|
What is…?
|
Explanations
|
Frequency Range
|
The center frequency of a crystal resonator.
|
|
Vibration mode
|
High frequency (MHz range) AT-cut crystals vibrate in the thickness-shear vibration, which can be excited in fundamental or odd overtone mode. The mode of operation of a quartz crystal will determine the frequency of oscillation.
|
|
Frequency Tolerance at 25C
|
The tolerance is the maximum allowable deviation from nominal frequency at a specified temperature (typically 25 degree C). It is normally specified in parts per million (ppm) or percentage of nominal frequency. The overall frequency tolerance is the maximum allowable deviation from nominal frequency due to changes in temperature, time and all other environmental conditions.
|
|
Frequency Stability in operating temperature range
|
Frequency stability is the maximum allowable deviation from the nominal frequency over a specified temperature range, and is specified in parts per million (ppm) or percentage of nominal frequency. Deviation is usually referenced to the measured frequency at 25 degree C. This parameter depends on the following factors: types of quartz cut, angle of the quartz cut, mode of operation, and mechanical dimensions of the quartz blank.
|
|
Load Capacitance
|
Load capacitance is specified in pico Farads (pF). When an oscillator circuit presents some amount of load capacitance to a crystal, the crystal is operated at the condition of “Parallel Load Resonance”, and a value of load capacitance must be specified. Typical values of load capacitance are 18pF, 20pF, 22pF, 30pF and 32pF.
|
|
Operating temperature range
|
Operating temperature range is the temperature range within which output frequency stability and other electrical, environment characteristics meet the specifications.
|
|
Storage temperature range
|
The storage temperature range applies to minimum and maximum temperatures that the devices can be stored or exposed to when in a non-oscillation state. After exposing or storing the device at the minimum or maximum temperatures for a length of time, all of the operating specifications are guaranteed over the specified operating temperature range.
|
|
Equivalent series resistance
|
ESR is the resistive element, measured in Ohms, of quartz crystal resonator. Generally, the lower the resistance value of a crystal, the more active it is and less drive is required to activate it. However, lower values than those standard specifications will results in a unit cost increase due to the additional processes required to achieve those ESR values.
|
|
Drive Level
|
The drive level, expressed in microwatts or milliwatts, is the power dissipation level at which the crystal resonator is designed to operate. Maximum power is the most power a crystal resonator can dissipate while still maintaining operation with all electrical parameters guaranteed.
|
|
Shunt Capacitance
|
The shunt capacitance of a crystal is due in part to the thickness of the wafer. This is the measure capacitance while not vibrating. Shunt capacitance range from 1 to 7 pF. It is not typical to exceed 7 pF due to compatibility with the oscillator circuit.
|
|
Aging
|
Aging of a quartz crystal is a measure of the frequency stability over an extended time period and is usually expressed in terms of parts per million (ppm) per day or year. It applies to the cumulative process which contributes to the deterioration of the crystal unit and which results in a permanent change in operating frequency of the crystal unit.
|