TIDUEB2A July   2022  – July 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
      1. 2.2.1  Power Multiplexing Circuit Design Parameters
      2. 2.2.2  Input Connections and Filter
      3. 2.2.3  Reverse Polarity Protection
      4. 2.2.4  Battery Charger Input
      5. 2.2.5  Battery Ideal Diode-OR
      6. 2.2.6  Input and Battery Switchover Mechanics
      7. 2.2.7  LM74800 (U1) HGATE
      8. 2.2.8  Battery LM74800 HGATE
      9. 2.2.9  BQ25731 Design Considerations
      10. 2.2.10 BQ25731 Component Selection
      11. 2.2.11 ILIM Circuit
      12. 2.2.12 MCU and I2C Bus Design Considerations
      13. 2.2.13 MSP430FR2475
      14. 2.2.14 I2C Bus Overview
      15. 2.2.15 MSP430 Connectors
      16. 2.2.16 MSP430 Power Supply
      17. 2.2.17 Sensing Circuits
      18. 2.2.18 Current Sensing
      19. 2.2.19 Voltage Sensing
      20. 2.2.20 Input Comparators
      21. 2.2.21 Software Flow Chart
    3. 2.3 Highlighted Products
      1. 2.3.1 BQ25731
      2. 2.3.2 LM7480-Q1
      3. 2.3.3 LM74700-Q1
      4. 2.3.4 MSP430FR2475
      5. 2.3.5 PCA9546A
  8. 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 Adaptive Charge Current Limiting
      2. 3.3.2 Battery ORing System
      3. 3.3.3 Circuit Switchover From Adapter to Battery
  9. 4Design and Documentation Support
    1. 4.1 Design Files
      1. 4.1.1 Schematics
      2. 4.1.2 BOM
    2. 4.2 Documentation Support
    3. 4.3 Support Resources
    4. 4.4 Trademarks
  10. 5Revision History

3.3.3 Circuit Switchover From Adapter to Battery

This test is designed to demonstrate the adapter-to-battery switchover capabilities of the design. The test is run with 19 V on the input supply. The E-Load is then connected to the system rail and draws a constant current of 8 A. The input supply is then removed and the VIN, VSYS, and VBAT rails are monitored for the switchover timings. The test is then repeated while replacing the 19-V input supply with a 13-V supply to mimic a car charging adapter.

In Figure 3-1 through Figure 3-4, VIN is measured by CH1 (Blue), VBAT is measured by CH2 (Red) and, VSYS is measured by CH3 (Green). For these captures all channels are based at 0 V with no offset to better illustrate the switchover mechanism.

Figure 3-1 shows the 19 V to battery switchover with a time division of 200 μs. The minimum voltage at VSYS is 9.21 V. The approximate switchover timing is 10 μs and the VSYS rail has increased to 12.87 V by 20 μs after the switchover event.

GUID-20220516-SS0I-BLSQ-FJNL-KNGLFLN2SHKD-low.png Figure 3-1 19 V to Battery Switchover 200-μs Time Division

Figure 3-2 shows the 19 V to battery switchover with a time division of 20 μs. The minimum voltage at VSYS is 9.28 V. The approximate switchover timing is 10 μs and the VSYS rail has increased to 11.82 V by 10 μs after the switchover event.

GUID-20220516-SS0I-55WL-GT5X-CPZVDWFHT9J1-low.png Figure 3-2 19 V to Battery Switchover 20-μs Time Division

Figure 3-3 shows the 12 V to battery switchover with a time division of 100 μs. The minimum voltage at VSYS is 9.12 V. The approximate switchover timing is 10 μs and the VSYS rail has increased to 12.73 V by 20 μs after the switchover event.

GUID-20220516-SS0I-KPST-N8NN-CPXXVH1SQM2H-low.png Figure 3-3 12 V to Battery Switchover 10-μs Time Division

Figure 3-4 shows the 12 V to battery switchover with a time division of 20 μs. The minimum voltage at VSYS is 9.31 V. The approximate switchover timing is 10 μs and the VSYS rail has increased to 10.63 V by 10 μs after the switchover event.

GUID-20220516-SS0I-BF7V-FQQG-LCHZNX5VDCS3-low.png Figure 3-4 12 V to Battery Switchover 20-μs Time Division