perform this process and decide new cell or not?
    OA: less than 1s.


    "As long as the device is powered on, either by the cell or external source, it will be able to detect a battery is inserted."
    I am little confused with the statement.If the gauge is powered from the cell then how can we detect a battery insertion?Does this mean during every POR gauge will check for profile matching to identify whether new cell or not?
    OA: Yes, ever POR the gauge willl do the profile matching.

    thanks
    Onyx