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

2.3.6 TPS746-Q1 (PD PHY 3.3V Rail LDO)

The TPS746-Q1 is a 1A, ultra-low-dropout regulator (LDO) with power-good functionality. This device is available in a small 6-pin, 2mm × 2mm WSON package and a small 8-pin, 3mm × 3mm VSON package with wettable flanks to facilitate optical inspection. The TPS746-Q1 consumes low quiescent current and provides fast line and load transient performance.

The TPS746-Q1 is a flexible device for post-regulation by supporting an input voltage range from 1.5V to 6.0V and an externally adjustable output range of 0.55V to 5.5V. The device also features fixed output voltages for powering common voltage rails.

The TPS746-Q1 has a power-good (PG) output that monitors the voltage at the feedback pin to indicate the status of the output voltage. The EN input and PG output can be used for sequencing multiple power supplies in the system.

The TPS746-Q1 is stable with small ceramic output capacitors, allowing for a small overall design size. A precision band-gap and error amplifier provides high accuracy of ±0.85% (max) at 25°C and ±1.5% (max) overtemperature. This device includes integrated thermal shutdown, current limit, and undervoltage lockout (UVLO) features. The TPS746-Q1 has an internal foldback current limit that helps reduce the thermal dissipation during short-circuit events.