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BQ25892: BQ25892+BQ28Z610

Redwood
Expert 1060 points
Part Number: BQ25892
Other Parts Discussed in Thread: BQ28Z610, BQSTUDIO

Hi, 

I am trying to change the battery charge voltage setting by using " Battery management studio" software. 

1- I changed "charge voltage limit" as shown below. I saw the effect at the BAT output of BQ25892 EVM as shown in the figure below. 

2- BAT output of BQ25892 is driving the (Pack +/- ) of BQ28z610

3- when I monitor the BATTERY VOLTAGE at the GAUGE ( 28z610 ) , I don;t see the battery voltage is changing. WHY?

Thanks and best regards,

  • 0
    TI__Guru**** 166176 points

    Redwood,

    First, when using BQStudio to control the charger, I recommend switching to Field View button two buttons over from the Tgt Address.  It is easier to read.

    Then, disable the Watchdog timer.   I also suggest confirming that the input current setting is high enough for your desired charge current.  Please note the resistor on the ILIM pin clamps input current regardless of input current limit register setting. There is a register bit to disable the ILIM pint.  

    Also, you can Enable ADC and perform a Read All, you use the charger's ADC to confirm input voltage, input current, battery voltage, as seen by the charger etc.  The input voltage at the charger's VBUS pin needs to be higher than the VINDPM setting or the charger will reduce input current to zero to prevent.

    If the input current limit is being reduced for some reason (IINDPM, VINDPM, etc.) the charger current may be too low to see a fast change in battery voltage.  A LiIon battery sits at 3.6-3.8V for a long time while charging at a 1C rate.

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Expert 1060 points

    Hi, 

    I still have the same question & the results is still the same. The system consists of Charger(bq25892) and Gauge(bq28z610). 

    I don't see the change in battery voltage even though the setting in the charger is changed. ( "Charge Voltage Limit" is changed to 3.840V BUT "BATTERY VOLTAGE" is still 4.05V "   WHY? "

    I changed the view. Disable the "watchdog". Disable "ILIM pin". Changed "Charged Voltage Limit".  I also added the load 

    thanks and best regards,

  • 0 in reply to Redwood
    TI__Guru**** 166176 points

    Hi Redwood,

    BQStudio is reporting Charge Terminated.  If the actual battery voltage is above the charger's regulation voltage, the charger will not actively discharge the battery and cannot start charging until the battery discharges VRCH volts below the regulation voltage.

    Regards,
    Jeff

  • 0 in reply to Jeff F
    Expert 1060 points

    Hi, 

    The input voltage to GAUGE is higher than Battery Voltage which is also connected to Gauge. 

    Can you provide me a initial setting for bq28z610 with a given battery voltage that I can see charging?

  • 0 in reply to Redwood
    TI__Guru**** 166176 points

    Redwood,

    I am renaming and moving this post to the gauge forum.

    Regards,

    Jeff

  • 0 in reply to Redwood
    TI__Guru* 76230 points

    Hi Redwood,

    The default values on the gauge should allow you see charging once you turn on the charge fets. Send the fet enable command using bqstudio to turn on the fets.

    thanks

    Onyx