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

ID 772538
Date 4/01/2024
Public
Document Table of Contents

7.2.3.3. Specific Pin Connection Requirements

PLL

For DDR5, you must constrain the PLL reference clock to the address and command lanes only.

  • You must constrain differential reference clocks to pin indices 10 and 11 in lane 2 when placing command address pins in lane 3 and lane 2.
  • You must constrain differential reference clocks to pin indices 10 and 11 in lane 4 when placing command address pins in lane 5 and lane 4.
  • The sharing of PLL reference clocks across multiple DDR5 interfaces is permitted within an I/O bank.
Note: Lane 3:0 is the bottom sub-bank and lane 7:4 is the top sub-bank.

OCT

For DDR5, you must constrain the RZQ pin to the address and command lanes only.
  • You must constrain RZQ to pin index 2 in lane 3 when placing command address pins in lane 3 and lane 2.
  • You must constrain RZQ to pin index 2 in lane 5 when placing command address pins in lane 5 and lane 4.
  • The sharing of RZQ across multiple DDR5 interfaces is permitted within an I/O bank.
Note: Lane 3:0 is the bottom sub-bank and lane 7:4 is the top sub-bank.

Address / Command / Parity

For DDR5, you must constrain the ALERT_N pin to the address and command lanes only.

  • You must constrain ALERT_N to pin index 1 in lane 3 when placing command address pins in lane 3 and lane 2.
  • You must constrain ALERT_N to pin index 1 in lane 5 when placing command address pins in lane 5 and lane 4.
Note: Lane 3:0 is the bottom sub-bank and lane 7:4 is the top sub-bank.

DQS/DQ/DM

For DDR5 x8 DQS/DQ/DM grouping, the following rules apply:

  • You may use pin indices 0, 1, 2, 3, 8, 9, 10, and 11 within a lane for DQ mode pins only.
  • You must use pin index 4 for the DQS_t pin only.
  • You must use pin index 5 for the DQS_c pin only.
  • You must ensure that pin index 7 remains unused. Pin index 7 is not available for use as a general purpose I/O.
  • You must use pin index 6 for the DM pin only.

For DDR5 x4 DQS/DQ/DM grouping, the following rules apply:

  • You may use pin indices 0, 1, 2, and 3 within a lane for DQ mode pins for the lower nibble only. Pin rotation within this group is permitted.
  • You must use pin index 4 for the DQS_t pin only of the lower nibble.
  • You must use pin index 5 for the DQS_c pin only of the lower nibble.
  • You may use pin indices 8, 9, 10, and 11 within a lane for the DQ mode pins only for the upper nibble. Pin rotation within this group is permitted.
  • You must use pin index 6 for the DQS_t pin only of the upper nibble.
  • You must use pin index 7 for the DQS_c pin only of the upper nibble.