KSZ9031RNX - What is the recommended series capacitive coupling for an external 25 MHz reference clock?

If the 25 MHz reference clock is provided externally, the XI input pin should have a minimum clock voltage peak-to-peak (VPP) swing of 2.5 V with reference to ground. If VPP is less than 2.5 V, the series capacitive coupling is recommended.

With capacitive coupling, the VPP swing can be down to 1.5 V. The maximum VPP swing is 3.3 V +5%. A series 0.1 µF capacitor can be used. The XI input pin has an internal voltage bias. No external voltage bias resistor is needed.

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