On Oct 23, 5:27 pm, "David Spencer" <davidmspen...@verizon.net> wrote:
> <MikeShepherd...@btinternet.com> wrote in message
>
> news:[email protected]..
>
>
>
> > Although it's not expressed in DRAM specs and you wouldn't want to
> > rely on it, the effect of reducing refresh rate is to increase the
> > access time. I'm not up-to-date with DRAM technology, but my
> > experience with devices 30 years ago was that you could turn off
> > refresh (and all other access) for 10s or more without losing the
> > contents, provided you weren't pushing the device to its access time
> > limits.
>
> > So, it's not impossible that reducing refresh rate would have a use
> > (albeit outside the published device spec). But, as you suggest, it
> > would help if he would just tell us what he's trying to do.
>
> > Mike
>
> Although that may well be the case for asynchronous DRAMs (because the
> reduced charge in the memory cell capacitor would mean that the sense
> amplifier took longer to register the state), this would not be the case for
> SDRAM since this registers the outputs a fixed number of clocks after the
> access starts. If the underlying access time increased by too much then the
> data would just be wrong.

For certain addressing patterns, the refresh can be eliminated
alltogether, when the addressing sequence is such that all (used)
memory cells are naturally being read, and thus refreshed, within the
required time.
Peter Alfke