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BQ76942: Discharge/Charge FETs not turning on

Mark Philip Felipe
Genius 9705 points
Part Number: BQ76942

Hi Team, seeking some advice.

PCB which utilizes the BQ76942PFBR for the monitoring and protection of 8 LiPo cells. I successfully gotten the BQ76942PFBR to communicate with a PIC microcontroller via SPI, where I am able to observe the cell voltages etc. I am not currently able to get the discharge/charge FETs to turn on. I am measuring a voltage of 11v across the charge pump capacitor. Is there a list of things/registers that I should be checking in order to determine why the FETs aren't turning on? Could I have potentially missed a command that needs asserting?

Thank you.

/cfs-file/__key/communityserver-discussions-components-files/196/Battery-Board-V4.pdf

Thank you.

-Mark

  • 0
    TI__Intellectual 2865 points

    Hi Mark, 

    Can you please confirm the FET_ENABLE command has been sent (0x0022) or that the FET_EN bit has been set in the Mfg Init Config register?


    If this has already been done you can verify the state of the CHG and DSG FET in the FET Status register to see if this matches what you are measuring on the CHG and DSG pins.

    You can also double check that the FET_CTRL_EN bit is set in the FET Options register to allow host control of the FETs, though this is enabled by default but it would be good to verify. 

    Best, 

    -Luis T