On Sun, Jan 07, 2007 at 11:52:57PM -0600, Seth Goodman wrote: > Douglas Tutty wrote on Sunday, January 07, 2007 4:20 PM -0600: > > > Most electronics are designed for an ambient (to them, not the case) > > temperature of 25 C max. > > It would be nice if we could assume that when designing hardware, but > it isn't realistic. Even for a benign laboratory environment, we > normally assume 40 degrees max ambient, which means the air and all > surfaces surrounding the case. Industrial electronics are often > designed for 50 degrees ambient with the case interior being 15 > degrees higher. > You mean that if you take a number off a chip and look it up in the manufacturer's datasheet it will say it will tolerate an ambient temp of 50C? I'm not necessarily thinking of a major heat source like a CPU/GPU or a power transistor but a simple TTL or CMOS support chip. What about the clock occilator? They __used__ to go haywire if you let them heat up too much.
I'm not saying that the support chips won't work at higher temps but it shortens the bathtub curve. Its one of those rules-of-thumb: if you can't leave your thumb on the chip comfortably, then its too hot. Mil-spec has a different rule of thumb of course. Then its not your thumb but a delegated thumb:-) Electronics designed from the outset for extreme environments will of course work in them. E.g. automobile stuff, Mars rover, pacemakers (water cooled at 38 C). The OP I think was talking about a regular consumer-grade computer so I limited my focus to that. How can a laboratory environment of 40 C be called benign? I conk out at 28 C. Doug. -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
