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Issue
91, February 1998
Choosing the Right
Crystal For Your Oscillator
by
Norman Bujanos
Although
critical to the timing of your design, crystals are glossed
over in engineering schools. Norman puts a stop to that.
His review of crystal parameters gets you up to snuff when
it comes to picking the right crystal for your design.
Start
•Why Quartz Crystals
• Timing Budget &
Accuracy
• Frequency
Tolerance
• Frequency
Stability
• Aging • Load
Capacitance •
Series and Parallel Resonance •
Frequenct Tolerance and Load Capacitance
• AT vs. BT Cut
• Mode of Operation
•
Package Considerations •
Crystal Placement •
Crystal Clear • References
Selecting quartz crystals
for oscillators can be confusing and mysterious. Engineering
programs tend to give them only a cursory overview.
Hence, many engineers are
unfamiliar with crystal parameters and jargon. A crystal
datasheet can appear to be as cryptic as Egyptian hieroglyphics.
In this article, I cover
crystal parameters and explain how system design can affect
clock accuracy. It should make crystal selection significantly
easier.
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