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crystal, EMI and capacitor

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weeb0

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Hello,

I plan to use the mcp2515 ( can bus driver ) and I have to select an osc for it.

I have to use a crystal that have a frequency of over 40MHz. At that frequency, I'm scared about the EMI that I can cause.

What can I do to minimize EMI?
How to select the decoupling cap? ( is it the crystal load capacitance? )

The crystal I would like to use : https://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=CTX656CT-ND

thank you a lot for your help
 

obinobi

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Hello

Did you want to use 40 MHz for some external bus clocking?

If yes you may add a RC on a clock net (but not on a oscilator) circuit to increase fall and rise time of clock signal. It will decrease higher harmonics of the clock signal.

Best regards
 

weeb0

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Hello,

Thank you for your reply.

The crystal will be used only to clock 1 component. He will be placed very near of the component.

Thank you
 

obinobi

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Hello
So you may implement shielding of clock net and oscillator. I mean ground plane under and copper plane nearby the crysta connected together through viasl. It's should be enough.

Best regards
 

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