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Hot DRAM

Discussion in 'Electronic Design' started by Syd Rumpo, Sep 20, 2011.

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  1. Syd Rumpo

    Syd Rumpo Guest

    Apologies for the non-political post.

    Does anyone know if DRAM will work at high temperatures, say above
    150'C, hopefully 180'C (300F - 360F)? I know it's out of spec, and can
    accept a reduced lifetime and speed, but will it work?

    Cheers
     
  2. PeterD

    PeterD Guest

    I do a fair amount of work with 'hot' components (automotive engine
    management modules), and personally I don't think this will fly. We find
    that longer term exposure to 100C will cause failures in as little as a
    few months, and you're talking 50 to 70% higher.

    I suppose if this is a testing environment, just to see if it might
    work, you may be successful.

    Oh, and I've not tried DRAM at high temps, so the above comment may well
    be worthless to you!
     
  3. If you scale the typical 64msec refresh by a doubling every 10°C to
    180°C you get a refresh every 88usec, or a row every ~10nsec. Maybe if
    you spent half the time doing refreshes, ran a little cooler and did a
    lot of testing you might get close.

    I don't think I've seen DRAM offered by the guys who sell the high
    temperature qualified parts, just SRAM.

    Ordinary parts also typically have high current densities in wee
    narrow conductors so they can die by electromigration in a matter of
    months at ~200°C.


    Best regards,
    Spehro Pefhany
     
  4. Syd Rumpo

    Syd Rumpo Guest

    Thanks all for your opinions.

    Yes, I was thinking to up the refresh rate and doubling every 10'C is in
    line with Arrhenius. As for months, that would be ok, it's only 180'C
    for hours or days at a time. It looks like I might have to test some -
    my feeling is that the sense amplifiers will be the issue.

    The very high temp SRAMs are amusing - Digikey has the HT6256 32KiB
    225'C part for USD 537.50 each. That's three hundred and forty quid - a
    penny a byte.

    Cheers
     
  5. Rich Grise

    Rich Grise Guest

    At first, I wondered, "A hot dram of what?" ;-)

    I wonder if the surplus shops have all sent their core planes to the
    landfill? ;-) Wouldn't a core memory work almost up to the Curie point
    of the ferrite?

    And whatever happened to magnetic bubbles?

    Thanks,
    Rich
     
  6. Syd Rumpo

    Syd Rumpo Guest

    On 20/09/2011 21:30, Rich Grise wrote:

    Hot whiskey - an equal measure of whiskey and boiling water with a few
    cloves, a squeeze of fresh lemon juice and a dollop of honey. Good for
    cold days.

    Core would be even more than a penny a byte, so a few megs would be
    beyond my means and probably bigger than a big thing during
    international big-things week.

    As for bubbles, I remember going to a seminar on those. IIRC they were
    256KiB devices and quite large - a good idea but too late, too expensive
    and soon overtaken.

    Cheers
     
  7. Nico Coesel

    Nico Coesel Guest

    Well, refresh faster! DDR2 memory typically has a normal temperature
    and high temperature self-refresh mode.
     
  8. John S

    John S Guest

    And I thought he misspelled Damn.
     
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