If the crystal does not vibrate, you can try permuting and combining the following aspects to find the links that are prone to problems, and thinking about the problems that you have, it is easier to find the cause of the failure.

1. Crystal excitation power

We all know that quartz crystal oscillator is a passive component, and it will work normally only when IC provides certain excitation power. Therefore, this excitation power is an important part of the branch plant. If the excitation power is too low, the crystal oscillator is not easy to generate a signal, and it is not easy to start oscillation. However, if the excitation power is too high, over-excitation will be formed, which will easily cause damage to the quartz chip and cause the phenomenon of vibration stop. To solve the problem that the crystal does not oscillate, at least the following three elements must be tested: the oscillation frequency (frequency matching), the oscillation margin (negative impedance) and the excitation power are tested.

2. The brand and load capacitance of the crystal oscillator

The load capacitance is very important. The load capacitance refers to the sum of all the effective capacitances inside and outside the IC block connected by the two leads of the crystal oscillator. The brand of the crystal oscillator is also one of the factors that can not measure the vibration. The original authentic crystal brand is relatively safe. For example, EPSON clock chip RX8010SJ

3. Grounding mode of crystal pin

The shell of the crystal oscillator is made of metal. When packaging, the pad can be made into a mechanical pad and suspended, and the top of Vanke can be fixed with iron wire and grounded (grounding is mainly to avoid electromagnetic interference of the circuit, because some circuits are not reasonable when wiring. It is very easy to cause electromagnetic interference and cause problems with the crystal oscillator)

4. Reduce heating time during crystal welding

Check whether the welding temperature of the crystal oscillator is high, which will cause the second damage to the crystal oscillator. Generally, the welding temperature is required to be about 250 degrees or lower, and the maximum temperature should not exceed 300 degrees. If these are within the required scope, then we have to consider whether there are other reasons.

5. Use an active crystal

It is best to use an active crystal oscillator. Active crystal oscillators are all built-in circuits, so there is no circuit matching problem, which greatly avoids the problem of crystal oscillator not being able to oscillate. This is one of the best ways to solve the problem of crystal oscillator not vibrating!