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

4.3 Test Setup

Figure 4-1 shows a block diagram of the test setup.

GUID-20240212-SS0I-4HLJ-JL0F-6X9SGZ26QKPB-low.svgFigure 4-1 Test Setup of SQI Test

Table 4-2 details the test conditions used.

Table 4-2 SQI Test Conditions
TEST CONDITIONS VALUE
CDN #2, #3, #4, #5
VPoDL 12V, 24V, 48V
IPoDL Maximum rated current of CDN, pulsed current profile
Cable length 15m
Temperature Room temperature
Test duration 10 minutes

This tests evaluates the test parameter SQI. During the test, the PHY continuously measures the mean square error (MSE) of the signal and stores the result in a register. This MSE register of the PHY is logged during the test. After the test is completed, the MSE register log is converted to the signal-to-noise ratio (SNR).

To determine if the test has passed or failed, Table 4-3 is used.

Table 4-3 SNR Limits
SQI VALUESNR VALUEBER FOR AWG NOISE MODEL
SQI = 7SNR > = 24dBBER <10-10errorbit
Passing IEEE limit
SQI = 624dB > SNR > = 23dB
SQI = 523dB > SNR > = 22dB
SQI = 422dB > SNR > = 21dB
SQI = 321dB > SNR > = 20dB
SQI = 220dB > SNR > = 19dBBER >10-10errorbit
Failing IEEE limit
SQI = 119dB > SNR > = 18dB
SQI = 0SNR < 18dB