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BQ25895: BQ25895 ESD issue

Rock Shao
Expert 2995 points
Part Number: BQ25895

Hi Team,

During the ESD test, I found that the LED was flickering. After reading the register, I found that there was an abnormality in the Flag test. From which Flag can I find the problem? Thank you.

U3=U4=BQ25895

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  • 0
    TI__Mastermind 32020 points

    Hello, 

    -When you say the LED was flickering are you referring to the LED connected to STAT pin?

    -I am not sure what you mean by flag test can you further clarify?

    -Can you please help to share all operating conditions during this test such as VBUS, VBAT, VSYS, etc.? 

    Best Regards,

    Garrett 

  • 0 in reply to Garrett Kreger
    Expert 2995 points

    Hi Garrett,

    In addition, the customer found the adapter AC ON/OFF test with QUAIL V2(NUVOTON MCU) and battery.
    Turn on→Turn off(about 700mS to 800mS)→ Turn on again
    Such a test will also find the same situation as the surge test.

    Please help to check the register, if there has any fag can find the problem? Thank you.

    Stopped charging.

  • 0 in reply to Rock Shao
    TI__Mastermind 32020 points

    Hi Rock, 

    I have reviewed the registers attached and they do not show any fault conditions on the charger. Please help to answer my questions from my previous response as well as explain the problem the customer is seeing in more detail. Based on your current description I cannot tell what issue the customer is facing. 

    Best Regards,

    Garrett 

  • 0 in reply to Garrett Kreger
    Expert 2995 points

    Hi Garrett,

    Excuse me, I reorganize the current situation as the following.

    By the test. ST and NUVOTON MCU is still alive and the two I2C bus worked well when the ESD discharging issue appeared. Please check whether the BQ25895RTWR register recovers to the default value when 12V deep drops. And please advise what situation that second LED will light up by FW. Thanks.

    -When you say the LED was flickering are you referring to the LED connected to the STAT pin?

    Ans: The STAT pin is floating. and the LED connected to MCU

    -Can you please help to share all operating conditions during this test such as VBUS, VBAT, VSYS, etc.? 

    Ans: See the attached~

    CWT-Quail V2 IC waveform.xlsx

  • 0 in reply to Rock Shao
    TI__Mastermind 32020 points

    Hi Rock, 

    You mention the LED is connected to the MCU. Since it is not an LED connected to a BQ25895 pin I am not able to comment on this LEDs expected behavior. 

    When 12V supply at VBUS is removed if a valid battery remains connected to BAT pin registers should not reset to default. Registers are expected to reset to default when there power lost at both VBUS and BAT pins. 

    In the provided waveform capture what is the blue signal measuring? I do not know what TP8 / TP14 is referring to. 

    Best Regards,

    Garrett 

  • 0 in reply to Garrett Kreger
    Expert 2995 points

    Hi Garrett,

    My customer used two BQ25895 in this system, the TP8/TP14 is the Vbat.

    And I can send the schematic to you.

  • 0 in reply to Rock Shao
    TI__Guru 57831 points

    Hi Rock,

    We will get back to you by next Wednesday.

    Thanks a lot,

    Ning.

  • 0 in reply to Ning T
    TI__Mastermind 32020 points

    Hi Rock, 

    I have answered your question regarding if register reset. Is there any other issue the customer is seeing? 

    I have a couple comments regarding the schematic you shared. Please see below. 

    -Customer is not using the correctly sized inductor for their design. The BQ25895 is designed to be used with a 1 uH or 2.2 uH inductor.

    -Capacitance at PMID pin should not be more than 60 uF. 

    Otherwise the customer schematic looks okay. 

    Best Regards,

    Garrett