DDR4_SODIMM_SPEC.pdf

3.1 DDR4 SO-DIMM Connector Pin Assignments .....................................................................................10

4 Power Details ................................................................................................................... 12

4.1 DIMM Voltage Requirements ................................................................................................................12

4.2 Rules for Power-Up Sequence..............................................................................................................13

4.3 Feed Through Voltage (VFT).................................................................................................................13

5 Component Details.......................................................................................................... 14

5.1 Component Types and Placement .......................................................................................................17

5.2 Decoupling Guidelines ..........................................................................................................................17

6 DIMM Design Details ....................................................................................................... 18

6.1 Signal Groups ........................................................................................................................................18

6.3.5 Load/Delay Compensation ............................................................................................21

6.3.6 Data and Strobe Group .................................................................................................22

6.3.7 ALERT_n Wiring............................................................................................................22

6.3.8 Via Compensation .........................................................................................................23

6.3.9 Plane Referencing.........................................................................................................24

6.4 Rules for Higher Speed (2666 Mb/s or Higher)....................................................................................25

6.5 Address Mirroring..................................................................................................................................26

6.6 DIMM Routing Space Constraints ........................................................................................................27

6.7 DIMM Physical Requirements...............................................................................................................28

6.7.1 Via Size .........................................................................................................................28

6.8 Reference Stackups...............................................................................................................................29

6.9 Impedance Targets ................................................................................................................................31

6.10 SPD Wiring and Placement ...................................................................................................................32

6.11 DQ Mapping to Support CRC................................................................................................................33

7 Serial Presence Detect Component Specification........................................................ 36

7.1 Serial Presence Detect Definition.........................................................................................................36

8 Product Label................................................................................................................... 38

8.1 DDR4 DIMM Label Format for DRAM-only module types...................................................................38

8.2 DDR4 DIMM Label Format for Hybrid module types...........................................................................43

9 JEDEC Process................................................................................................................ 50

This specification defines the electrical and mechanical requirements for 260 pin, 1.2 V (VDD), Small Outline,

Double Data Rate, Synchronous DRAM Dual In-Line Memory Modules (DDR4 SDRAM SO-DIMMs). These

DDR4 SO-DIMMs are intended for use as main memory when installed in PCs, laptops and other systems.

Reference design examples are included which provide an initial basis for DDR4 SO-DIMM designs.

Modifications to these reference designs may be required to meet all system timing, signal integrity and

thermal requirements for PC4-1600, PC4-1866, PC4-2133, PC4-2400, PC4-2666 and PC4-3200 support. All

DDR4 SO-DIMM implementations must use simulations and lab verification to ensure proper timing