TIDUF49 February   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 System Block Diagram
    2. 2.2 Design Considerations
    3. 2.3 Highlighted Products
      1. 2.3.1 DP83RG720S-Q1 (Automotive SPE PHY)
      2. 2.3.2 TPS1HTC30-Q1 (HSS)
      3. 2.3.3 LM5157x-Q1 and LM5158x-Q1 (PSE PoDL Boost Converter)
      4. 2.3.4 LMR38020-Q1 (PD PoDL Buck Converter)
      5. 2.3.5 TPS629210-Q1 (PD 5.0V Rail Buck Converter)
      6. 2.3.6 TPS746-Q1 (PD PHY 3.3V Rail LDO)
      7. 2.3.7 TPS745-Q1 (PSE and PD PHY 1.0V Rail LDO)
  9. 3System Design Theory
    1. 3.1 System Design Consideration for TIDA-020060 (PSE)
      1. 3.1.1 Ethernet PHY
      2. 3.1.2 PHY Power Supply
      3. 3.1.3 PSE Specific PoDL Power Supply
    2. 3.2 System Design Consideration for TIDA-020061 (PD)
    3. 3.3 General Design Consideration for PoDL Coupling Decoupling Network
  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
  11. 5Design and Documentation Support
    1. 5.1 Design Files
      1. 5.1.1 Schematics
      2. 5.1.2 BOM
      3. 5.1.3 PCB Layout Recommendations
    2. 5.2 Tools and Software
    3. 5.3 Documentation Support
    4. 5.4 Support Resources
    5. 5.5 Trademarks
  12. 6About the Author

2.3.4 LMR38020-Q1 (PD PoDL Buck Converter)

The LMR38020-Q1 synchronous buck converter is designed to regulate over a wide input voltage range, minimizing the need for external surge suppression components. The LMR38020-Q1 operates during input voltage dips as low as 4.2V, at nearly 100% duty cycle if needed, making the device an excellent choice for 48V battery automotive applications and MHEV or EV systems.

The LMR38020-Q1 uses precision enable to provide flexibility by enabling a direct connection to the wide input voltage or precise control over device start-up and shutdown. The power-good flag, with built-in filtering and delay, offers a true indication of system status, eliminating the need for an external supervisor. The device incorporates pseudorandom spread spectrum for minimal EMI and switching frequency can be configured between 200kHz and 2.2MHz to avoid noise sensitive frequency bands. In addition, the frequency can be selected for improved efficiency at low operating frequency or smaller design size at high operating frequency.

The device has built-in protection features such as cycle-by-cycle current limit, hiccup mode short-circuit protection, and thermal shutdown in case of excessive power dissipation. The LMR38020-Q1 is qualified to automotive AEC-Q100 grade 1 and is available in an 8-pin HSOIC PowerPAD integrated circuit package.