TIDUF26 june   2023 BQ24072 , LMR36520 , TLV62568 , TPS2116

 

  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 Design Considerations
      1. 2.2.1 24 VAC to DC Rectification
      2. 2.2.2 eFuse Protection
      3. 2.2.3 5-V Rails
        1. 2.2.3.1 LMR36520 Voltage Rail
        2. 2.2.3.2 USB Power Input
      4. 2.2.4 Power Source ORing
      5. 2.2.5 Battery Management
      6. 2.2.6 3.3-V Power Rail
      7. 2.2.7 Power Rail Current Sensing
      8. 2.2.8 Backlight LED Driver
      9. 2.2.9 BoosterPack Overview
    3. 2.3 Highlighted Products
      1. 2.3.1 LMR36520
      2. 2.3.2 TPS2116
      3. 2.3.3 TLV62568
      4. 2.3.4 INA2180
      5. 2.3.5 TPS92360
      6. 2.3.6 TPS2640
      7. 2.3.7 BQ24072
  9. 3Hardware, Software, Testing Requirements, and Test Results
    1. 3.1 Hardware Requirements
    2. 3.2 Test Setup
    3. 3.3 Test Results
      1. 3.3.1  24-VAC Start-Up and Shutdown
      2. 3.3.2  USB Start-Up and Shutdown
      3. 3.3.3  ORing
      4. 3.3.4  LMR36520
      5. 3.3.5  TLV62568 Transient Response
      6. 3.3.6  BM24072 Transient Response
      7. 3.3.7  TLV62568 (3V3 Power Rail)
      8. 3.3.8  LMR36520 (LMOut Power Rail)
      9. 3.3.9  BM24072 (BMOut Power Rail)
      10. 3.3.10 Reference
        1. 3.3.10.1 TLV62568
        2. 3.3.10.2 LMR36520
  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

2.2.3.2 USB Power Input

Like the LMR36520 device, the USB power input is capable of powering the entire system. The USB can serve as a backup power source, be used for debugging other aspects of the systems in the product, or be used to charge the battery in case the main 24 VAC is not available. The TIDA-010932 does not supply power to USB; it only sinks power from a USB host. ESD and overvoltage protection are included as shown in Figure 2-6.

GUID-20230608-SS0I-QXVN-D6CR-LT7XVZLPCN47-low.png Figure 2-6 USB Implementation

This reference design uses USB 2.0, and therefore assumes the maximum current that can be pulled from a USB host is 500 mA. USB 2.0 specification allows a tolerance of 5% from the nominal 5 V, thereby giving a host voltage range of 4.75 V to 5.25 V. Furthermore, USB 2.0 specification also allows the worst case voltage drop across all cables and connectors to bring the total voltage at load to 4.35 V. The TIDA-010932 is designed to accommodate USB 2.0 at the worst-case specification.

R29 and C6 provide a snubber circuit to the USB Vbus, reducing the overshoot and ringing caused by the cable inductance and capacitive load resonance. The snubber circuit must be tuned for each system design; therefore, the snubber component values used in the TIDA-010932 must be tested when designed into a new system and the values must be changed appropriately.