F-tile Architecture and PMA and FEC Direct PHY IP User Guide

ID 683872
Date 6/24/2022
Public

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4.5. Guidelines to Indicate all System PLL Reference Clocks are Ready

When the system PLL #N (N = 0, 1, 2) mode is enabled but the reference clock is not available or stable at device programming time, you must set the Refclk is available at power-on parameter to Off. When the system PLL #N (N = 0, 1, 2) mode is disabled, you can ignore the reference clock.

For all enabled system PLLs that have the parameter Refclk is available at power-on set to On, you must provide stable reference clocks for the system PLLs at device programming time.

For all enabled system PLLs that have the parameter Refclk is available at power-on set to Off, system PLL does not start locking until you perform the PMA Avalon® memory-mapped interface write operations signaling that all reference clocks are ready.

If any one of the three system PLLs on the same F-tile is enabled and has the Refclk is available at power-on parameter set to Off, the device programming takes longer and all non PCIe channels on this F-tile stay reset until you perform the PMA Avalon® memory-mapped interface write operations signaling that all reference clocks are ready.