sram vs sdram

why use one rather then the other in a certain application

Same reasons as always. Cost vs. capacity vs. complexity vs. power consumption vs. speed vs. whatever. Choose what fits your requirements best.

Regards, -=Dave

capacity and cost aside. Speed you can get equivalent speeds

Those are the most important reasons in pretty much every design.

.. and temperature range. With static RAMs the power consumption is quite stable between -55 C .. +125 C, however, with dynamic RAMs the high refresh rate at higher temperatures will consume quite a lot of power, even if the memory is not accessed.

Paul

But speeds are not entirely equivalent, as with SDRAM you have addressing and refresh overheads, so speed for accessing completely random addresses is very much slower than the burst rate for consecutive data within a row.

awsome. thanks for the responses.

why is there such a difference in capacity between the two?

Because the 's' (pun intended) in SRAM is different from the 's' in SDRAM! SRAM stands for Static RAM, a kind of memory cell using flip-flops and memory contents can be retained indefinitely as long as DC power is present. SDRAM stands for Synchronous Dynamic RAM, a kind of memory cell using capacitors and cells have to be refreshed regularly to retain their contents. There are a few transistors in a flip-flop, so a flip-flop occupies a lot more space than a capacitor on an IC. One can pack several giga bits on a DRAM chip, but only several tens of mega bits of SRAM, as L1/L2/L3 cache memory on nowadays CPU.

My 2 cents.

Stephen W> awsome. thanks for the responses.