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From: "Michael A. Terrell"
Subject: Re: Querry, Kick Starting Crystal Oscilator.
Date: Sat, 09 Nov 2002 00:17:37 -0500
Organization: Have you seen my bench? No, really! Where is it?
X-Mailer: Mozilla 4.61 [en]C-CCK-MCD (Win95; U)
Roy McCammon wrote:
> I've got a processor with a 32KHz crystal. The problem
> is that the crystal oscillator can take a l_o_n_g time
> to start and stabilize.
> My though is to build a 32KHz cmos schmidt trigger RC
> oscillator and feed that through a small capacitance into
> the input of the crystal oscillator to get it going.
> Any thoughts?
> Thank you for reading and or replying
> If you are one in a million, there are 6000 people just like
> Local optimization almost never yields global optimization.
> Opinions expressed herein are my own and may not represent those of my employer.
have you tried a different brand of crystal? Some are definitely
better than others. I worked with the Motorola MC68340 series processor
for four years.
http://e-www.motorola.com/brdata/PDFDB/docs/MC68340UM.pdf page 389 shows
some variation in two different crystals they used. We used slightly
different capacitors, and the series resistor was lower in value, but
they started quickly, and reliably. I can't give more information due
to the NDA I signed, but this might help.
I believe this was the crystal we used
http://www.ecsxtal.com/pdf/ecs-3x8.pdf from ECS crystals and was
Digi-Key stock number X801-ND. If you search Digi-Key for 32.768 KHz
crystal you will see they carry quite a wide range in specifications.
Michael A. Terrell
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