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

4.4.3 Protection

The design integrates a full set of battery cell protections, including: cell overvoltage, cell undervoltage, two levels of overcurrent discharge, overcurrent charge, discharge short circuit, overtemperature and undertemperature protections. Furthermore, this design also monitors loss of system level faults, including: cell open wire, host watch dog, charge and discharge MOSFETs faults, overtemperature, and so on. Some of the protections were tested in a TI lab.

GUID-20230906-SS0I-3BF9-NB9B-HCN6TDSQJLPK-low.png
CH1 (Blue): Battery voltage, CH2 (Cyan): DSG V_gs, CH4 (Green): Discharge Current
Figure 4-5 Overcurrent Discharge (Set the Threshold to 10 A)
GUID-20230906-SS0I-C4BK-SLJH-HV4DZSWKQLPL-low.png
CH1 (Blue): Battery voltage, CH2 (Cyan): DSG V_gs, CH4 (Green): Discharge Current
Figure 4-6 Overcurrent Charge (Set the Threshold to 10 A)
GUID-20230906-SS0I-JT5G-RV9J-JD5L9VSCQWHP-low.png
CH1 (Blue): DSG V_ds, CH2 (Cyan): DSG V_gs, CH4 (Green): Discharge Current
Figure 4-7 Discharge Short Circuit (Set the Threshold to 20 A)
GUID-20230906-SS0I-3X4S-HW4H-VC4V9TGZW9KL-low.png
CH1 (Blue): DSG V_ds, CH2 (Cyan): DSG V_gs, CH4 (Green): Discharge Current
Figure 4-8 Discharge Short Circuit (Set the Threshold to 30 A)

This design also includes the individual secondary protections to prevent the hazards from each cell overvoltage and overtemperature. This helps to pass some safety regulations without further work. Secondary overvoltage protections were tested in a TI lab.

GUID-20230906-SS0I-LL3L-Q5QJ-WZXMVPLLXJBK-low.png
CH1 (Blue):Cell 1 voltage, CH2 (Cyan): VCOUT
Figure 4-9 Secondary Overvoltage Protection