> >2. Packaged resonators are much smaller than crystals .
>=20
> This is quite interesting, I actually thought HC49 SMD takes less space
> than Ceramic resonator or they should be very close on PCB real estate.
> Am I wrong?
>=20
> >3. Cost is less than 1/2 that of crystals, and comes with the two=20
> phase-shift caps built-in.
>=20
> Any part number on Mouser or digikey? The HC49 SMD crystal I am using is
> around 30 Cents in 1K quantity. Actually some ceramic resonator I have
> checked with 0.x% accuracy performance either cost more or cost about
> the same.

I'm a resonator type person, most recently I've used the Murata
CSTCE8M00G55Z in small quantities from Farnell (Element14) and also listed
by Digi-Key & Mouser. These ones are a nice small physical size (close to
0805 size but longer), anything bigger looks out of place next a QFN
packaged micro. No doubt you can find something cheaper... but for me
Murata is a trustworthy name and I've had good experience with their
resonators coupled to PIC micros. In this application they are in a high
vibration environment (brush chipper/tree shredder) and I haven't had any
failures yet, touch wood :-P

I did try using the internal RC oscillator once for serial comms between
two PIC16F886's. Datasheet spec of 1% (IIRC) seemed good enough, and it
almost was. I had devices operating at different temperatures, and some
pairs wouldn't talk to each other. I could have persisted and tried auto
baud rate detection or other tricks, but in the end I switched to a 3
terminal resonator and the problem just went away.
--=20
Brent Brown, Electronic Design Solutions
16 English Street, St Andrews,
Hamilton 3200, New Zealand
Ph: +64 7 849 0069
Fax: +64 7 849 0071
Cell: +64 27 433 4069
eMail:  brent.brown@clear.net.nz


--=20
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