Spread spectrum usage

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Spread spectrum usage

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jhones
Contributor I

Hello,

I am trying to use spread spectrum for the i.MX7D by playing with STOP values according to reference manual formulas  but get unreasonable measurements in spectrum analyzer

What is the range that should be set in STOP value?

Thanks

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art
NXP Employee
NXP Employee

Since you use unreasonable STOP value, you see unreasonable result on the PLL output. In your case, the formally calculated spread spectrum range exceeds the PLL output frequency, that has no meaning. For normal operation, the spread spectrum range must be no more than some units of percents of target output frequency. So, try to use some more realistic STOP value that meets the formal calculation criteria.


Have a great day,
Artur

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