TIDUF44 January   2024

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1System Description
    1. 1.1 Key System Specifications
  8. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Highlighted Products
      1. 2.2.1 BQ76907
      2. 2.2.2 BQ76905
      3. 2.2.3 BQ77207
      4. 2.2.4 MSPM0L1106
      5. 2.2.5 TCAN1042
      6. 2.2.6 TPSM365R6V5
      7. 2.2.7 TLV704
      8. 2.2.8 TMP61
  9. 3System Design Theory
    1. 3.1 Primary Protection Design
    2. 3.2 Secondary Protection
    3. 3.3 Other Circuit Design
  10. 4Hardware, Software, Testing Requirements, and Test Results
    1. 4.1 Hardware Requirements
    2. 4.2 Software Requirements
    3. 4.3 Test Setup
    4. 4.4 Test Results
      1. 4.4.1 Cell Voltage Accuracy
      2. 4.4.2 Pack Current Accuracy
      3. 4.4.3 Protection
      4. 4.4.4 Cell Balancing
      5. 4.4.5 Working Modes Transition
      6. 4.4.6 Thermal Performance
  11. 5Design and Documentation Support
    1. 5.1 Design Files
      1. 5.1.1 Schematics
      2. 5.1.2 BOM
    2. 5.2 Tools and Software
    3. 5.3 Documentation Support
    4. 5.4 Support Resources
    5. 5.5 Trademarks
  12. 6About the Author

4.4.2 Pack Current Accuracy

This design uses two parallel 2-mΩ, 2-W, 50-PPM shunt resisters to measure pack current. Board offset was calibrated using the guidance of the calibration section of the data sheet. Next, Current Gain was calibrated with 2-A discharging current. Write the Board Offset and Current Gain values with OTP to BQ7690X; otherwise, the MCU has to store such data and write to BQ7690X every time the MCU wakes up from shutdown mode.

Figure 4-4 shows the pack current accuracy data under room temperature. The maximum current error is about ±10 mA when the discharging current is below 3 A and about ±0.5% when the discharging current is above 3 A.

GUID-20231010-SS0I-0SCJ-W1W4-VXNZV2BXK2G9-low.svg Figure 4-4 Pack Current Accuracy