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DDR SDRAM

DDR SDRAM is Double Data Rate SDRAM.

DDR SDRAM is an improvement over regular SDRAM, also known as SDR SDRAM (Single Data Rate SDRAM).

DDR SDRAM doubles the Glossary Link bandwidth of SDR DRAM by transferring data twice per cycle on both edges of the clock signal, implementing burst mode data transfer.

DDR SDRAM is being supplanted by DDR2 SDRAM.

Standard DDR SDRAM DIMM's

DDR SDRAM is normally packaged in DIMM modules.

DIMM Module Chip Type Clock Speed Data Rate Transfer Rate
PC1600 DDR200 100 200 1,600
PC2100 DDR266 133 266 2,133
PC2400 DDR300 150 300 2,400
PC2700 DDR333 166 333 2,667
PC3000 DDR366 183 366 2,933
PC3200 DDR400 200 400 3,200
PC3500 DDR433 216 433 3,466
PC3700 DDR466 233 466 3,733
PC4000 DDR500 250 500 4,000
PC4300 DDR533 266 533 4,266

Standards for DDR SDRAM

DDR SDRAM standards are still being developed and improved.

DDR SDRAM Standard Frequency (MHz) Voltage
DDR 400-533 2.5
DDR2 667-800 1.8
DDR3 1066 to ... 1.5

Higher frequencies enable higher rates of data transfer.

Lower voltages result in less heat radiation and longer batter life for portable computing devices. They also allow greater component density, which allows higher capacity in the same package size.

Discuss DDR SDRAM in the forums.