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

2.2.20 Input Comparators

Two comparators are included to monitor VIN_FLT and PS_ID. These signals can be used to provide interrupt generation for the MCU when a specific type of adapter has been inserted or if an input adapter voltage threshold has been met. The TLV7031 nano-power, low-voltage comparator is used to provide a small footprint and low power draw while waiting for input events. Because these devices are powered by the battery when no input adapter is present, the ultra-low quiescent current of 315 nA is a key design feature.

GUID-20220516-SS0I-JH8Q-CB6F-TTN0SCHSCB1W-low.gif Figure 2-9 Input Capacitor Schematic

The voltage setting and hysteresis for these comparators can be calculated and adjusted according to
Equation 7.

V T H = V C C × R 100 R 97 | | R 101 + R 100
V T L = V C C × R 100 | | R 101 R 97 + R 100 | | R 101
V T H = 3.3   V × 82.5   k Ω 100   k Ω | | 3.57   M Ω + 82.5   k Ω = 1.51   V
Equation 7. V T L = 3.3   V × 82.5   k Ω | | 3.57   M Ω 100   k Ω + 82.5   k Ω | | 3.57   M Ω = 1.47   V