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BQ34110: VEN pin behavior

Mark Scovel
Intellectual 595 points
Part Number: BQ34110

We enabled the VEN pin (using pin control config by programming our data flash at startup) because we use an external voltage divider.

But we find that the VEN pin is turning on for 125 ms and then off approx. every 18 seconds even when our code is not running or talking to the bq device.

Why is this?

It seems like the TRM should discuss this fact.

It would be good to know what the impact is to the bq device behavior if the VEN pin is off when we've turned it on.

  • 0
    TI__Mastermind 25955 points

    Hi Mark,

    Is your device set to enter sleep mode? Is any action being performed that would otherwise prohibit the device from entering sleep?

    If not, please refer to the Sleep Voltage Time parameter. The default for this value is 20 s. 



    With respect to your approx 18s concern:

    As described in Section 2.10.3 SLEEP Mode of the TRM:

    During SLEEP mode, the gas gauge periodically takes data measurements and updates its data set.
    However, a majority of its time is spent in an idle condition. The interval at which the device wakes to take
    measurements is set by the data flash values of Sleep Current Time and Sleep Voltage Time.


    With respect to the VEN pin turning on for 125 ms:

    As for VEN_EN, you have stated that you have enabled the pin. Please refer to Section 2.2.1 Pin Control Config for a description of

    VEN_EN: VEN pin control for external voltage divider operation
    When set, the VEN pin is used to control an external voltage divider, which provides the divided
    down voltage to the BAT pin. Setting this pin also disables the use of the internal battery voltage
    divider within the device. When this bit is cleared, the internal battery divider will be activated
    whenever a battery voltage measurement is activated.

    Sincerely,
    Bryan Kahler

  • 0 in reply to Bryan Kahler
    Intellectual 595 points
    Sleep was on so I turned it off and find that the device is still cycling the VEN pin (now at 5 seconds).
    Does the device turn off the pin when it goes to sleep?
    We have nothing connected to the VEN pin so it probably doesn't matter but it was discovered while trying to make sure the code to turn it on was being tested. If the VEN pin is off (after we turned it on) is the internal voltage divider selected or does the fact that we turned it on to select external voltage divider keep the external voltage divider selected even when the VEN pin is turned off by sleep?
  • 0 in reply to Mark Scovel
    TI__Mastermind 25955 points
    Hi Mark,

    The VEN pin will still cycle in sleep mode, but at a much slower rate than when in Normal mode.

    Sincerely,
    Bryan Kahler