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BQ24103A chip failures

mike holz
Prodigy 80 points
Other Parts Discussed in Thread: BQ24103A

I'm experiencing an occasional BQ24103A chip failure during power cycling tests.

Brief circuit summary: Power to my board is provided by an external 230VAC-to-24VDC COTS power supply. When 24VDC is present, power is delivered to my main circuit through D14. Power to the charger chip is from a simple switcher stepping down the 24VDC to 12VDC (U32). When 24VDC is present the battery charger chip is powered and continuously charges the battery until full. When 24VDC is removed due to a power outage or other means, my main circuits remain powered via the 7.4VDC Li-Ion battery pack (with protection circuitry) through diode D15. Note that power switchover components Q11, R95, R94 and Q12 are not installed and I elected to use just the diode since this is not a portable power device and I can afford the increased losses of the diode. During these power outage conditions the BQ24103A is off due to the input voltage not being there.

During testing we are cycling AC power which causes the main 24VDC supply to turn off, thereby turning off the DC/DC supply forcing the board to be powered by the battery. I now have two or three instances where this testing has caused a catastrophic failure of the BQ24103A chip. I have scoped all power lines and signals looking for voltage spikes which may causing a temporary overvoltage condition but have not observed anything that looks suspicious. Thus far I have not identified a root cause of the failure.

Questions: Is anyone else seeing sporadic failures of this chip? Is there anything inherently wrong with my design topology which would cause the BQ24103A to fail?

5543.0300241_A0- Power Sheet.pdf

  • 0
    Prodigy 100 points

    I am replying because I am having BQ24103A failures on a 10 bay battery fixture. I use 10 copies of the circuit and a main 110-220 to 15V DC power Supply capable of 300W. I already use this circuit in my handheld meter to charge my 2S1P LiOn pack with no trouble so far. However, as we entered larger scale production, I built 8 of these 10 bay battery chargers so we can pre-charge 80 batteries every 2 hours. I have only had them running a week and I am getting about 1 or 2 individual BQ24103A circuits having catastrophic failure on the IC. This has me seriously worried about my handheld product in the field.

    I too have scoped all lines and have not seen any power spikes or other bad signals on any of the lines. I am including my sch / pcb pictures as well.

  • 0 in reply to Gary Sinde
    Prodigy 100 points

    To clarify: I am having 1 or 2 circuits a day failing. I have lost a total of 9 circuits in the last week. Thanks

  • 0 in reply to Gary Sinde
    Prodigy 60 points

    Hi Gary,

       Have you resolved your issue? I, too, have had some similar concerns.

  • 0 in reply to CHARLES Custon
    Prodigy 100 points

    I made a work around that appears to be holding. I basically had to prevent my production floor folks from plugging in batteries to a powered up charging circuit. I had to put a timer on my charging station and a lid. When the batteries are done, main power is cut off, and they can lift the lid, replace the 20 batteries, and reload the next set of 20 batteries. It doesn't make sense and I think there is a problem with the chip or the reference design but I didn't have time to keep working on it. I am seeing no field failures of my portable devices using the same charging circuit but those batteries are never removed / replaced while power is applied.

  • 0 in reply to Gary Sinde
    TI__Mastermind 31120 points

    there are no know problems with this IC and millions have been sold...probably means your field devices are good.

    The charger is sensitive to reverse connections and negative connections....anything that would cause the substrate not to be the lowest bias.

    Typically power sources are keyed so reverse connections are impossible.

    If a battery is plugged in backwards, that is the obvious failure.  Other things to consider is multiple chargers in parallel and many packs being inserted and unplugged at the same time.  If the three contacts of each cell are disconnected in different orders, while the charge is active, there could be some negative voltage.

    Example: the thermistor is referenced to the ground so if the ground connection is broken leaving the BAT+ and thermistor connection and the charge terminates causing the BAT+ to jump down in voltage the negative end of the battery jumps down the same amount and could go below ground.  Since the TS is reference to this floating node, the TS pin goes negative.  Most battery packs are designed so the TS connection is in the middle making this scenario impossible.

    Anyway, I would put two schottkys from ground (Annode) to BAT+ and TS (cathode).  Maybe this will help.