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BQ27421-G1: 95uA Iq in Hibernation

Aaron Jones
Intellectual 760 points
Part Number: BQ27421-G1

Hi Team,

I'm seeing a fuel gauge consume 95uA in hibernation--I'm not sure if it really is getting into hibernation.

As specified by the bq27421-g1a, supply current to the chip in hibernate mode is ~9uA . But even after conditions for the gauge entering in to hibernate mode are met, we see supply current of ~92uA to battery gauge.  All communications to the chip are pulled down.

I am using a switch to power off the system except the battery gauge and real time clock(RTC). Both battery gauge and RTC share the I2C bus, which is pulled down due to system power off.

--> On battery gauge shutdown mode and on system power off, I see system supply current to be 2.6uA(~0.6uA for battery gauge and ~2.0uA for RTC).

--> On configuring battery gauge to enter hibernation mode and on system power off, I see system supply current to be 95uA as specified by the reference manual

 I configured the Hibernate V = 5000 mV • FH Setting 0 = 0 • FH Setting 1 = 1 • FH Setting 2 = 0 • FH Setting 3 = 0 and has set            CONTROL_STATUS[HIBERNATE] = 1, for the battery gauge to enter in to the fast hibernation mode.

  What should I do to get hibernate mode current specified by the datasheet?

  • 0
    TI__Guru 61986 points
    Hello,

    Please try to leave SCL/SDA high and check if the gauge enters hibernate mode.

    Regards,
    Dominik
  • 0 in reply to Dominik Hartl11
    TI__Intellectual 760 points
    Hi Dominik,

    Thanks for this tip. We performed some additional tests, no dice:

    1) configured battery gauge to enter into fast hibernate mode and put the master SOC to sleep mode(GPIOs are active, means SCL / SDA are high). I see supply current fluctuating from 366uA to 460uA.
    2) configured battery gauge to enter shutdown mode and put the master SOC to sleep mode(GPIOs are active, means SCL / SDA are high). I see supply current stayed constant at ~345uA.

    from test one it looks like battery gauge is fluctuating between normal mode and hibernate mode even when there is no bus activity.

    Any advice?