What size cap for 6 Mhz xtals?

Chris_D

Hi

What size caps shoudl I use to load the crystal on the propeller?· This is for a 5 Mhz xtal.

I don't see any on the prop demo board but use them on the AVR's xtals I also work with.

Thanks

Chris

Carl Hayes

That will be specified by the crystal manufacturer. or by you if you're ordering custom crystals. A typical value would be about 18 pf.

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· -- Carl, nn5i@arrl.net

photomankc

I thought the Propeller had selectable internal load capacitors?

Phil Pilgrim (PhiPi)

You don't use external caps with the Prop. You need to select a parallel-resonant crystal rated for the Prop's load capacitance at the appropriate drive level. For 5 & 6MHz, this would be about 18pF.

-Phil

Whit

Chris_D,

See this page - http://mikronauts.com/products/mikronauts-625mhz-crystal/

Toward the bottom of the page is some Q and A that might be helpful. Is this what you where wondering about?

If not, What·are these caps for?

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Whit+


"We keep moving forward, opening new doors, and doing new things, because we're curious and curiosity keeps leading us down new paths." - Walt Disney

Post Edited (Whit) : 9/2/2009 7:20:11 PM GMT

Chris_D

Arghhh - fat fingers.· I meant 5 Mhz not 6 Mhz!

As I purchase my xtals from Parallax when I order chips, I would assume they would be of the correct type for this application.· I guess I better check into it a bit more just to be safe.

Thanks guys,



Chris

AJM

Chris,

Your assumption is correct:

www.parallax.com/Store/Components/ResonatorsCrystals/tabid/153/CategoryID/18/List/0/SortField/0/Level/a/ProductID/341/Default.aspx