Common problem

1. Incorrect selection of material parameters leads to failure of crystal oscillator

For example, a MCU needs to match 32.768KHz of 6pF. As a result, 12.5pF is selected, resulting in no vibration.

Solution: replace the specification and model that meet the requirements. If necessary, please confirm with the original MCU factory or us.

2. The internal crystal plate is broken or damaged, resulting in no vibration

The crystal chip inside the crystal oscillator is damaged due to damage during transportation, or falling, impact and other factors during use, resulting in the failure of the crystal oscillator.

Solution: replace the crystal oscillator. What we should pay attention to at ordinary times is that foam should be thicker in the transportation process to avoid damage halfway. Drop, heavy pressure, impact, etc. shall be avoided in the process. In case of any of the above circumstances, it is prohibited to use it again.

3. The mismatch of oscillation circuit leads to the failure of crystal oscillator

There are three indexes that affect the oscillation circuit: frequency error, negative impedance and excitation level.

The frequency error is too large, resulting in the deviation of the actual frequency from the nominal frequency, resulting in the failure of the crystal oscillator.

Solution: select products with appropriate ppm value.

If the negative impedance is too large or too small, the crystal oscillator will not vibrate.

Solution: if the negative impedance is too large, you can increase the values of crystal oscillator external capacitors CD and CG to reduce the negative impedance; If the negative impedance is too small, the values of crystal oscillator external capacitors CD and CG can be reduced to increase the negative impedance. Generally speaking, the negative impedance value shall not be less than 3-5 times the nominal maximum impedance of the crystal oscillator.

If the excitation level is too large or too small, the crystal oscillator will not vibrate

Solution: adjust the excitation level of the oscillation circuit to the crystal oscillator output by adjusting the size of RD in the circuit. Generally speaking, the smaller the excitation level, the better. In addition to the low processing power consumption, it is also related to the stability of the oscillation circuit and the service life of the crystal oscillator.

4. Common crystal oscillator anomalies common crystal oscillator anomalies

Solution: Generally speaking, metal encapsulated products are superior to ceramic encapsulated products in anti electromagnetic interference. If the EMC on the circuit is large, metal encapsulated products shall be selected as far as possible. In addition, do not take the signal line under the crystal oscillator to avoid.