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Using a spread spectrum oscillator with the PLL on the MCF52259

Question asked by RICK BOURGEOIS on Aug 25, 2014
Latest reply on Aug 27, 2014 by TomE

I am using MCF52259 in several projects and every time I bring the project to the emissions lab for FCC testing I get sneered at for 1) Not using multilayer PCB and 2) not using a spread spectrum oscillator.

The multi-layer PCB is a management issue and cannot be resolved.

The use of a spread spectrum oscillator is my only hope for a design that will have multiple frequencies and oscillators..

The SSO will change the frequency slightly (1 - 2.5%) over time so that a peak frequency will not stand out and thus pass emissions.

If I am using the PLL to increase the frequency (I require 80MHZ) will it not average out the oscillator frequency and ruin the effect of the SSO?

Has anyone out there used an oscillator?

What is the highest frequency I can use for my external oscillator?

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