What does Burst Length in DDR SDRAM......

[rakesh_aadhimoolam]

ddr burst length

what does the Burst length in DDR SDRAM refer to......

DDR1 has a Burst length of 2
DDR2 has a Burst length of 4
DDR3 has a Burst length of 8

Thanks.....

 

[satyakumar]

dram burst length

Hi,
It indicates how many data bytes are writern are read from DDR sdram when write or read command is given along with row and coloumn address.

 

[sree205]

ddr burst

Assuming we have a data bus width of 4 bytes, i think burst length means, how many 4 bytes are written or read.

so, for a burst length of 4, we have 4x4 = 16 bytes of information.

 

[seenu]

sdram burst length

Burst length referes to the amount of data read/written after a read/write command is presented to the DDR/SDRAM/QSDRAM.....controller.

This effectively reduces the latency for r/w operations

Differenciating to the older DRAM's,
Suppose we need to 8 words from memory
In normal dram after a read command is given the data fetch time is say 1ns, so it will take 8ns and 8 read commands for complete operation

But for a SDRAM, the first command will take 1 ns and further reads dont need a read command since its mentioned as burst of 8 it will read the remaining 7 words in say each at .5ns and finally we have 8 data at 4.5ns with only one read operation

So burst operation reduces latency when accesing consecutive memory locations
others a burst size of 1 is like normal r/w operation