SNLA452 August   2025 DP83TD510E

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Troubleshooting the Application
    1. 2.1 Schematic and Layout Checklist
    2. 2.2 Component Checklist
    3. 2.3 Device Health Checks
      1. 2.3.1 Check Voltage Supply Pins
      2. 2.3.2 Probe the RST_N Pin
      3. 2.3.3 Probe the CLKOUT Pin
      4. 2.3.4 Probe the SMI Pins
    4. 2.4 Read and Check Register Values
    5. 2.5 Verifying Strap Configuration
    6. 2.6 Loopbacks
    7. 2.7 MDI Health Checks
      1. 2.7.1 Link Up Common Issues
      2. 2.7.2 Transmit Level
        1. 2.7.2.1 Change Transmit Level
      3. 2.7.3 Time-Domain Reflectometry
      4. 2.7.4 Signal Quality Check
      5. 2.7.5 MDI Test Modes
    8. 2.8 MII Health Checks
      1. 2.8.1 RGMII
      2. 2.8.2 RMII
      3. 2.8.3 MII
  6. 3Summary
  7. 4References

2.3.3 Probe the CLKOUT Pin

The CLKOUT/LED_1 Pin (Pin 30) is an Input/Output GPIO pin which defaults to output a reference clock signal, which can be used to supply a clock to any other devices on the board. This reference clock is of the utmost importance to maintain proper operation of the PHY. Failure to meet the requirements in the data sheet can lead to bit errors, read or write issues, and in some cases, total non-operation of the PHY.

Verify that the input clock, crystal or oscillator, is available at power-up.

This clock signal is a buffered representation of the input clock crystal or oscillator. If a crystal is being used, do not probe the crystal directly, since the change in capacitance due to the probe can change the behavior of the crystal.

Make sure that this CLKOUT signal is within the ppm requirement.

CLKOUT Signal Figure 2-1 CLKOUT Signal