JESD305-R8-RCE_v12022DDR5RDIMMStandardAnnexE.pdf

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DDR5 RDIMM标准是JEDEC固态技术协会（JEDEC Solid State Technology Association）发布的一份重要的行业规范，主要用于定义双倍数据速率第五代同步动态随机存取内存（DDR5 Registered Dual In-line Memory Modules，RDIMM）的技术规格。这份标准的Annex E详细阐述了DDR5 RDIMM在设计、制造、互操作性和性能方面的要求，以确保内存模块的稳定性和可靠性。 DDR5是内存技术的最新迭代，相比于DDR4，它带来了显著的性能提升和能效改进。主要知识点包括： 1. **速度提升**：DDR5内存的起始频率高于DDR4，提供了更快的数据传输速度，使得系统处理大量数据时更高效。随着技术的演进，DDR5的频率将进一步提升，以满足高性能计算和大数据应用的需求。 2. **电压降低**：尽管速度提升，但DDR5降低了工作电压，这有助于减少功耗并改善整体系统能效，尤其对于移动设备和服务器平台至关重要。 3. **Bank Group架构**：DDR5引入了Bank Group设计，将传统的Bank结构分成更小的单元，增强了并发操作能力，从而提高了内存带宽和响应速度。 4. **On-Die Termination (ODT)**：DDR5内存芯片内部集成了片上终结器（ODT），减少了信号反射，改善了信号完整性，同时降低了主板上的外部组件需求。 5. **错误校验增强**：DDR5支持更高级的错误检测和纠正机制，如增强型ECC（Error Correction Code），可以发现并修复更多类型的内存错误，提高数据的准确性和系统的稳定性。 6. **电源管理集成**：每个DDR5 DIMM上包含两个独立的电源管理集成电路（PMIC），提供更精确的电压控制，同时增强了电源故障恢复能力。 7. **寄存器增强**：DDR5 RDIMM的寄存器（Register）功能得到增强，能够更好地管理和协调多个DRAM芯片之间的通信，减少延迟并提高系统性能。 8. **模块容量**：DDR5内存模块的容量比DDR4有显著增加，这得益于新的芯片设计和封装技术，为数据中心和服务器提供了更大的内存扩展空间。 9. **热管理**：DDR5标准可能包含了针对热管理的新规定，以确保在高负载下内存模块的可靠运行。 10. **兼容性与升级**：虽然DDR5带来了显著的性能提升，但它与DDR4不兼容，需要新的主板接口和控制器支持。因此，升级到DDR5需要全面的硬件更新。 JESD305-R8-RCE_v1 2022 DDR5 RDIMM Standard Annex E是JEDEC为推动DDR5内存技术标准化和行业采纳而制定的关键文档，它涵盖了从物理层接口到功能特性的所有关键细节，旨在促进内存产业的持续发展和创新。

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JEDEC

STANDARD

DDR5 RDIMM Standard Annex E

JESD305-R8-RCE

Version 1.0

APRIL 2022

JEDEC SOLID STATE TECHNOLOGY ASSOCIATION

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JEDEC

JEDEC Standard No. 305-R8-RCE

Version 1.0

-i-

DDR5 RDIMM STANDARD ANNEX E

Contents

Page

1 Scope ................................................................................................................................................. 1

2 DDR5 Registered DIMM Design File .............................................................................................. 1

3 Module Configuration ....................................................................................................................... 1

4 SDRAM Configuration ..................................................................................................................... 2

5 Supported Speeds .............................................................................................................................. 2

6 Design Deviations ............................................................................................................................. 2

7 General Layout .................................................................................................................................. 3

8 Functional Block Diagram ................................................................................................................ 4

9 SMBus Net Structures ....................................................................................................................... 8

10 Clock Input Net Structure ................................................................................................................. 8

11 Register Clock Output Net Structure ................................................................................................ 9

12 Data Net Structure – DQ, CB, DQS_t, and DQS_c ........................................................................ 10

13 Post Register Address and Command Net Structure Routing ......................................................... 12

14 Post Register Control Net Structure Routing .................................................................................. 13

15 Pre-Register Address, Command, Control, and Parity Net Structure Routing ............................... 14

16 DIMM Impedance Profile ............................................................................................................... 15

17 RESET_n and QRST_n Net Structure Routing .............................................................................. 16

18 ALERT_n Output Net Structure Routing ........................................................................................ 16

19 DERROR_in_n Net Structure Routing ........................................................................................... 17

20 Function Control Word Programming............................................................................................. 18

21 Cross Section Recommendations .................................................................................................... 19

Tables

Table 1 — DDR5 Registered DIMM Design File ............................................................................................... 1

Table 2 — Module Configuration ........................................................................................................................ 1

Table 3 — SDRAM Configuration ...................................................................................................................... 2

Table 4 — Supported Speeds ............................................................................................................................... 2

Table 5 — Design Deviations .............................................................................................................................. 2

Table 6 — SMBus Net Structures ........................................................................................................................ 8

Table 7 — Clock Lengths for Register Input Net Structures ............................................................................... 8

Table 8 — Trace Lengths for Register Clock Output to SDRAM Load Net Structures ...................................... 9

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JEDEC