Author Topic: Atmel XMega CPU @ 32MHz -> PLL or RC oscillator?  (Read 426 times)

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Offline bernroth

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Atmel XMega CPU @ 32MHz -> PLL or RC oscillator?
« on: December 04, 2017, 05:14:27 pm »
Hello folks!

Atmel XMega controllers have internally a 32MHz RC oscillator and a PLL.

If the CPU shall only run @ 32MHz, would you choose RC or PLL?
PLL clock source is internal (RC) as well.

Is there a good reason to actually use the PLL?

From my point of view there is none.
I can switch it off and save some power.

Is there maybe something I have overseen?

Is the PLL more stable when it comes to external noise?
Temperature stability should make no difference at all as it would affect the 32 MHz RC as well as the RC ocsillator for PLL.

Background: I am doing some firmware for a finished product which does (unfortunately) not have an external crystal for the PLL. This would be my preferred choice.

The firmware works well with 32MHz RC as well as with 32MHz PLL.

Any feedback welcome, thanks!
Best regards,


« Last Edit: December 04, 2017, 10:10:56 pm by bernroth »

Offline krho

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Re: Atmel XMega CPU @ 32MHz -> PLL or RC oscillator?
« Reply #1 on: December 05, 2017, 04:58:40 pm »
afair when you run it with pll you can synchronize everything against internal 32kHz RC and have very precise clock

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