Lpc2000

At 01:12 AM 4/4/2006 +0000, unity0724 wrote:
>Some opinions needed:
>If I'm running CPU clock at 18MHz with an external 18MHz crystal,
>which is more reliable (over full temperature/voltage range):
>-  Switch off the PLL (clock source from external crystal/OSC)
>-  Turn on 1x PLL  (Clock source from PLL VCO/CCO)

The PLL almost certainly can't be more reliable than the oscillator since 
it uses the oscillator as an input. I'd just use the oscillator and leave 
the PLL off.  You do gain in having a simpler circuit and marginally 
simpler software but I doubt it makes a great deal of difference in 
reliability.  More noticeable would be a reduction in power requirements 
and perhaps EMI.

On the other hand unless there is a real difference in reliability why 
bother with the PLL

Robert

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