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DDR to DDR2

DDR2 - Why Consider It?

Compared to DDR, DDR2 offers extraordinary performance, reduces power consumption, maximizes DRAM throughput, improves signal integrity, and optimizes flexibility. Some of the measurable differences are highlighted in the comparison chart below.

Feature/Option DDR DDR2 DDR2 Advantage
Package 66-pin TSOP
54-, 60-ball FBGA
60-, 84-ball FBGA
63-ball FBGA DDP
Enables better electrical performance and speed, dual die package enables higher densities
Voltage (core and I/O)

Low volt
2.5V-2.6V

N/A
1.8V

1.55V
Reduces memory system power demand

DDR2 offers a low voltage solution
Densities 256Mb to 1Gb 256Mb to 4Gb High-density components enable large memory subsystems with fewer chip counts
Internal banks 4 4 and 8 1Gb and higher density DDR2 devices have 8 banks for better performance
Prefetch (MIN WRITE burst) 2 4 Enables faster clock rates
Data rate (MT/s per pin) 333
400
667
800
533
667
800
1066
Migration to higher data bandwidth
READ latency

Additive latency (posted CAS)
2, 2.5, 3 CLK

N/A
CL + AL
CL=3, 4, 5, 6, 7

AL options
0, 1, 2, 3, 4, 5, 6
Eliminating one-half clock settings helps speed internal DRAM logic and simplify timing

Mainly used in server applications to improve command bus efficiency
WRITE latency 1 clock READ latency - 1 Improves command bus efficiency
DQ bus termination Motherboard parallel to Vtt DRAM on-die termination (ODT), optional on-motherboard termination ODT for both memory and controller improves signaling, lowers power, and reduces system costs
Data strobes Single-ended Differential or single-ended Improves system timing margin by reducing strobe crosstalk
Modules 184-pin DIMM
  • unbuffered
  • registered
200-pin SODIMM
240-pin SODIMM
  • unbuffered
  • registered
  • fully buffered
200-pin SODIMM
Improved layout, more form factors, and power delivery design