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BQ24296M: BQ24296M Failed with SYS pin and Bat PIN short to GND problem

Jimmy Huang22
Expert 1470 points
Part Number: BQ24296M
Other Parts Discussed in Thread: BQ24296

Hi Ti team,

    I find some  BQ24296M failed, the SYS pin to GND short 100R ,BAT pin to GND short also. Other pins no find failed. Vbus=5V , BAT=4.2V

The QON Pin pull up a 5.1K resistor from 4.4V (PMU Output voltage).

Could you pls help us confirm whether it is ok  QON from a 4.4V voltager from a 5.1K resistor?

  • Are there other possibilities for causing this damage SYS and BAT pin short to GND?

thanks!

  • 0
    TI__Mastermind 25800 points
    Hey Jimmy,

    Is this a custom board or on our EVM?

    If custom, do you have a schematic you can provide?
    Can you also describe your testing conditions before the damage and immediately following?
    And also please provide the register settings you programmed into the charger.
    Do you have any scope captures of the input voltage, output voltage, battery voltage, etc?

    The absolute maximum rating on QON is 7V, as per the datasheet specification. Does your PMU have any over-voltage events on startup or during operation or with a load transient?


    Regards,
    Joel H
  • 0 in reply to Joel Hernandez II
    Expert 1470 points

    Joel,

        Thanks for your reply

    1,In Customer board,Since other projects have been mass produced, this problem has not been found before.Now 381 project trial production found a bit high rate of defects.There is one difference between these two projects in this part of the circuit, and the others are the same: the previous mass production projects are labeled R401 and R391 NC.381 project trial production R401 NC, R391 5.1k resistor

    2,SCH as below,

    • were found no problem in the test of semi-finished products, and damages were found in the assembly of finished products.

        • Good products Normal aging did not occur for 24 hours

    3, we test SW pin no short to GND

    • Can Vin voltage problems cause this phenomenon Bat and sys pin short to GND?

      • What voltages do you think are likely to cause this damage?

    • I ask customer to test Bat pin,Qon pin and SW voltage.

  • 0 in reply to Jimmy Huang22
    TI__Mastermind 25800 points
    Hey Jimmy,

    This is only a partial schematic. Can you provide more detail than this showing the entire charger circuit components and pins?

    One major point is also the maximum voltage on VSYS or VBAT cannot execeed 6V as per the datasheet Absolute Maximum rating. If the battery is detachable or has a high impedance/inductance from it to the charger's BAT pin, a heavy load or inrush current may cause overshoots.


    Regards,
    Joel H
  • 0 in reply to Joel Hernandez II
    Prodigy 10 points

    Hi JOEL,

    This is the entire charger circuit components and pins.

    Now,we find when the DC source plugs in,the Vsys become 0.6V suddently.

    We change a new bq24296,Phenomenon disappeared .And Charging is normal.

  • 0 in reply to weiyue liang
    TI__Guru 57481 points

    Hi,

    The schematic is hard to read.

    Thanks,

    Ning.

  • 0 in reply to Ning T
    TI__Guru 57481 points

    Hi,

    We haven’t heard back from you for a while, the thread is considered solved and closed.

    Thanks,

    Ning.