About Drive Level of smd oscillator
About Drive Level of smd oscillators
Drive level of smd oscillator: refers to the power consumption value of smd oscillator.
The degree of drive level directly effect the performance of smd oscillators.
So the circuit designer must be careful about the input value requirement and make sure it is in the required range to ensure the normal work of smd oscillators.
The drive level is generally in micro watt. In recent years, with the rapid improvement of smd oscillator production process and technology,
as well as the higher requirements of electronic products for smd oscillator in miniaturization and low power consumption,
smd oscillator with higher drive level gradually tends to be marginalized in some small electronic product applications.
Excessive drive level provided by the circuit may lead to the following defects of smd oscillator:
The amplitude of the quartz crystal becomes larger, so too much heat is generated and the temperature in the vibration area of the quartz crystal increases.
However, the temperature gradient of the quartz crystal will rise, which will directly destroy the frequency stability.
The mechanical deformation of the wafer may exceed the elastic limit, resulting in irrecoverable displacement of the crystal lattice
and permanent frequency offset of the smd oscillator output frequency. In more serious cases, the quartz wafer is broken,
leading to the complete failure of the smd oscillator (stop vibration), which is what we call "smd oscillator dead".
The equivalent resistance becomes larger (Note: the resistance of smd oscillator is generally 10 ~ 100 Ω),
which affects the start-up of smd oscillator and causes the stop of smd oscillator in serious cases.
As a result, the conductive adhesive fixed to the wafer and the base is damaged, such as broken,
and the internal circuit of the smd oscillator is open and the smd oscillator stops.
As a result, the Q value decreases, the resistance temperature characteristics and
frequency temperature characteristics become irregular, which leads to the instability of crystal frequency.
As a result, the parasitism changes, leading to crystal frequency hopping, unable to provide standard frequency.
Accelerate the aging attenuation of smd oscillator in terms of performance, resulting in the instability of smd oscillator accuracy.
If the drive level is too small, it may bring bad hidden trouble to the smd oscillator:
The smd oscillator is not easy to start or stop, so it loses the function of providing frequency signal.
It affects the stability of smd oscillator, and can not guarantee the output of stable accurate frequency signal, resulting in IC capture signal failure.
Therefore, in the use of smd oscillator, we must pay attention to the following two points:
According to the different application fields, the smd oscillator with appropriate drive level should be selected;
In order to change the output frequency of the smd oscillator, we must not arbitrarily change the drive level input to the smd oscillator by the circuit.