Crystal oscillators can be manufactured for oscillation over a wide range of frequencies, from a few kilohertz up to several hundred
megahertz
The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or Cycle per second, cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, me ...
. Many applications call for a crystal oscillator frequency conveniently related to some other desired frequency, so hundreds of standard crystal frequencies are made in large quantities and stocked by electronics distributors. Using
frequency dividers,
frequency multipliers and
phase locked loop circuits, it is practical to derive a wide range of frequencies from one reference frequency.
The
UART column shows the highest common
baud rate (under 1,000,000), assuming a clock pre-divider of 16 is resolved to an exact integer baud rate. Though some UART variations have fractional dividers, those concepts are ignored to simplify this table.
References
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Electronic oscillators
Electrical components