Quartz Crystal Oscillator Glossary of Terms - Digi-Key

Nominal frequency: The center or nominal output frequency of a
crystal oscillator.
Package: Crystal oscillators are packaged in various styles from lead
through holes to surface-mount types. Various sizes and functions are
suitable for different applications.
Frequency tolerance: The deviation from the nominal frequency in
terms of parts per millions (ppm) at room temperature. (25° ± 5°C)
Frequency range: The frequency band that the oscillator type or
model can be offered.
Frequency stability: The maximum allowable frequency deviation
compared to the measured frequency at 25 °C over the temperature
window, i.e., 0° C to +70° C. Typical stability is ± 0.01% ( ±100 ppm).
Operating temperature: Temperature range within which output
frequency and other electrical, environmental characteristics meet the
Rise Time (Tr ): Waveform rise time from Low to High transition,
measured at the specified level
10% to 90% for HCMOS,
20% to 80% for ECL
0.4 V to 2.4V for TTL.
Fall Time (Tf ): The waveform fall time from High to Low transition,
measured at the specified level
90% to 10% for HCMOS,
80% to % for ECL
2.4V to 0.4V for TTL.
Jitter: The modulation in phase or frequency of oscillator output.
HCMOS / TTL Compatible: The oscillator is designed with ACMOS
logic with driving capability of TTL and HCMOS loads while
maintaining minimum logic HIGH of the HCMOS.
Aging: The relative frequency change over a certain period of time.
This rate of change of frequency is normally exponential in character.
Typically, aging is ± 5ppm over 1 year maximum.
Tristate Enable: When the input is left OPEN or tied to logic “1”, the
normal oscillation occurs. When the input is Grounded (tied to logic
“0”), the output is in high impedance state. The input has an internal
pull-up resistor thus allowing the input to be left open.
Storage Temperature: The temperature range where the unit is
safely stored without damaging or changing the performance of the
Output Logic: The output of an oscillator is designed to meet
various specified logic states, such as TTL, HCMOS, ECL, Sine,
Clipped-Sine (DC cut).
Frequency vs. Power Supply Variation: Maximum frequency change
allowed when the power supply voltage is changed within its specified
limits (typical ± 10% in VCC or ± 5% change).
Harmonic Distortion: The non-linear distortion due to unwanted
harmonic spectrum component related with target signal frequency.
Each harmonic component is the ratio of electric power against
desired signal output electric power and is expressed in terms of dBc,
i.e. -20dBc. Harmonic distortion specification is important especially
in sine output when a clean and less distorted signal is required.
Supply Voltage (Vdd max): The maximum voltage which can safely
be applied to the Vcc terminal with respect to ground. Maximum
supply voltage for TTL is 5.5V and for HCMOS is 7V.
Input Voltage (VIN): The maximum voltage that can be safely applied
to any input terminal of the oscillator.
Output HIGH voltage (VOH): The minimum voltage at an output of
the oscillator under proper loading.
Phase Noise:
The measure of the short-term frequency
fluctuations of the oscillator. It is usually specified as the single side
band (SSB) power density in a 1Hz bandwidth at a specified offset
frequency from the carrier. It is measured in dBc/Hz.
Output LOW voltage (V0H): The maximum voltage at an output of
the oscillator under proper loading.
Input HIGH voltage (VIH): The minimum voltage to guarantee
threshold trigger at the input of the oscillator.
Input LOW voltage (VIL): The maximum voltage to guarantee the
threshold trigger at the input of the oscillator.
Supply Current (lcc): The current flowing into Vcc terminal with
respect to ground. Typical supply current is measured without load.
Figure 1.
Symmetry or Duty Cycle: The symmetry of the output waveform at
the specified level (at 1.4V for TTL, at 1/2 Vcc for HCMOS, or 1/2
waveform peak level for ECL).See Fig. 1
SYM = tH x 100 (%)
Fan Out: The measure of driving ability of an oscillator, expressed
as the number of inputs that can be driven by a single output. It can
be represented by an equivalent load capacitance (CL) or a TTL load
circuit consisting of diodes, load resistor, and a capacitor.
Stand By: A function that temporary turns off the oscillator and other
dividers to save power. Logic “0” will enable stand by mode. The
disable current at stand by mode varies from a few micro-amperes to
tens of micro-amperes (5μA typical). Because oscillation is halted,
there is a maximum of 10 ms (same amount of start-up time) before
output stabilizes.
ISO 9001 / QS 9000
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