DDR4 Overview

With DDR3 reaching its limits in a world that demands higher performance and increased bandwidth, a new generation of DDR SDRAM has arrived. DDR4 delivers higher performance, higher DIMM capacities, improved data integrity and lower power consumption.

Achieving more than 2Gbps per pin and consuming less power than DDR3L (DDR3 Low Voltage), DDR4 provides up to 50 percent increased performance and bandwidth while decreasing the power consumption of your overall computing environment. This represents a significant improvement over previous memory technologies and a power savings up to 40 percent.

In addition to optimized performance and greener, low-cost computing, DDR4 also provides cyclic redundancy checks (CRC) for improved data reliability, on-chip parity detection for integrity verification of ‘command and address’ transfers over a link, enhanced signal integrity and other robust RAS features.

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Technology at a Glance
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DDR4 Details

Please note that there are subtle differences between DDR3 and DDR4 modules.

Key notch difference

The key notch on a DDR4 module is in a different location from the key notch on a DDR3 module. Both notches are located on the insertion edge but the notch location on the DDR4 is slightly different, to prevent it the module from being installed into an incompatible board or platform.

Increased thickness

DDR4 modules are slightly thicker than DDR3, to accommodate more signal layers.

Curved edge

DDR4 modules feature a curved edge to help with insertion and alleviate stress on the PCB during memory installation.

Specifications at a Glance
Description DDR3 DDR4 Advantage
Chip Densities 512Mb-8Gb 4Gb-16Gb Larger DIMM Capacities
Data Rates 800Mb/s – 2133Mb/s 1600Mb/s – 3200Mb/s Migration to Higher-Speed I/O
Voltage 1,5V 1,2V Reduced Memory Power Demand
Low Voltage Standard Yes (DDR3L at 1.35V) Anticipated at 1.05V Memory Power Reductions
Internal Banks 8 16 More Banks
Bank Groups (BG) 0 4 Faster Burst Accesses
VREF inputs 2 – DQs and CMD/ADDR 1 – CMD/ADDR VREFDQ Now Internal
tCK – DLL Enabled 300MHz – 800MHz 667MHz – 1,6GHz Higher Data Rates
tCK – DLL Disabled 10MHz – 125MHz (optional) Undefined to 125MHz DLL-off now fully supported
Read Latency AL + CL AL + CL Expanded Values
Write Latency AL + CWL AL + CWL Expanded Values
DQ Driver (ALT) 40 Ω 48 Ω Optimal for PtP Applications
DQ Bus SSTL15 POD12 Less I/O Noise and Power
RTT Values (in Ω) 120, 60, 40, 30, 20 240, 120, 80, 60, 48, 40, 34 Support for Higher Data Rates
RTT Not Allowed READ Bursts Disables during Read Bursts Ease-of-Use
ODT Modes Nominal, Dynamic Nominal, Dynamic, Park Add’l Control Mode; OTF Value Change
ODT Control ODT Signaling Required ODT Signaling NOT Required Ease of ODT Control; Allows Non-ODT Routing, PtP Apps
Multi-Purpose Register Four Registers – 1 Defined, 3 RFU Four Registers – 3 Defined, 1 RFU Provides Additional Specialty Readout
DIMM Pins 240 (R, LR, U); 204 (SODIMM) 288 (R, LR, U); 260 (SODIMM)
RAS ECC CRC, Parity, Addressability, GDM More RAS features; improved data integrity
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