SLUAA32A October   2020  – September 2021 BQ769142 , BQ76922 , BQ76942 , BQ76952

 

  1.   Trademarks
  2. 1Production Programming of BQ769x2 Device Family
  3. 2Calibration
    1. 2.1 Calibration Accuracy
    2. 2.2 Cell Voltage Gain Calibration
      1. 2.2.1 Cell Voltage Gain Calibration Steps
    3. 2.3 Cell Voltage Offset Calibration
      1. 2.3.1 Cell Voltage Offset Calibration Steps
    4. 2.4 TOS (Top-of-Stack), PACK, and LD Pin Voltage Calibration
      1. 2.4.1 TOS / PACK / LD Voltage Calibration Steps
    5. 2.5 ADC Gain Calibration
    6. 2.6 Current Calibration
      1. 2.6.1 Board Offset Calibration Steps
      2. 2.6.2 CC Gain Calibration Steps
    7. 2.7 Temperature Calibration
      1. 2.7.1 Temperature Calibration Steps
    8. 2.8 COV and CUV Calibration
      1. 2.8.1 COV Calibration Steps
      2. 2.8.2 CUV Calibration Steps
    9. 2.9 Calibration Code Example
      1. 2.9.1 Code Example
      2. 2.9.2 Code Output
  4. 3OTP Programming
    1. 3.1 Recommended Steps for Writing OTP in Production
  5. 4References
  6. 5Revision History

2.6.2 CC Gain Calibration Steps

  1. Disable Sleep Mode (Subcommand 0x009A) to ensure voltage counts update quickly after applying a voltage.
  2. Apply a known current ICAL (typically 1 A to 2 A) and ensure current is flowing through the sense resistor connected between the SRP and SRN pins.
  3. After 100ms, read CC2 Counts using the READ_CAL1 subcommand 0xF081. For best accuracy, take multiple readings and calculate the average.
  4. Calculate the CC Gain:
    Equation 4.
    GUID-D3F7C214-8D1B-4EBC-9C0D-2A647DEE1EFB-low.gif
  5. Calculate the value for Capacity Gain. Capacity Gain is simply the CC Gain multiplied by 298261.6178.
  6. Write the new CC Gain value to RAM. CC Gain must be encoded using the 32-bit IEEE-754 floating point format. A code example is provided later in this document that includes computing this format.
    • Enter CONFIG_UPDATE mode (Subcommand 0x0090).
    • Write CC Gain to 0x91A8.
    • Write Capacity Gain to 0x91AC.
    • Exit CONFIG_UPDATE mode (Subcommand 0x0092).
  7. Re-check the Current() reading. If the reading is not accurate, repeat steps 1-5.
Table 2-4 Current Calibration Parameters
Parameter Name Physical Start Address Type Min Max Default Units
CC Gain 0x91A8 F4 1.00E-01 10.00E+00 7.4768 -
Capacity Gain 0x91AC I2 2.98262E+04 4.193046E+06 2230042.463 -
Coulomb Counter Offset Samples 0x91C6 U2 0 65535 64 -
Board Offset 0x91C8 I2 -32767 32767 0 -