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BQ78350-R1: How is the precharge of bq78350-r1 prohibited?

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Replies: 11

Views: 256

Part Number: BQ78350-R1

Hi,

The BQ78350-R1 is in precharge Mode, the Precharge FET is ON but the CHG FET left-over ON. I have attached picture, Why the AFE doesn't oppenned  the CHG FET ?

  • Hi Loic,

    This behavior depends on the settings of the FET_Options settings in Data Memory. Check specifically the setting of the PCHG_EN bit.

    Best regards,
    Matt

     

  • In reply to Matt Sunna:

    Hi Matt,

    I had the PCH_EN enabled

    Best regards,

    Loïc

  • In reply to LOIC REBOUSSIN:

    Hi Loic,

    In Section 5.2 of the TRM for this device, there is a table showing that this bit should be set to zero for the PCHG FET to be used instead of the CHG FET:

    Can you try to set this to zero to see if it resolves the issue?

    Thanks,

    Matt

     

  • In reply to Matt Sunna:

    Hi Matt, This solution doesn't resolve my issue because this table are false, your colleague has confirmed that before

    Follow this link :

  • In reply to LOIC REBOUSSIN:

    Hi Matt,
    Can you still help me ?

    Best Regards,
    Loïc
  • In reply to LOIC REBOUSSIN:

    Hi Loic,

    Sorry for the delay - I needed to investigate a little more. You are correct that the TRM table does need to be updated. I will get this updated in the next revision of the document.

    However, after looking more at your image of the Register screen, I am not sure why you say the CHG FET is enabled. I circled the CHG bit below which is green indicating the CHG FET is off. The xCHG bit indicates that charging is enabled which is correct since the device is pre-charging. It does not refer to the FET state.

    Best regards,

    Matt

     

  • In reply to Matt Sunna:

    Hi Matt,

    The precharge doesn't works because the CHG FET is closed (XCHG flag of operation Status is green, it does refer to the FET state.) so there are no limitation of current.
    Best regards.
    Loïc
  • In reply to LOIC REBOUSSIN:

    Loic,

    The 'PCHG', 'DSG', and 'CHG' bits indicate the status of the FETs. Your register screen is showing the PCHG FET is active and the CHG and DSG FETs are inactive. I agree the 'XCHG' bit does not refer to the FET state. It just indicates that charging is not disabled.

    Are you saying the CHG FET is closed on the hardware even though it is showing as disabled in the Register? Can you send a log of the charging process (To save a log file, click on the 'Start Log' button on the Registers window) and also the data flash settings (To save the dataflash settings, click on the Export button on the Data Memory window)? It might also be good if you can send the schematic.

    Best regards,
    Matt

     

  • In reply to Matt Sunna:

    Hi Loic,

    Do you have any update on this issue?

    Thanks and best regards,
    Matt

     

  • In reply to Matt Sunna:

    Hi Matt,

    I will tried to record a precharge scenario today,

    I'll let you know

    Best regards,

    Loïc

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