TIDUFB6 December   2024

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1System Description
  8. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Considerations
      1. 2.2.1 Multiplexer Network and Switch Strategy
      2. 2.2.2 Cell Balancing
      3. 2.2.3 Stacked AFE Communication
      4. 2.2.4 MCU and CAN Interface
    3. 2.3 Highlighted Products
      1. 2.3.1 BQ78706
      2. 2.3.2 TMUX1308
      3. 2.3.3 TCAN1044-Q1
      4. 2.3.4 MSPM0G3519
      5. 2.3.5 LMR51406
      6. 2.3.6 ISO7731
      7. 2.3.7 UCC33420
      8. 2.3.8 UCC33421
      9. 2.3.9 TMP61
  9. 3Hardware, Testing Requirements, and Test Results
    1. 3.1 Hardware Requirements
    2. 3.2 Test Setup
    3. 3.3 Test Results
      1. 3.3.1 Daisy Chain
      2. 3.3.2 Cell Voltage Accuracy
      3. 3.3.3 Temperature Sensing Using TMP61
      4. 3.3.4 Temperature Sensing Timings
      5. 3.3.5 Cell Balancing and Thermal Performance
      6. 3.3.6 Current Consumption
  10. 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
  11. 5About the Author

3.3.2 Cell Voltage Accuracy

This design does not perform any calibrations to further improve the cell voltage accuracy since the BQ78706 already achieves ±2.4mV accuracy at –40°C to 125°C. The typical voltage range of a LiFePO4 cell is from 2.5V (0% SOC) to 3.6V (100% SOC), so the design uses a battery simulator to provide cell voltages from 2.5V to 3.6V to verify the VCELL accuracy of the BMU.

The maximum error of all cell channels for the BQ78706#1 is 0.7mV at a room temperature of 22.7°C. Figure 3-2 shows the cell voltage accuracy.

TIDA-010279 Cell Voltage Accuracy Figure 3-2 Cell Voltage Accuracy