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Politics : Formerly About Advanced Micro Devices -- Ignore unavailable to you. Want to Upgrade?

To: Yousef who wrote (26500)	12/7/1997 2:58:00 AM
From: Petz	Read Replies (1) \| Respond to of 1574028

Yousef: re:<As long as the junction temperature stays within specifications, there will be no problem> This statement is not at all true. The GPS satelite system must operate for 7.5 years or my company loses on the order of $20K per day that it doesn't. Since the microprocessor in this payload is operating as high as 90 degC junction temperature (if I remember correctly), it is one of the limiting factors in life expencancy for the overall payload and, in fact, we need to have a redundant CPU in the system to keep P(failure) low. (the cpu takes 10w, but fans don't work very well in a vacuum!) The difference between changing temperature and voltage is ... junction temperature can be controlled with "heatsink" design, increased Electric fields due to increased voltages cannot be as easily compensated. This is very true. Without knowing the details of oxide thickness and transistor geometry, it is impossible to determine at what voltage electric fields become a factor. I can only accept the statement in the specification for the AMD-K6 MMX Enhanced Processor quoted in techstocks.com This discussion reminds me of a story from my childhood that may warm the hearts of the over-45 crowd on this thread. My father had bought a spanking new Heathkit Stereo Receiver, think it was called the AR-15, this was about 1965 plus or minus a year, and I was in 9th grade (no, bought it assembled, not as a kit). This receiver was years ahead of most stereo components (>100w RMS output, 70db FM alternate channel selectivity, etc -- way beyond any integrated components of that era). However, after 3-4 months one channel of the tape recording output failed. The unit was returned an fixed with no charge and the invoice indicated that they had replaced a transistor. (a 2N3903?) Several months later, the tape output in the other channel became noisy (hiss). Now, I looked at the schematic and saw that the transistor at the tape output was used in an emitter follower configuration (to give low output impedance). I also noticed that the supply voltage there was 27v, but the RCA transistor manual said the transistor was only rated 25v max Vce. We called Heathkit, complained about the noisy transistor and followed up with a letter. Despite the fact that the unit was now out of warranty, they appologized profusely and replaced both transistors with higher voltage models. My brother in NJ still uses this receiver, its doing fine. I don't know what this story has to do with AMD, but thought there might be a few old-timers that remember the days of no IC's, basic transistor circuit design and things like Heathkit products (intercoms, audio, ham radio etc.). Petz