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What's the minimum refresh clock for SDRAM.

Discussion in 'Electronic Design' started by Boki, Oct 27, 2005.

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  1. Boki

    Boki Guest

    Hi All,
    What's the minimum refresh clock for SDRAM, I knew it depends on
    ram cell, but could you provide a reference? thank you very much.

    How about .25um process / 70ns speed.

    Best reagrds,
    Boki.
     
  2. Tim Wescott

    Tim Wescott Guest

    The best way to answer this would be to look at a data sheet. If you
    want a general answer look at a bunch of data sheets. If you want a
    theoretical answer then I can't help, but I suspect it would be "how
    long do you want?"
     
  3. Boki

    Boki Guest

    as low as possible, because it save power, isn't it ?

    Best regards,
    Boki.
     
  4. Spajky

    Spajky Guest

    in my first PC I had 66MHz PC66 sticks , Bios timings 60ns; I used
    the largest possible interval = 256us ... no crashes & faster
    performance ...
     
  5. Boki

    Boki Guest

    Why possible faster?
     
  6. Spajky

    Spajky Guest

    because when cells are read & refreshed with refreshing clock
    impulses, that time are not accessible for write/read operations for
    other stuff, thus less refreshing, better real life Ram performance;
    the differences can be up to few % ...
     
  7. Rich Grise

    Rich Grise Guest

    A longer interval means a less-often refresh cycle, stealing fewer cycles
    from the processor, albeit I find it a little hard to believe that the
    difference in performance would be _that_ noticeable. :)

    Cheers!
    Rich
     
  8. Boki

    Boki Guest

    lower refresh cycle doesn't mean lower processor load.

    I can't understand this yet.

    Best regards,
    Boki.
     
  9. mike

    mike Guest

    The minimum refresh rate is specified in the data sheet.
    If you do it less often, you build in intermittent loss of data.

    The only way to get reliability at lower refresh rates is to
    have the vendor select parts to YOUR custom specification.

    Quick step up to the soapbox...
    It's hard enough to make a reliable system if you adhere to all the
    component specifications. To do otherwise is folly.

    A more fruitful question might be, "Which vendors SPECIFY the longest
    refresh interval?"
    Soapbox off...
    mike

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  10. Pooh Bear

    Pooh Bear Guest

    It's not about processor load. You can't read / write memory when it's being
    refreshed.

    Also please don't top post Boki.

    Graham
     
  11. Pooh Bear

    Pooh Bear Guest

    Does it ? Hadn't heard that.

    Graham
     
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