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

ID 772538
Date 11/18/2024
Public

A newer version of this document is available. Customers should click here to go to the newest version.

Document Table of Contents

7.6.7. 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 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).