Hot DRAM

You should be ashamed of yourself! :-)

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!

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I'm never going to grow up.

No. Diode leakage will destroy the information stored on diode capacitors on each memory cell. The refresh happens too slowly.

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

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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

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Syd

can

a

What do you use to solder them? Some solder starts to melt at 180C.

That's OK, you can make up for it by posting a Thompson/Larkin flame.

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

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

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Syd

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

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Failure does not prove something is impossible, failure simply
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nico@nctdevpuntnl (punt=.)
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We had a TI computer with bubble memory one place I worked. It died every couple months, and TI had to send someone to repair or replace it.

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You can't have a sense of humor, if you have no sense.

And I thought he misspelled Damn.