Atmega32u4 Breakout Crystal Question

For Adafruit customers who seek help with microcontrollers

Moderators: adafruit_support_bill, adafruit

Please be positive and constructive with your questions and comments.
Locked
User avatar
mobilewill
 
Posts: 49
Joined: Mon Dec 13, 2010 7:58 pm

Atmega32u4 Breakout Crystal Question

Post by mobilewill »

I am working on a project with an embedded 32u4 and was using the Adafruit 32u4 breakout as an example. I was wonder about the crystal load capacitors. The schematic has 2 18pf capacitors and the only crystals on digi-key that are the same need 8pf. I know you have to account for other stray and pin capacitances but I wanted to make sure this was right. Also was wondering which part was used if it was the one with 30\20ppm tolerance for 50\50.


Thanks

User avatar
easternstargeek
 
Posts: 347
Joined: Mon Dec 13, 2010 1:39 pm

Re: Atmega32u4 Breakout Crystal Question

Post by easternstargeek »

I've never put a great deal of thought into selecting crystal loading capacitors, and that has never caused me difficulty.
For the most part, that your crystal will be quite forgiving of the things you mention. Put another way, ordinary ceramic caps are most commonly used, and they're not known for being the "best of the best" as performance goes.

Locked
Please be positive and constructive with your questions and comments.

Return to “Microcontrollers”