Agilex 5 GTS Reference Clock Buffer Protection

Hi sbj

Please find the below response on the question you have:

• The protection mechanism cannot be disabled or permanently overridden, and it automatically turns off the GTS input reference clock buffer when clock activity is absent or outside the 25–380 MHz detection range (Input Reference Clock Buffer Protection).
• The best way to avoid buffer shutoff is to keep the reference clock continuously present and toggling within the supported frequency range (Aging Issue on Unconnected/Used GTS Input Reference Clock Pins).
• If the clock stops, recovery requires either device reconfiguration or a buffer re-enable request through the register method or optional status/control ports (Input Reference Clock Buffer Protection).
• From Quartus Prime 24.3.1 onward, the device provides automatic aging protection, but user logic must still manually re-enable the buffer after the reference clock is restored (Aging Issue on Unconnected/Used GTS Input Reference Clock Pins).
• The recommended recovery sequence is to hold TX and RX PMA reset while the clock is absent, restore the clock, release the resets, request buffer turn-on, and verify the acknowledge and cleared failure status (GTS TX PLL Lock Status Guidelines).
• Enabling reference clock buffer recovery logic in the applicable GTS PHY or Ethernet IP exposes status and control ports that allow user logic to automate the recovery sequence (Low Latency 40G Ethernet IP Parameters).

Best Wishes

BB