Intel® Arria® 10 Transceiver PHY User Guide

ID 683617
Date 9/15/2023
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6.11.2.2. fPLL Reference Clock Switching

You can use the reconfiguration interface on the fPLL instance to specify which reference clock source drives the fPLL. The fPLL supports clocking by up to five different reference clock sources. The flow to select between the different reference clock sources is independent of the number of transmitter PLLs specified in the reconfiguration interface.

Before initiating a reference clock switch, ensure that your fPLL instance defines more than one reference clock source. Specify the Number of PLL reference clocks parameter on the PLL tab during fPLL parameterization.

The following table shows the addresses and bits for switching between fPLL reference clock inputs. The number of exposed pll_refclk ports varies according to the number of reference clocks you specify. Use the fPLL reconfiguration interface for this operation.