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

2.7.1 Temperature Calibration Steps

The below steps are the same for each of the enabled temperature measurements. In this example, the steps are shown for the Internal Temp Offset and TS1 Temp Offset only.

  1. Apply a known temperature, TEMPCAL, to the device and to thermistors connected to external thermistor pins.
  2. Read the temperatures using the temperature measurement commands. For example, read Internal temperature (TINT_measured) with command 0x68, TS1 temperature (TS1_measured) with command 0x70. The values returned by the temperature commands are in 0.1K units, so these should be converted to Celsius.
  3. For best accuracy, take multiple readings and calculate the average.
  4. If temperature offsets have been previously written, write the offsets back to their default values the Temperature Calibration Settings. These values are set to zero by default.
  5. Calculate the temperature offset for each of the measurements. In the equations below, the temperature units are in 0.1K. So for example, 2981 would represent 25C.
    • Internal Temp Offset = TEMPCAL - TINT_measured
    • TS1 Temp Offset = TEMPCAL - TS1_measured
  6. Write the new Internal Temp Offset and TS1 Temp Offset values to RAM.
    • Enter CONFIG_UPDATE mode (Subcommand 0x0090).
    • Write Internal Temp Offset to 0x91CA.
    • Write TS1 Temp Offset to 0x91CE.
    • Exit CONFIG UPDATE mode (Subcommand 0x0092).
  7. Re-check the temperature readings using the temperature measurement commands. If the reading is not accurate, repeat steps 1-6.