TIDUF14 October   2022

 

  1.   Description
  2.   Resources
  3.   Features
  4.   Applications
  5.   5
  6. 1System Description
  7. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Considerations
    3. 2.3 Highlighted Products
      1. 2.3.1 BQ76952
      2. 2.3.2 LM5163
      3. 2.3.3 MSP430FR2155
      4. 2.3.4 ISO1042
      5. 2.3.5 TPS54308
      6. 2.3.6 ISO7731
      7. 2.3.7 THVD1400
      8. 2.3.8 UCC27524
      9. 2.3.9 TMP61
  8. 3Hardware, Software, Testing Requirements, and Test Results
    1. 3.1 Hardware Requirements
    2. 3.2 Test Setup
    3. 3.3 Test Results
      1. 3.3.1 Cell Voltage Accuracy
      2. 3.3.2 Pack Current Accuracy
      3. 3.3.3 Auxiliary Power and System Current Consumption
      4. 3.3.4 Cell Balancing
      5. 3.3.5 Protection
      6. 3.3.6 Working Modes Transition
  9. 4Design and Documentation Support
    1. 4.1 Design Files
      1. 4.1.1 Schematics
      2. 4.1.2 BOM
    2. 4.2 Tools and Software
    3. 4.3 Documentation Support
    4. 4.4 Support Resources
    5. 4.5 Trademarks
  10. 5About the Author

3.3.2 Pack Current Accuracy

This design uses four 2-mΩ, 2-W, 50-PPM shunt resisters in parallel to measure pack current. Board offset was calibrated using the guidance of the Calibration section of the BQ76952 Evaluation Module user's guide. Then current gain was calibrated with 5-A discharging current and also followed the guidance of the Calibration section of the BQ76952 Evaluation Module. Write the board offset and current gain values with OTP to the BQ76952, otherwise the MCU has to store such data and write to the BQ76952 every time the MCU wakes up from shutdown mode. Figure 3-3 shows the pack current accuracy data under room temperature. The maximum current error is below ±30 mA when discharging current is below 5 A and ±0.5% when discharging current is above 5 A.

Figure 3-3 Pack Current Accuracy