External Memory Interfaces Agilex™ 7 F-Series and I-Series FPGA IP User Guide

ID 683216
Date 11/28/2024
Public
Document Table of Contents

3.1.4.1. Considerations for Designing DDR4 x72 Interface Together with an AVST x8/x16/x32 Configuration Scheme

The AVST x8 configuration scheme uses the dedicated SDM I/O pins and does not impact the number of DDR4 x72 interfaces that can be implemented on the device. An AVST x32 configuration scheme uses all four of the I/O lanes in the top sub-bank in Bank 3A. This breaks the contiguity requirement and reduces the maximum number of DDR4 x72 interfaces that can be supported on the device.

However, the AVST x16 configuration scheme only uses three I/O Lanes. I/O Lane 2 in the top sub-bank in Bank 3A is available for EMIF purposes and maintains the contiguity requirement. This I/O Lane can be used as a DQ Lane for EMIF purposes.

Figure 49. Pin Assignment in Top Sub-bank in Bank 3A for AVST x16 Configuration Scheme

To implement a DDR4 x72 interface using the top sub-bank in Bank 3A together with an AVST x16 configuration scheme, you must use the address/command scheme with four IO Lanes. The following figure shows the I/O lane assignment for implementing a DDR4 x 72 interface in such a scenario.

Figure 50. I/O Lane Assignment for Implementing AVST x16 and DDR4 x72 Interface Using Bank 3A

The following table shows the maximum number of DDR4 x72 interfaces that can be supported with different AVST configuration schemes.

