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From: terry@cs.weber.edu (A Wizard of Earth C)
Subject: Re: Question on Diamond Clock Synthesizer
Message-ID: <1992Oct19.190736.11988@fcom.cc.utah.edu>
Sender: news@fcom.cc.utah.edu
Organization: Weber State University (Ogden, UT)
References: <1b7tmgINNi06@agate.berkeley.edu> <1992Oct19.082420.16353@Informatik.TU-Muenchen.DE> <1992Oct19.151409.24581@osf.org>
Date: Mon, 19 Oct 92 19:07:36 GMT
Lines: 82
In article <1992Oct19.151409.24581@osf.org> kenny@osf.org (Kenneth Crudup) writes:
>In article <1992Oct19.082420.16353@Informatik.TU-Muenchen.DE>
>roell@informatik.tu-muenchen.de (Thomas Roell) writes:
>
>>There are a few limitations like the highest frequency the chip can produce
>>(without emitting that neat smoke)
>
>Yeah, like maybe CLK/1????
>
>...
>
>>So what would happen if you programm the PLL wrong and blow your board ?
>
>ONCE MORE- explain to me exactly how programming a divider value into a
>chip WILL BLOW IT!!!
>
>If you run some chips (the i486 comes to mind) at higher speeds, they will
>dissipate more power, and could (BIG emphasis on could) overheat to the
>point where the chip becomes unreliable, but NOT fail. No chips on my
>SS24x run anywhere near warm, and definately less than the heat generated
>by my AMI 386-40. In order to get any type of useful divider resolution,
>the clock freq in has to be quite high. If you "program the PLL wrong"
>so that you generate one of these "chip-blowing high frequencies" YOUR
>MONITOR WILL SHOW IT (or I guess you'll tell me, despite my kicking holes
>in that theory, that it will blow your monitor too?)
>
>Either give me a full technical explanation, or quit talking shit! How much
>*is* Diamond paying you?
1) It is unlikely that Thomas is being paid by Diamond to basically
bad-mouth their products. His is an acceptable tactic, given that
slander is defined to involve misrepresentation, and to my knowledge,
Thomas has yet to misrepresent a Diamond product. I can call Hitler
genocidal, and that would be bad-mouthing him, but few people would
regard it as slanderous (to bring up the whole "Hitler thing" of
two months ago).
2) Whether an overheated chip becomes permananetly unreliable or only
temporarily unreliable is beside the point. Can you accurately
predict how much current the chip can sink when it is unreliable?
How about when the heat raises the resistance in the pull down/up
resistors causing yet more current to be sinked?
3) Intel's television adds have led us to believe that a chip works
best when it's glowing cherry red; would you have us believe the
same? 8-).
4) PLL's sink more current at higher frequencies. What is the frequency
limit before too much current is sinked? Could it be that multiple
chips being tied to the same output burn the current *source*? Thus
while the chip doing the malfing is left intact, the board is still
rendered useless.
I posit:
1) Thomas isn't a Diamond employee. 8-).
2) An overheated chip has unpredictable electrical characteristics, and
overheating can debond the casing or the attachment pads. Thus while
the chip isn't destroyed, microsuregery is required to make it operate
again.
3) Silicon/Boron semiconductors don't like heat. I have actually seen
a chip crack due to overheating (A UART on a DHV11).
4) Sinking too much current from a TTL chip in a monitor can fry the
chip or other components (I have seen the monitor portion of a
Televideo 912 kill multiple IN914 diodes as a result of sinking
too much current through them).
Terry Lambert
terry@icarus.weber.edu
terry_lambert@novell.com
---
Any opinions in this posting are my own and not those of my present
or previous employers.
--
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