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BQ25898D: Troubleshooting help

Yuxi Liu(Tony)
Expert 4420 points

Part Number: BQ25898D

Hi TIer

My customer have find a fault chip of BQ25898D in mass production.

The chip pin impedance did not change significantly. and BQ25898D could not communicate and also no output (0V at SW, SYS, PMID). We suspect internal damage to the chip, so we have externally supplied 4.0V to the REGN pin in anticipation of activating the chip. When I power the REGN pin externally, I notice that SW and PMID and SYS are showing battery voltage, which proves that the internal MOS is working properly. However, still no communication in I2C and can't charge battery when I connect USB Vbus 5V. The control circuit of the drive section may fails.

Is there any more testing options to help me locate the problem? I want to find out the cause of the damage. Please give me some advice, thank you 

  • 0
    TI__Mastermind 18975 points

    Hi,

    One thing I would recommend is an A-B-A swap, to confirm that the behavior follows the IC and is not specific to the board that you are observing the behavior on. Confirming proper soldering on the IC would also be important.

    I would also measure leakage current at VIN and VBAT, to compare with the specifications. Deviating from this seems to indicate failure. Biasing REGN is expected to cause SW, SYS and PMID to rise since there is a diode and body-diode path between all these nodes.

    With damage it is very difficult to know exactly what the cause of the failure is since it can be control circuitry or physical damage to the IC. If this failure is observed multiple times or there is concern that it might happen again, I would recommend reaching out to a Field Quality Engineer on how to proceed.

    Best Regards,

    Juan Ospina

  • 0 in reply to Juan Ospina
    TI__Expert 4420 points

    We conducted impedance tests for both the VIN and VBAT, and the result was that there was no short circuit and the impedance at the MΩ level. Also, since the chip is used in handheld devices, in order to prevent customers dropping device. The glue was make on the surface of the BQ25898D, it cannot be removed for ABA testing, removal will cause chips to break.

    Do we have more detailed testing can prove that the chip is good, but not functional? Field quality engineers need BU to agree that it is a quality issue before they can begin a quality analysis.

  • 0 in reply to Yuxi Liu(Tony)
    TI__Mastermind 18975 points

    Hi Tony,

    If this is damage related than it is very difficult to say exactly how the device will fail, so there isn't really a detailed test procedure other than to run the device through ATE. Typically an A-B-A swap will be used to confirm that the rest of the surrounding circuit on the board is working and the issue is specific to the IC. If that is confirmed then the device is put through the return process to see if it fails in ATE testing and to run failure analysis to find the cause of the failing behavior. In order to pass it through ATE testing to confirm if the chip is damaged, the device has to be removed from the board regardless.

    Applying 5V as measured at the VIN pin and measuring 0V on PMID shows unexpected behavior. Applying 4V at VBAT and measuring 0V on SYS, (after /QON press to confirm ship mode exit if necessary) also shows unexpected behavior. Identifying the actual cause of the behavior is something we can't do easily outside of the return process.

    Best Regards,

    Juan Ospina