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BQ24012: BQ24012. Battery Charger Termination Issues (SLVA166A)

Alberto Lubeiro
Prodigy 170 points
Part Number: BQ24012
Other Parts Discussed in Thread: BQ24010

I have a BQ24012 into a new design. A battery charger.

The fact is that this battery charger works fine when it is alone, i mean the battery charger and the battery. The red led is ON and once the battery is charged the green led is the one that is ON.

But when i connect another boad to the battery charger while the battery is charging something is happening cause when i disconnect the USB cable so the battery stop charging , the red Led remeins ON.

I have found the Application report SLVA166A but in the first pharagraph i don't see the BQ24012 part number, so my question is: is this part number being affected by this issue?, does this part number belong to this document?

I have been talking via live chat to a person who has said to me that she thinks this errata doc does not apply anymore but in anyway it has a strange behavior.

Any advice to fix this issue is welcome.

Thanks and best regards.

  • 0
    TI__Intellectual 1980 points

    Hello

    For the reason that we don't know which pins do the red/green LED are connected, could you please upload the SCH, that will help to analyze, thanks.

    Regards.

  • 0 in reply to Kerry Song
    Prodigy 170 points

    Hello,

    Sure, please find attached the SCH.

    The red Led is DS1

    I have seen various behaviors:

    1- The charger connected to the USB, the battery not connected to the charger and a load (control board or a simple resistor) connected to the charger

    The RED  led"DS1" turns ON

    2- The charger connected to the USB, the battery connected to the charger and a load (control board or a simple resistor) connected to the charger

    In this situation, The RED led is on cause the battery is charging but when i remove the USB cable from the PC:

    - In case the resistor is connected the RED led turns off.

    - In case the control board is connected. the RED led remains on.

    Hope i have explained clearly enough

  • 0 in reply to Alberto Lubeiro
    Prodigy 170 points

    Don't know why it didn't attached the SCH.

    I attach it again.

    Thanks and best regards!

  • 0 in reply to Alberto Lubeiro
    TI__Intellectual 1980 points
    Hello

    what's the value of the resistor which you connected to charger's BAT pin？ Recommend that you test the waveform of IOUT, VIN, VOUT, START, that will help to analyze what was happened, thanks

    Regards
  • 0 in reply to Kerry Song
    Prodigy 170 points

    Hello,

    I'll check them out, but in the meantime can you please tell me if this errata document i mentioned before afects to our reference BQ24012??

    As for the value of the resistor, it a 18ohm one but i have also tried with a 12Kohm just in case it is due to low current loads.

    Thanks and best regards

  • 0 in reply to Alberto Lubeiro
    TI__Intellectual 1980 points
    Hello

    Yeah, BQ24012 belongs to the application report document, BQ24010 and BQ24012 is a family.
  • 0 in reply to Kerry Song
    Prodigy 170 points

    Hello,

    A couple of things:

    1- The errata document's last revision is from October 2006 and the BQ24012 datasheet is from January 2014. In Texas live chat someone told me that she thought this errata document was no applied anymore cause the datasheet was later than the errata document. Are you sure this errata document is still applicable??

    2- May this issue be the reason of the weird behavior of the charger when the control board is connected? By the way, i have realised this weird behavior happens when the battery is quite chargered.

    Thanks and best regards.

  • 0 in reply to Alberto Lubeiro
    TI__Intellectual 1980 points

    Hello

    As for datasheet, 2014 just means there are updated contents in 2014, because datasheet sometimes need add or modify, this part is not designed by 2014.

    As for SLVA166A termination issue, the document tells us which situation will cause the issue, 1."If the load current is greater than the taper threshold, then the taper timer is not set, and normal termination does not occur". 2."Applying a system load, while the charger is in pre-charge conditioning mode, reduces or eliminates the pre-charge current potentially keeping the cell below 3 V,causing the charger to enter fault mode."

    so recommend that you could test/detect the load current, and then you could determine it exactly.

    Regards