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

General Design Consideration for PoDL Coupling Decoupling Network

There are two main factors to consider when selecting a CDN: Ethernet speed and power consumption of the PD. Table 3-3 shows each Ethernet PHY with the corresponding Ethernet standard and data frequency.

Table 3-3 Ethernet Signal Frequencies
Ethernet PHY IEEE STANDARD DATA RATE SYMBOL RATE
10Base-T1S 10Mb/s 12.5MHz
DP83TC812-Q1 100Base-T1 100Mb/s 66.6MHz
DP83TC813-Q1
DP83TC814-Q1
DP83TG720-Q1 1000Base-T1 1000Mb/s 750MHz

Each PoDL CDN has a maximum current that it can support while maintaining the required impedance based on the saturation characteristics of the components. Inductors do not behave in a flawless manner, the inductors dissipate heat, pass very high frequencies and saturate when too much current is passed through. All components and cables have parasitic capacities and impedances throughout the entire circuit. Knowing the maximum power the PD draws and selecting a CDN solution that can deliver that power for a given PoDL voltage is important. Calculate the maximum power as the worst-case scenario of power consumption on the PD side of the link. Highest power consumption refers to a period where, for example, the radar is chirping and all other remote devices are operating. The user need to select a PoDL network capable of supplying enough current for the PD.

Table 3-4 provides CDN solution suggestions. TI recommends selecting one of the networks based on the desired frequency range, current rating, and temperature.

Table 3-4 CDN Filter Solution for PoDL
VENDOR CDN FILTER
SOLUTION
Ethernet
SPEED
COMPONENTS CURRENT
RATING
TEMPERATURE
RATING
TDK 2 100Base-T1 CMC: ACT1210L-201-2P-TL00
DMI: PID77S-180M
1350mA 150°C
MuRata 3 1000Base-T1 CMC: DLW32MH101XT2
DMI: LQH32NH3R3J23
425mA 125°C
TDK 4 1000Base-T1 CMC: ACT1210G-800-2P-TL10
DMI: ADL32VHR-3R9M
540mA 150°C
TDK 5 1000Base-T1 CMC: ACT1210G-800-2P-TL10
DMI: ADM70S-2R6
1500mA 150°C