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Original question:

BQ27510. CC Gain, CC Delta. Computation.

BQ34Z100-G1: CC Gain, CC Delta.

user5766630
Prodigy 60 points
Part Number: BQ34Z100-G1
Other Parts Discussed in Thread: BQSTUDIO

Hi,TI

The current is 1000mA but Current(): 0x10/0x11 report the current is 1400mA.

I have read How EVSW Display the Raw Data V1.03.pdf,and can change CC Gain between 0x7F71205C and 0.47095 correcly.

My question is :How can I use  CC Gain and CC Delta WITHOUT using Evalution Software to Calibrate the current?. Any relationship between CC Gain and CC Delta?

Best Regards

Haokai Sun

  • 0
    TI__Mastermind 25955 points
    Hi Haokai Sun,

    As shown in Table 11 of the datasheet, as stored on the device:

    CC Gain is of Class Calibration, subclass Data, with a subclass ID 104, offset of 0 and type Float 4 bytes with a range from 1.00E-01 to 4.00E+01.
    CC Delta is of Class Calibration, subclass Data, with a subclass ID 104, offset of 4 and type Float 4 bytes with a range from 2.98E+04 to 1.19E+06.

    As shown in Table 12 of the datasheet, as converted by EVSW:

    CC Gain has a data flash default of 0.47095 and a EVSW default of 10.124 so a conversion factor of 4.768 / Dataflash value must be used to see what is displayed in EVSW when reading from the device.

    CC Delta has a data flash default of 5.595E5 and a EVSW default of 10.147 so a conversion factor of 5677445 / Dataflash value must be used to see what is displayed in EVSW when reading from the device.


    To calibrate the current without using EVSW:

    CAL_ENABLE 0x002D (Control subcommand)
    ENTER_CAL 0x0080 (Control subcommand)
    >> Follow the Steps in section 7.3.3.1 For accessing the dataflash and use the information above for CC Gain and CC Delta
    EXIT_CAL 0x0082 (Control subcommand)


    The relationship between CC Gain and CC Delta:

    CC Gain is the gain factor for calibrating Sense Resistor, Trace, and internal Coulomb Counter (integrating ADC delta sigma) errors. It is used in the algorithm that reports Average Current.

    CC Delta is the gain factor for calibrating Sense Resistor, Trace, and internal Coulomb Counter (integrating ADC delta sigma) errors. It is used in the algorithm that reports charge and discharge in and out of the battery through the Remaining Capacity register.

    The difference between CC Gain and CC Delta is that the algorithm that reports Average Current cancels out the time base because Average Current does not have a time component (it reports in mA) and CC Delta requires a time base for reporting Remaining Capacity (it reports in mAh).

    Sincerely,
    Bryan Kahler
  • 0 in reply to Bryan Kahler
    Prodigy 60 points
    Dear Bryan Kahler

    Thank you very much.

    ----------------------------------------------------------
    To calibrate the current without using EVSW:
    CAL_ENABLE 0x002D (Control subcommand)
    ENTER_CAL 0x0080 (Control subcommand)
    >> Follow the Steps in section 7.3.3.1 For accessing the dataflash and use the information above for CC Gain and CC Delta
    EXIT_CAL 0x0082 (Control subcommand)
    -----------------------------------------------------------
    After ENTER_CAL, I should write the CC Gain and CC Delta value to the dataflash , but how to get the CC Gain and CC Delta value?
    Should I force a known load current like 1000 mA?

    Best Regards,
    Haokai Sun
  • 0 in reply to user5766630
    TI__Mastermind 25955 points
    Hi Haokai Sun,

    1. To get close initially, the CC Gain and CC Delta values should be set to that of the measured resistance of your current sense resistor.
    2. Force a known current such at 1000 mA.
    3. Obtain the CC offset and Board offset from DF
    4. Obtain avgRawCurrent
    5. ccGain = current / (avgRawCurrent - (ccOffset + boardOffset) / 16 )
    6. ccDelta = ccGain * 1193046
    7. Convert ccGain and ccDelta to Gauge's floating point representation and write to DF

    This process is much easier if bqStudio is used and the value is saved into the golden image to be used in production.

    Sincerely,
    Bryan Kahler
  • 0 in reply to Bryan Kahler
    Prodigy 60 points
    Dear Bryan Kahler,
    Thank you!This helped a lot.

    Best Regards,
    Haokai Sun