[SI-LIST] : Crystal Question

Goodarz Goodarzi (ggoodarzi@acacianet.com)
Tue, 07 Apr 1998 12:13:24 -0400

Hello,
This is my first time asking a question on this forum, so please bear with me.
I am looking at a clock generator, which has its own internal ref
oscillator.
This device requires an external crystal. The manufacturer requires the
crystal to be a parallel resonant crystal and that its load capacitance
must match the load capacitance of the internal oscillator circuitry of the
clock generator. The load capacitance of the internal oscillator circuitry
is 18 pf. The spec for the 20 MHz crystal that I intend to use however is
vague and only gives a range form 10 to infinity pf. My questions are:

1) What is exactly meant by parallel resonant crystal. Does it mean how
you connect it to the clock generator chip or is it specific to how the
crystal is cut?

2) How can I fould the exact load capacitance of a crystal?

Thank You
Goodarz Goodarzi