[SI-LIST] Re: follow up: Re: Query about Oscillator problem

The terminology of "series" or "parallel" resonance when speaking of
quartz crystal resonators refers to the resonance mode where calibration
was established. 

Physically there is no difference between a series and parallel resonant
crystal. The type of resonance utilized in the oscillator has to do with
the oscillator topology. Some oscillators require the crystal to exhibit
a low impedance at resonance (the series mode), whereas other oscillator
types require a high impedance (parallel mode) to sustain oscillation.

Using a "parallel" resonant crystal in a "series" resonant oscillator
will result in a slightly different frequency of oscillation than the
crystal vendor intended, but it shouldn't materially affect the
oscillator functionality.

-Ray Anderson
Xilinx Inc.

> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx]
> On Behalf Of Richard Jungert
> Sent: Monday, February 01, 2010 1:49 PM
> To: steve weir; tlx6f@xxxxxxx; chundis@xxxxxxxxx; si list freelist
> Subject: [SI-LIST] Re: follow up: Re: Query about Oscillator problem
> 
> Guys
> 
> It may very well be that the series resonant quartz won't work and
that
> you may need to get a parallel resonant XTAL. Series resonant can get
you
> into trouble. I would go with the crystal type/mfg that Motorola
> recommends.
> 
> I would bet dollars to doughnuts that the resonant type is the issue
here.
> 
> Richard Jungert
> 
> 
> 
> 
> 
> > Date: Sun, 31 Jan 2010 15:20:46 -0800
> > From: weirsi@xxxxxxxxxx
> > To: tlx6f@xxxxxxx
> > CC: chundis@xxxxxxxxx; si-list@xxxxxxxxxxxxx
> > Subject: [SI-LIST] Re: follow up: Re: Query about Oscillator problem
> >
> > Li, that is not correct.  NPO capacitors are high stability and high
Q.
> > They are great for the crystal tuning caps where both
characteristics
> > are a plus.  But the high Q can actually create unwanted resonance
> > problems in the PLL power filter.
> >
> > Steve.
> > Li, Tianqi . (S&T-Student) wrote:
> > > Sree,
> > >
> > > I forget sth. You need to check the PLL filtering capacitors of
> MCF5212.
> > > In most cases CPU will leave out 2 or 3 power pins for filtering
PLL
> > > noise. Capacitors on these pins should also use NPO for a better
> > > performance.
> > >
> > > And you also need to find at what value of Vpp of XTAL droped to
the
> PLL
> > > start to lose locking. If the value is out of MCF5212 spec, the
root
> > > cause is surely on XTAL tank circuit; If not, it might be XTAL's
> glitch
> > > aroused. You can use scope to test the eye diagram and find the
> glitch.
> > >
> > > Tianqi Li
> > >

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