Table 5.  DDR x72 EMIF With AVST and Address/Command Scheme with 4 I/O Lanes
Device/Package 1× DDR4 x72 2× DDR4 x72 3× DDR4 x72 4× DDR4 x72 6× DDR4 x72 8× DDR4 x72
AGF014/AGF012, R24A/R24B AVST 8, 16, 32 AVST 8, 16, 32 AVST 8, 16, 32 AVST 8, 16 N/A N/A
AGF027/AGF022, R24C AVST 8, 16, 32 AVST 8, 16, 32 AVST 8, 16, 32 AVST 8, 16 N/A N/A
AGF027/AGF022, R25A AVST 8, 16, 32 AVST 8, 16, 32 N/A N/A N/A N/A
AGF027/AGF022, R31C AVST 8, 16, 32 AVST 8, 16, 32 AVST 8, 16, 32 AVST 8 N/A N/A
AGI027/AGI022, R29A AVST 8, 16, 32 AVST 8, 16, 32 AVST 8, 16, 32 AVST 8 N/A N/A
AGI027/AGI022, R31B AVST 8, 16, 32 AVST 8, 16, 32 AVST 8, 16, 32 AVST 8 N/A N/A
AGF019/AGF023, R25A AVST 8, 16, 32 AVST 8, 16 N/A N/A N/A N/A
AGF006/AGF008, R16A AVST 8, 16, 32 N/A N/A N/A N/A N/A
AGF006/AGF008, R24C AVST 8, 16, 32 AVST 8, 16, 32 N/A N/A N/A N/A
AGF012/AGF014, R24C AVST 8, 16, 32 AVST 8, 16, 32 AVST 8, 16, 32 AVST 8, 16 N/A N/A
AGF019/AGF023, R24C AVST 8, 16, 32 AVST 8, 16 N/A N/A N/A N/A
AGI019/AGI023, R31B AVST 8, 16, 32 AVST 8, 16 N/A N/A N/A N/A
AGI019/AGI023, R18A AVST 8, 16, 32 AVST 8, 16 N/A N/A N/A N/A
AGI035/AGI040, R39A AVST 8, 16, 32 AVST 8, 16, 32 N/A N/A N/A N/A
AGI019/AGI023, R31C AVST 8, 16, 32 AVST 8, 16 N/A N/A N/A N/A
AGI027, R29B AVST 8, 16, 32 AVST 8, 16, 32 AVST 8, 16, 32 AVST 8 N/A N/A
AGI041, R29D AVST 8, 16, 32 AVST 8, 16, 32 AVST 8, 16, 32 AVST 8 N/A N/A
AGI022/AGI027, R31A AVST 8, 16, 32 AVST 8, 16, 32 AVST 8, 16, 32 AVST 8 N/A N/A
AGF019/AGF023, R31C AVST 8, 16, 32 AVST 8, 16 N/A N/A N/A N/A
AGI041, R31B AVST 8, 16, 32 AVST 8, 16, 32 AVST 8, 16, 32 AVST 8 N/A N/A
Table 6.  DDR x72 EMIF With AVST and Address/Command Scheme with 3 I/O Lanes
Device/Package 1× DDR4 x72 2× DDR4 x72 3× DDR4 x72 4× DDR4 x72 6× DDR4 x72 8× DDR4 x72
AGF014/AGF012, R24A/R24B AVST 8, 16, 32 AVST 8, 16, 32 AVST 8, 16, 32 AVST 8 N/A N/A
AGF027/AGF022, R24C AVST 8, 16, 32 AVST 8, 16, 32 AVST 8, 16, 32 AVST 8 N/A N/A
AGF027/AGF022, R25A AVST 8, 16, 32 AVST 8, 16, 32 AVST 8, 16, 32 AVST 8, 16, 32 N/A N/A
AGF027/AGF022, R31C AVST 8, 16, 32 AVST 8, 16, 32 AVST 8, 16, 32 AVST 8 N/A N/A
AGI027/AGI022, R29A AVST 8, 16, 32 AVST 8, 16, 32 AVST 8, 16, 32 AVST 8 N/A N/A
AGI027/AGI022, R31B AVST 8, 16, 32 AVST 8, 16, 32 AVST 8, 16, 32 AVST 8 N/A N/A
AGF019/AGF023, R25A AVST 8, 16, 32 AVST 8, 16, 32 AVST 8, 16, 32 N/A N/A N/A
AGF006/AGF008, R16A AVST 8, 16, 32 AVST 8, 16, 32 N/A N/A N/A N/A
AGF006/AGF008, R24C AVST 8, 16, 32 AVST 8, 16, 32 AVST 8, 16, 32 AVST 8 N/A N/A
AGF012/AGF014, R24C AVST 8, 16, 32 AVST 8, 16, 32 AVST 8, 16, 32 AVST 8, 16, 32 N/A N/A
AGF019/AGF023, R24C AVST 8, 16, 32 AVST 8, 16, 32 AVST 8, 16, 32 N/A N/A N/A
AGI019/AGI023, R31B AVST 8, 16, 32 AVST 8, 16, 32 AVST 8, 16, 32 N/A N/A N/A
AGI019/AGI023, R18A AVST 8, 16, 32 AVST 8, 16, 32 AVST 8, 16, 32 N/A N/A N/A
AGI035/AGI040, R39A AVST 8, 16, 32 AVST 8, 16, 32 AVST 8, 16, 32 AVST 8 N/A N/A
AGI019/AGI023, R31C AVST 8, 16, 32 AVST 8, 16, 32 AVST 8, 16, 32 N/A N/A N/A
AGI027, R29B AVST 8, 16, 32 AVST 8, 16, 32 AVST 8, 16, 32 AVST 8 N/A N/A
AGI041, R29D AVST 8, 16, 32 AVST 8, 16, 32 AVST 8, 16, 32 AVST 8 N/A N/A
AGI022/AGI027, R31A AVST 8, 16, 32 AVST 8, 16, 32 AVST 8, 16, 32 AVST 8 N/A N/A
AGF019/AGF023, R31C AVST 8, 16, 32 AVST 8, 16, 32 AVST 8, 16, 32 N/A N/A N/A
AGI041, R31B AVST 8, 16, 32 AVST 8, 16, 32 AVST 8, 16, 32 AVST 8 N/A N/A

Restriction for using JB26, JH26, JP26 and JL27 on AGI041, Package R29D

You must adhere to these guidelines when using pin JB26, JH26, JP26 and JL27 on AGI041, package R29D, to reduce crosstalk coupling from adjacent I/O pins (JP26 and JL27) to R-tile REFCLK pins (JB26 and JH26).

Figure 51. Recommended PCB Layout for Using JB26, JH26, JP26 and JL27

Follow these guidelines:

  • Implement one of the 3 layout options shown in the above figure.
  • Route DDR/IO (JP26, JL27) at deep layer, L16 and R-tile REFCLK at shallow layer, L3. This is only applicable to pin JB26, JH26, JP26 and JL27.
  • Keep maximum R-tile REFCLK route length < 3.7 inches.
  • Refer to routing recommendations for REFCLK generator from manufacturer (if applicable).
  • Keep at least 5xH separation between 100MHz R-tile REFCLK to DDR4/other GPIO signals.
    Figure 52. Separation between R-Tile REFCLK to DDR4/GPIO signals
    Note: H is the closest distance measuring from trace to ground reference plane in Z-direction.