GTS Transceiver PHY User Guide: Agilex™ 3 FPGAs and SoCs

ID 848344
Date 8/04/2025
Public
Document Table of Contents

3.9.8. TX PLL Lock Loss

Figure 51. Reset Sequence for TX PLL Lock Loss
The figure above illustrates the sequence in the event of a TX PLL lock loss:
  1. o_tx_pll_locked deasserts, indicating that the TX PLL has lost lock from the reference clock.
  2. o_tx_ready deasserts, indicating that the datapath is no longer operational.
  3. Monitor the TX PLL lock status by following the guidelines in the Guidelines for Obtaining the Real-Time GTS TX PLL Lock Status section.
  4. Assert i_tx_reset if you detect a loss of lock for the TX PLL.
  5. o_tx_ready deasserts, indicating that the TX datapath is no longer operational.
  6. o_tx_pll_locked deasserts.
  7. o_tx_reset_ack asserts, indicating that the datapaths are in reset. o_tx_reset_ack stays asserted until i_tx_reset deasserts.
  8. Check the input reference clock buffer's status and re-enable it if it is turned off, as described in the Re-enabling the Reference Clock Buffers section. You can then deassert the i_tx_reset to bring the TX out of reset.
  9. o_tx_pll_locked asserts as the TX PLL locks to the reference clock.
  10. o_tx_ready asserts, indicating that the datapath is operational and at the same time you can restart monitoring of the TX PLL lock status by following the guidelines in the Guidelines for Obtaining the Real-Time GTS TX PLL Lock Status section.