Resonators

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1

I’m building a PCB that uses a 3-pin resonator for the system clock, but
farnell dont seem to have any UK stock of the right spec (16MHz 22pf).

Am i right in thinking a resonator is equivalent to a crystal and two
capacitors? So i can put a low profile 16mhz crystal in the outer pins and
add a couple of 22pf capacitors to the middle pin?

Ta,
Bob

2

I’m building a PCB that uses a 3-pin resonator for the system clock, but
farnell dont seem to have any UK stock of the right spec (16MHz 22pf).

Am i right in thinking a resonator is equivalent to a crystal and two
capacitors? So i can put a low profile 16mhz crystal in the outer pins and
add a couple of 22pf capacitors to the middle pin?

Yes, as far as I know. In fact the new Uno boards use a resonator
instead of a crystal, presumably because it saves 0.00001p per unit or
something - yet another reason to avoid them, methinks.

http://www.ladyada.net/library/arduino/unofaq.html

Alan Burlison

3

I hate combined resonators. They drift in frequency with changes of
temperature badly…Never seem to oscillate properly at the correct
frequency and use inferior capacitors. I have also found that
depending on layout they can be affected by EMI.

I would much prefer to use a separate crystal and decent C0G or NP0
capacitors…however you will pay slightly more for the extra
components. It all depends on how and where the designer is prepared
to compromise.

AlexOn 2 May 2012 10:20, Alan Burlison alan.burlison@gmail.com wrote:

On 02/05/2012 09:16, Bob Clough wrote:

I’m building a PCB that uses a 3-pin resonator for the system clock, but
farnell dont seem to have any UK stock of the right spec (16MHz 22pf).

Am i right in thinking a resonator is equivalent to a crystal and two
capacitors? So i can put a low profile 16mhz crystal in the outer pins
and
add a couple of 22pf capacitors to the middle pin?

Yes, as far as I know. In fact the new Uno boards use a resonator instead
of a crystal, presumably because it saves 0.00001p per unit or something -
yet another reason to avoid them, methinks.

http://www.ladyada.net/library/arduino/unofaq.html

–
Alan Burlison

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