Re: Fastest TWGS and ZIP GS

[gregt@porsche.visix.com (Greg Thompson)]

>"Frank" == Frank M Lin <fmlin@netcom.com> writes:

>> From which speed have I to higher the 5V Vcc Voltage ? I can also
>> rember that the WDM samples have printout of MHz/Vcc ...

  Frank> Don't you guys ever read the faq?  :) The chart is called the
  Frank> shmoo plot.  Each high-speed '816 includes one.

>    Why do you need to increase the voltage to make a chip go faster?
>Why isn't it enough to simply pump up the speed of the crystal?  I know,
>simply question, complex answer... :)

  Frank> Well, I think the crystal is more like a speed regulator, and
  Frank> the voltage is like octane booster.  :)

  Yeah, pretty much.  The crystal sets the clock for the chip
(obviously).  If the logic in the chip can't switch fast enough to
meet various timing requirments (setup & hold time and such), then the
chip won't be performing its job.  One way to make the chip's internal
logic run faster (decrease the switching time) is to up the voltage.
This is dangerous, though, 'cause it screws with the logic levels, as
well as making the chip run hotter, possibly leading to fatal
problems.  So tweaking the voltage up a little bit will make the chip
switch faster, but not actually run faster.  That's probably kinda
confusing, but then again, what isn't?

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