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Topic: Que:  Crystal issue (Read 800 times) previous topic - next topic

FireBALL

Hi,

I'm designing a custom arduino board based on arduino-pro.

I want to replace resonator with a crystal (digikey part number 535-9810-1-ND).  Basically i'm not sure about the load capacitor.  The component spec sheet says 10pf. so my question is do I need to use 10pf caps as load capacitors or it has to be some other value if yes than would be it be and what is the formula for calculating it?

thank you for the help and your time in advance.   :)

cheers

Grumpy_Mike

#1
Mar 17, 2010, 11:02 am Last Edit: Mar 17, 2010, 11:59 am by Grumpy_Mike Reason: 1
You won't need a capacitor with a resonator.

FireBALL

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You won't need a crystal with a resonator.

Why would I want to use them together???

I posted earlier that I want to replace resonator (the ceramic one) with a crystal (on it's own)  i hope it's clear now :)

Grumpy_Mike

Sorry I was thinking capacitor and wrote crystal. I spotted this and just corrected my post, then saw you picked up on it.
By and large you don't need to add any extra loading to get a resonator to run to frequency.

pwillard

When using a crystal.... I always refer to the CHIP datasheet for recommendations.  The ATMEL datasheet says 12-22pF.  I usually use 20pF with 16MHZ CPU crystals and have no issues. (I usually recycle crystals from old electronics and have good results with no specs available.)   That part, 535-9810-1-ND, should work fine but you might get best results with lower value (12-15pF) parts.

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