Electronic engineers will also be confused when selecting crystal oscillators, and do not know whether the selected crystal oscillators can be applied to the product. As we all know, the role of the crystal oscillator is to form an oscillation circuit, generate an oscillation signal that is required for the work of the appliance and the frequency is stable, which is used to control the normal operation of the appliance.
However, in practice, it is necessary to select the appropriate crystal oscillator according to the type of oscillation circuit, otherwise the electrical appliance will be abnormal or unable to work due to improper use or selection of the crystal oscillator. The selection of chip crystal oscillators should follow the following 6 principles.
1. Surface viewing. See if the label text of the chip crystal oscillator shell is clear and standardized, whether there is a crack, whether the pin has been soldered with tin, if a defect in the crystal oscillator is found from the appearance, it should not be used.
2. Select the model. The selected chip crystal oscillator can see the model mark of the shell, the model indicates the performance of multiple parameters of the crystal oscillator, if the crystal oscillator model is not selected properly, it will lead to a mismatch between the product application and cannot work properly.
3. Select the resonant frequency. The selected chip crystal oscillator carefully considers whether the resonant frequency is suitable for the requirements of the actual circuit. If the oscillation circuit requires 4. 43。 For MHz crystal oscillators, it is absolutely impossible to choose a crystal oscillator with a resonant frequency of 500KHZ.
4. Select the load capacitor. After the selected chip crystal oscillator selects the resonant frequency, special attention should be paid to the load capacitance properties of the quartz crystal oscillator to distinguish whether it is a low load capacitance type or a high load capacitance type. Only if the two parameters of resonant frequency and load capacitance meet the needs of the actual circuit at the same time, the choice is correct. If there is one parameter that does not meet the requirements, it is the wrong choice.
5. Select the type of crystal oscillator. In the selection of SMT crystal oscillators to consider the type, that is, to find out whether the crystal oscillators are series resonant or parallel resonant. The series resonant crystal oscillator is a low load capacitance, and the parallel resonant crystal oscillator is a high load capacitance, if the previous step is correct, then the type of crystal oscillator selected is also in line.
6. The replacement principle of crystal oscillator. If a crystal oscillator is damaged, in principle, the original crystal oscillator should be replaced. In the absence of the original model, consider replacing it with another model or other type of crystal oscillator.
In short, crystal oscillator selection is not only about parameter performance, but also about delivery, price and supply stability.
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