External Memory Interfaces Agilex™ 7 M-Series FPGA IP User Guide

ID 772538
Date 11/18/2024
Public
Document Table of Contents

8.5.6. General Notes for EMIF Routing Guidelines Tables

The following general notes apply to the EMIF routing guideline tables in subsequent topics.

  • All spacing requirements are the minimum requirement to be met on PCB in EMIF routing guidelines table.
  • In the routing guideline table, h represents the trace-to-nearest-reference-plane height or distance. Board designers should use the formula in the routing guidelines table to calculate the correct spacing requirements.
  • There is no differential impedance target for CLK and DQS. Board designers should follow the EMIF routing table and keep traces to be closely coupled.
  • The trace length and spacing in the guideline tables are based on FR-4 level PCB material and the PCB layout routing with the worst-case crosstalk. You should perform simulation if not following the requirements in the routing guidelines table.
  • In the routing guidelines tables, SL stands for strip line routing recommendations and US stands for upper surface (Microstrip) routing recommendations.
  • You need to design trace widths of BO, BO1, BO2 and BI, BI1, BI2 based on the actual PCB stack-up and PCB design. It would be better if trace widths of BO, BO1, BO2 and BI, BI1, BI2 can be designed closer to the target impedance of the M segment.
  • Include the FPGA package per-pin skew and PCB delay for skew matching.
  • Length matching on the Alert and Reset signals are not required.
  • Altera recommends that you perform skew matching in time (picoseconds).