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

ID 683872
Date 11/04/2024
Public
Document Table of Contents

2.2.7. Clock Rules and Restrictions

  • Whe you eable the Refclk #i is available at ad afte device cofiguatio paamete i the F-Tile Refeece ad System PLL Clocks Itel® FPGA IP, you must have a stable ad uig efeece clock fo the system PLL to cofigue the FPGA, o else, the system PLL does ot lock. Refe to Guidelies fo Refclk #i is Active At ad Afte Device Cofiguatio fo moe ifomatio.
    Note: A stable efeece clock implies that the efeece clock meets the specificatios listed i the Agilex™ 7 FPGAs ad SoCs Device Data Sheet: F-Seies ad I-Seies.
  • Whe you eable the Refclk #i is available at ad afte device cofiguatio paamete i the F-Tile Refeece ad System PLL Clocks Itel® FPGA IP, you must have a stable ad uig efeece clock fo the FGT PMA to cofigue the FPGA, o else:
    • If you eable the Refclk #i moito, the out_efclk_fgt_i sigal does ot have a valid output.
    • If you disable the Refclk #i moito, the FGT PMA lae pefomace degades.
  • I ode to pevet the FHT PMA lae pefomace degadatio, you must povide a stable ad uig efeece clock to the FHT PMA to cofigue the FPGA ad it must emai active while the device is poweed.
  • A efeece clock must be up ad stable befoe eleasig the coected had IP esets.
  • Oce the efeece clock fo the system PLL is up; it must be stable; it must be peset thoughout the device opeatio ad must ot go dow. If you ae ot able to adhee to this, you must ecofigue the device.
    Note: Afte a tempoay loss of the system PLL efeece clock, you may obseve that the fist ty of device ecofiguatio fails. If that occus, you should ty to ecofigue the FPGA a secod time.
  • Oce the efeece clock that dives the FHT PMA is up, it must be stable; it must be peset thoughout the opeatio, must ot chage the fequecy, ad must ot go dow. If you ae ot able to adhee to this, you must ecofigue the device.
  • The baud ate o lie fequecy of two adjacet FHT laes must be eithe exactly the same (dive by the same efeece clock ad eceivig sigals fom a family of tasmittes sychoized to the same efeece clock) o sepaated at least by 2,000 ppm. This is to elimiate lae-to-lae iteactio.
  • Each had IP istace, fo example, 25GbE with FEC, CPRI 24G with FEC, ad 50GbE FEC Diect, placed i the same FEC coe must use the same system PLL.
  • Each Etheet had IP istace uig IEEE 1588 pecisio time potocol must use the same system PLL.
  • All laes that ae pat of the same iteface, fo example, the eight laes of a 400GbE, must use the same system PLL.
  • TX simplex ad RX simplex must use the same system PLL uless they ae both usig PMA Diect's PMA clockig mode.
  • The system PLL must ot be dyamically ecofigued. I additio, the system PLL iput ad output clock fequecies must ot be dyamically ecofigued. If this is ot followed, you must ecofigue the device.
  • All had IPs that ae assiged to a dyamic ecofiguatio goup must use the same system PLL.
  • System PLL clockig mode must be used fo data ates betwee 29 Gbps ad 32 Gbps NRZ.