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BQ34110: BQ34110, vbat reading 0 V

Michael Desjardins
Intellectual 580 points
Part Number: BQ34110
Other Parts Discussed in Thread: BQSTUDIO

Hi,

I'm using the BQ34110 with an external voltage divider (two 100k resistor). The max battery voltage of the system is 4.5V.

The control of the BQ34110 is done with a microcontroller via I2C interface. I'm trying to read the battery voltage but still reading 0V.

I've send the I2C command to put the bq34110 in CAL mode (Calibration mode) and set the VEN_EN bit at 1. 

Here is a picture of the VEN output that enable my voltage divider to the bat input of the bq34110.

Here is a picture at the BAT input:

I should be reading 2.2 V and I read 0 V. I don't understand why.

Thank you!

Michael

  • 0
    TI__Guru* 76230 points
    are you able to access other registers properly in the gauge and able to communicate with bqstudio properly? if your stack voltage is 4.5V, then that means you individual cell voltage would be 2.25 and that appears too low to power on the LDO that powers the device.

    thanks
    Onyx
  • 0 in reply to Onyx Ahiakwo
    Intellectual 580 points

    Hi Onyx,

    I'm able to read the current register, the temperature register with adequate values.

    I'm also able to read registers in the flash memory.

    The device is powered with a 3.0 V LDO that is power by the Stack.

    The 2.25 V is after the voltage divider, the input of the voltage divider is the stack voltage and the output is at the BAT input.

  • 0 in reply to Michael Desjardins
    Intellectual 580 points
    Hi,

    I've found my problem, I'm posting it here for others who might have the same problem.

    I'm using an external voltage divider, the voltage at the BAT pin can't exceed 1V when using an external voltage divider. I've changed the bottom resistor of the my divider to a value in order to have a voltage value lower than 1V when I have the maximum battery stack voltage.

    Michael