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BQ24232HA: Question about fault timer and \CHG status indicator

Chase Jeong
Mastermind 7485 points
Part Number: BQ24232HA

Tool/software:

Dear TI experts,

My customer tests BQ24232HA in their own PCB.

They tested fault timer as the steps below ;

1. Set precharge timer to  44 min.

2. start charging

3. Checks that \CHG LED is blinking at 2Hz after 44 min, because the battery voltage could not reach V_lowv.

4. After few time passed, \CHG LED is continuously on, not blinking.

- Is No. 4 normal operation?

- Or Am I missing something?

- Anyway I want to know that \CHG LED is blinking at 2Hz continuously after fault timer expires. and there is no reset.

Please check this issue. Thanks.

Best regards,

Chase

  • 0
    TI__Mastermind 31420 points

    Hi Chase, 

    On BQ24232HA expectation is /CHG status LED will blink at 2Hz when safety timer expires and battery charge is suspended until a new cycle is initiated.

    This part has been released to market for some time and does not have a known issue regarding the safety timer wrongly resetting on its own. I have also double checked in lab and 45 minutes after safety timer initially expired /CHG LED was still blinking at 2Hz. I do not observe any reset issue. 

    Chase Jeong said:
    4. After few time passed, \CHG LED is continuously on, not blinking.

    Can you please check if customer is performing any action between 3. and 4.? For example, toggling /CE pin or unplugging then replugging input adapter would reset the charge safety timer.  

    Best Regards,

    Garrett 

  • 0 in reply to Garrett Kreger
    Prodigy 60 points

    Dear Garrett,

    I connected a 56kΩ resistor to the TMR pin to set the precharge timer to 44 minutes.
    Can you please check if customer is performing any action between 3. and 4.?
    --> I was just observing and didn’t perform any actions.

    From what you're saying, I understand that it should continue operating with flashing at 2Hz.
    If there's a way to maintain continuous operation with flashing at 2Hz, please let me know.

    I want to get your email address so I can send my schematic.

    thanks,

    Seungyoon

     

  • 0 in reply to Seungyoon Baek
    Prodigy 60 points

    Dear Garrett,

    I got the plot for blinking LED.

    please refer to the measurement waveform.

    Yellow (CH1) is bat1,2 and Blue (CH2) is CHG/ pin.

    What I want should keep blinking, but it's not happening.

    Thanks,

    Seungyooon

  • 0 in reply to Seungyoon Baek
    TI__Mastermind 31420 points

    Hi Seugyoon, 

    Please see my comments below. 

    Seungyoon Baek said:
    I want to get your email address so I can send my schematic.

    I have sent you a friend request via E2E. Once you accept I can share my email address via private message, alternatively if you wish you can simply share your schematic file via private message feature on E2E. 

    Thank you for providing a waveform of the behavior. Based on my review I believe I have determined why /CHG LED stops blinking in your system.

    It appears to be due to the drop in VBAT when charge is suspended due to timer expiration. I have verified in our lab that battery voltage dropping below Vbat(sc) threshold (battery short circuit threshold, typ 1.8V max 2V listed on datasheet page 7) results in a reset. When VBAT reduces /CHG LED turns off and device is no longer in 'safety timer expired' state. 

    If you repeat your test but ensure battery voltage remains in precharge range (>2V and <3V) I expect device to stay in continuous operation with charge suspended and /CHG LED flashing at 2Hz.

    Best Regards,

    Garrett 

  • 0 in reply to Garrett Kreger
    Prodigy 60 points

    Dear Garrett,

    I understood your comment.  I ask for my schematic review and sent a direct message.

    Please take a look at my schematic. 

    Thanks,

    Seungyoon.

  • 0 in reply to Seungyoon Baek
    TI__Mastermind 31420 points

    Hi Seungyoon, 

    I have reviewed your schematic and all looks okay. All required components are present and you have the correct resistor values to set the charge parameters you specified. 

    Best Regards,

    Garrett 

  • 0 in reply to Garrett Kreger
    Prodigy 60 points

    Dear Garrett

    Thank you for your comments.

    Thanks,

    Seungyoon