Key Specifications
The table below shows the specifications comparison between DDR3 vs. DDR4:
Table 4. DDR3 vs DDR4
Feature/Option
DDR3
DDR4
DDR 4 Advantages
Chip Densities
512 Mb-8 Gb
4 Gb-16 Gb
Larger DIMM capacities
Data rates
800 Mb/s-2133 Mb/s
1600 Mb/s-3200 Mb/s
Migration to higher speed I/O
Voltage
1.5 V
1.2 V
Reduced memory power
demand
Low voltage standard
Yes (DDR3L at 1.35V)
Anticipated at 1.05V
Memory Power Reductions
Internal banks
8
16
Higher data rates
Bank groups (BG)
0
4
Faster burst accesses
VREF inputs
2 —DQs and CMD/ADDR
1 — CMD/ADDR
VREFDQ Now Internal
tCK — DLL Enabled
300 Mhz-800 Mhz
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&Omega
48&Omega
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 Types
RDIMM, LRDIMM, UDIMM,
SODIMM
RDIMM, LRDIMM, UDIMM,
SODIMM
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
DDR4 Details
There are subtle differences between DDR3 and DDR4 memory modules, as listed below.
Key notch difference
36
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