Choosing a crystal.

Thread Starter

Gibson486

Joined Jul 20, 2012
355
I am trying to pick a crystal for an ARM processor.

Originally, I was going to use this:

http://www.abracon.com/Resonators/abls.pdf

but I ran out of space. As a result, I am thinking of using this:

http://www.txccrystal.com/images/pdf/7a.pdf

I am sort of confused, because I am not sure what I lose from going to one to another. I noticed that the first one listed Microprocessors as an application, but I am guessing that is for marketing and the other one will work as well? Also, I am assuming that the ARM cannot drive over 200 uW spec on the 2nd crystal. I am hoping that it really does not matter just as long as I get the caps to go with it correctly.
 

joeyd999

Joined Jun 6, 2011
5,234
I am trying to pick a crystal for an ARM processor.

Originally, I was going to use this:

http://www.abracon.com/Resonators/abls.pdf

but I ran out of space. As a result, I am thinking of using this:

http://www.txccrystal.com/images/pdf/7a.pdf

I am sort of confused, because I am not sure what I lose from going to one to another. I noticed that the first one listed Microprocessors as an application, but I am guessing that is for marketing and the other one will work as well? Also, I am assuming that the ARM cannot drive over 200 uW spec on the 2nd crystal. I am hoping that it really does not matter just as long as I get the caps to go with it correctly.
Underdriving a crystal is rarely a problem. Overdriving fractures the crystal. The second choice should work fine.

Crystal circuits on modern MCUs are easy today. Not like the old days. Just about anything works well.
 

dannyf

Joined Sep 13, 2015
2,197
Also, I am assuming that the ARM cannot drive over 200 uW spec on the 2nd crystal.
It is unlikely wise to assume. In general, you look for frequency, stability, packaging, price, etc.

I typically look for small load capacitance, 5 or 6pf ones are good in that the parasiticc capacitance would be sufficient.
 
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