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QUARTZ CRYSTAL OSCILLATOR
A timing device that consists of a crystal and an oscillator circuit,
providing an output waveform at a specified reference frequency.
CENTER FREQUENCY
The specified reference frequency of the oscillator, typically specified
in megahertz (MHz) or kilohertz (kHz).
FREQUENCY TOLERANCE/STABILITY
This "inclusive" specification is the amount of frequency deviation
from the center frequency associated with a set of operating
conditions. These conditions include: Operating Temperature Range,
Supply Voltage, and Output Load. This parameter is specified with a
maximum and minimum frequency deviation, expressed in percent
(%) or parts per million (ppm).
LOGIC LEVELS
Defined as the Output Voltage Logic High or "Logic 1" and the Output
Voltage Logic Low or "Logic 0" (Figure 1).
DUTY CYCLE
The measure of output waveform uniformity. This term, also referred
to as symmetry, is a measurement of the time that the output
waveform is in a logic high state, expressed as a percentage (%).
This parameter is measured at a specified voltage threshold or at a
percentage of the output waveform amplitude (Figure 1).
RISE/FALL TIME
The Rise Time, measured in nanoseconds (nSec), is defined as the
transition time from an output logic low to an output logic high.
Conversely, the Fall Time, also measured in nanoseconds (nSec),
is defined as the transition time from an output logic high to
an output logic low. This transition time is measured at specified
voltage thresholds or at specified percentages of the output waveform
amplitude (Figure 1).
START-UP TIME
The specified time from oscillator power-up to the time the oscillator
reaches steady state oscillation.
LOAD DRIVE CAPABILITY
The maximum load the oscillator can drive specified in terms of the
number of gates or the type of load circuit (Figures 2,3,and 4).
SUPPLY VOLTAGE
The DC input voltage necessary for oscillator operation, specified in
volts.
INPUT CURRENT
The amount of current consumption by an oscillator from the power
supply, typically specified in milliamps (mA).
TRI-STATE OUTPUT
An oscillator with this feature allows the output to be placed into a
high impedance state. This feature is activated by the application of a
logic control voltage to pin 1 of the oscillator.
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