3.1.3 Clocks

The KSZ8081RNB uses a clock source to perform both 100BASE-TX and MII communication. If the clock isn’t operating per device requirements (incorrect frequency, amplitude, or jitter exceeds limits), it is expected that KSZ8081RNB connectivity will be impacted. Probe the clock and verify:

  • Frequency (including variation)
  • Amplitude
  • Duty Cycle
Note: The KSZ8081RNB also allows for a standard crystal or single-ended clock source and multiple frequencies. If using a crystal, ensure the loading capacitors meet the crystal’s own specifications. If using a single-ended clock source, ensure that the XO pin on KSZ8081RNB is left floating.