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BQ25723: SYSOVP appears at high temperatures

Star Xu
Genius 9645 points
Part Number: BQ25723

Hi 

The customer design with BQ25723, BQ25723 is designed with 4 series cells, and CELL_BATPRESZ is set to 75% VDDA. The VSYS output voltage is 12.3V when the battery is not inserted at room temperature, and it can work normally for a long time. Put the device in this state into a 70℃ high temperature thermostat. After working for about 10 minutes, the charge controller turns off and the SYSOVP changes to 1.

Use an oscilloscope to measure the voltage waveform of VSYS and find that VSYS continues to increase from 12.3V in the high temperature thermostat, and finally the controller shuts down after reaching about 19.5V.

 BQZ Container: Charger_1_00-BQ25723.bqz
*
Charge Option 0 070E
Charge Current 0000
Max Charge Voltage 41A0
Input Voltage 3200
Min System Voltage 6C00
IIN_HOST 7F00
IIN_DPM FF00
Charge Option 1 EF10
Charge Option 2 32BF
Charge Option 3 0434
Prochot Option 0 4AFD
Prochot Option 1 81FF
Charge Option 4 E048

Please help check it.

Thanks

Star

  • 0
    TI__Expert 3335 points

    Hi Star,

    Since the battery is not inserted, can you pull CELL_BATPRESZ to ground and test at 70℃ and see if  VSYS still hits SYSOVP?

    Best Regards,

    Munir

  • 0 in reply to Md Munir Hasan
    TI__Genius 9645 points

    Hi Munir

    Thanks for your reply.

    The customer will try this state. But is this initial voltage 1S? They need to change the register setting to 4S?

    Thanks

    Star

  • 0 in reply to Star Xu
    TI__Expert 3335 points

    Hi Star,

    What initial voltage of 1S are you referring to?

    As long as there is no battery CELL_BATPRESZ should be 0V. When there is battery you can change to 1S or 4S according to your need.

    Please obtain scope captures of VBAT, VSYS, SW1, SW2 nodes also when testing at 70℃.

    Best Regards,

    Munir

  • 0 in reply to Md Munir Hasan
    TI__Genius 9645 points

    Hi Munir

    Thanks for your help.

    The customer do the test as below:

    Set CELL_BATPRESZ to 0V and VSYS is 4.2V at room temperature. Setting the 0B/0C register can modify VSYS to 12.3V.

    Set CELL_BATPRESZ to 0V at 70℃, if the 0B/0C register is not set, VSYS will also output higher than 12.3V, and the voltage of VSYS will gradually increase. When they measured it, it has reached 20.5V. Does it normal?

    Thanks

    Star

  • 0 in reply to Star Xu
    TI__Expert 3335 points

    Hi Star,

    The part does not have 0B/0C register. I believe you mean 0D/0C VSYS_MIN() register. 

    With CELL_BATPRESZ =0V and without setting 0D/0C register, VSYS should be 3.6V at room temp. Not 4.2V.

    With CELL_BATPRESZ =0V, the SYSOVP is 25V.

    1. Are you seeing SYSOVP triggered at 70℃ when VSYS gradually increases to 20.5V?

    2. Do you have any load attached to VSYS?

    3. Please obtain register map and scope captures of VBAT, VSYS, SW1, SW2 nodes from the customer at 70℃. 

    As far as I know increasing temperature should not increase VSYS. Please confirm if the following information for your case is correct or not.

    Settings

    Result

    CELL_BATPRESZ =0V

    VSYS = 12.3V and gradually increases to 20.5 V

    SYSOVP hits = yes/no?

    0D/0C not set (at default)

    Temp = 70℃

     Is this correct?

    Best Regards,

    Munir