How to create a good Audio clock? Use BB's Clock Generator
PLL1700!
But be warned, for the Oscillator you can use a "simple and
cheap 27MHz crystal". This is the original description in the datasheet.
But where is the problem? You have to use a fundamental crystal.
Looking at the catalog distributors, you would find (most) nothing
about the Mode for the crystal.
Trying some crystal and you will find, that you get overtone crystals
(3rd overtone).
If this type of crystal is not explicitly driven near the overtone
frequency, e.g. with a series or parallel resonant network (LC), it
will oscillate only at the fundamental ( about 9MHz is the fundamental
for an 27MHz 3rd overtone crystal):
The 27MHz frequency is the border between fundamental and overtone
Mode. Most crystal manufaturs produces fundamental crystals up to 24/25
MHz only.
The simplest solution to get the desired Audio frequencys out of
the PLL1700 is to use a 18.000MHz fundamental crystal.
The table below shows the frerquencys you would get now:
This seems to be the simpelst solution if you can't get a 27MHz
fundamental crystal.
If you want to know more about crystals, then go to the
manufacturs pages, they most have good application notes !
