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BQ24163: Will not charge unless I remove and reinsert battery

Mark S.
Prodigy 130 points
Part Number: BQ24163

We use the BQ24163 chip in one of our products and are having an issue with the charging process. The units will work fine, charge and discharge several times, then all of a sudden they will not charge anymore from USB or from wireless. They will turn on and discharge just fine but will not charge. they only way we've found to solve this is to unplug the Li-Ion battery and then plug it back in, after that it will charge just fine. It seems the charger IC is stuck in a certain state and the act of removing the battery and inserting it again forces a reset. This is a rare occurrence but is still an issue, we of course need a solution that doesn't involve removing the battery. What could cause this to happen?

  • 0
    TI__Guru*** 148825 points

    Hi Mark,

    Battery remove/replace forces a new charge cycle.  I need a bit more information.  What do the charger's I2C status and fault registers report when this happens?  Does it only happen at a certain battery voltage?  Do you have access to the CD pin?  If so, if you toggle the CD pin, does this also reset the charger?

  • 0 in reply to Jeff F
    Prodigy 130 points

    Thanks for the quick reply.

    What do the charger's I2C status and fault registers report when this happens?

    -Unfortunately I cannot connect the debugger to the unit and pull the chargers register values because as soon as I hook up the cable, the voltage spike on the line somehow causes the charger to reset and it will then charge the battery. Once this happens, the problem is no longer present and not easy to duplicate.

    Does it only happen at a certain battery voltage?

    -It is hard to say what voltage level this happens at. The problem happens in the field and the users continue to use the unit for some time before sending it in. The 2 units I have in the lab right now are at ~3.9v and ~3.8v.

    Do you have access to the CD pin?  If so, if you toggle the CD pin, does this also reset the charger?

    -I do have access to the CD pin. I used a jumper wire to toggle it and the charger reset and is charging now. 

  • 0 in reply to Mark S.
    TI__Guru*** 148825 points

    Mark,

    If toggling CD (chip disable/HiZ) mode restarts charge, the I2C registers and TS pin appear to be okay but the state machine is forcing HiZ for some reason.    I am not aware of an issue with this charger's state machine. 

    Can you send your schematic?  To what voltage source are the charger's SDA and SCL pullup up? 

    As a fix, can you modify the software to toggle the CD bit after input power is applied and after safety timer expires?  Toggling CE (charge enable) bit might work as well and, unlike CD, does not turn on the buck converter.

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Prodigy 130 points

    Jeff, see the schematic below:

    The I2C lines are pulled up to 3v3 as noted in the schematic above. On startup our code sets the CE bit low and pulls the CD pin low. Also, we already toggle the CD pin after the 9 hour safety timer has expired. 

  • 0 in reply to Mark S.
    TI__Guru*** 148825 points

    Mark,

    I do not see any errors on the schematic.

    Toggling /CE restarts the charge cycle.  Toggling CD pin or HZ_MODE bit resets the state machine.  Without knowing the fault that caused the charging to stop charging, the best I can recommended is writing the code to toggle HZ_MODE bit or CD pin whenever charging stops.  If charge is complete, the charger should immediately terminate.  If you toggle /CE or HZ_MODE bits or CD pin, the safety timer is reset.

    Regards,

    Jeff