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

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

7.6.8.1. DDR5 Discrete Component/Memory Down Topology: Single Rank x8 or x16, Dual Rank x8 or x16

Data Group includes Data Strobe and its complement (DQS and DQS#), Data (DQ), and Data Mask (DM). The connection from the FPGA to DRAM is point-to-point topology as shown in the figure below, for single rank.

Figure 40.  DRAM x8 or x16 (Single Rank)

Double rank topology has clamshell/fly-by configuration. For address, command, control and clock signals, a fly-by or clamshell topology is recommended to meet signal-integrity performance and for easier routing. The termination approach for DDR5 is through programmable ondie-termination (ODT). You can adjust the design topology based on the actual PCB design (single rank or dual rank).

Figure 41.  Single Rank, DRAM x 8 bits