At 11:51 PM 7/14/2005 +0200, you wrote:
> > Use a more tolerant crystal, a crystal with lower Rs, lower the
> > Vdd, add a series resistor, lower the load capacitor values.
> > All have side effects (the last three will prevent the oscillator from
> > starting if taken to extremes).
>
>I agree with the resonator, but for the applications that require the
>accuracy of a crystal, what would be the practical solution? Of the
>things you mention only the series resistor seems practical to me (the
>average tinkerer will more likely stock a suitable range of resistors
>than a suitable range of capacitors, and you can't lower the capacitors
>below the PCB and other stray capacitance). So what would be a practical
>value for a series resistor?

The general theme on determining the value is to increase the value
of the resistor until it no longer starts reliably, then reduce it, allowing
some safety margin for all the variations possible, and check that drive power
is well within ratings at that point. If it requires too high a drive power
to start reliably then you might have to change one or more of the other
factors.

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com




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