32.768KHZ is also called a Real-Time Clock crystal, and RTC is also the manifestation of a 32.768KHZ real-time clock. Its function is to generate a timing circuit reference signal, including all real-time clock crystal RTC, which are generally 32.768 or its multiples. 32.768KHZ crystals are divided into direct plug-in and patch. The 32.768KHZ direct plug-in crystal has only 2 pins, both of which are functional pins, and there is no ground pin; the 32.768KHZ patch crystal depends on how many pins there are. If there are only two pins, it is the same as the direct plug-in. If there are 4 pins, determine which two functional pins are on the homepage, and the other two pins can be grounded or left floating. If it is an active crystal, the four pins are SPXO, TCXO, VC-TCXO, and VCXO, then one of their pin definitions is GND, and it is OK to directly connect to the ground.

If the crystal does not oscillate, you can try to arrange and combine the following aspects to find the links that are prone to problems. Combined with your own problem points, it is easier to find the reason for the non-oscillation.

https://www.weetcap.com/Crystals-Oscillators/WEET-WQC-TF3215-32.768KHz-SMD-Tuning-Fork-Crystal.html

1. Crystal excitation power

We all know that the crystal is a passive component, which mainly requires a certain excitation power provided by the IC to work normally. Therefore, this excitation power is an important part of the branch factory. If the excitation power is too low, the crystal will not easily generate a signal, and it will not be easy to oscillate. However, if the excitation power is too high, it will form over-excitation, which will easily cause damage to the quartz chip, resulting in the phenomenon of stopping oscillation. To solve the problem of crystal not oscillating, at least the following three factors must be tested: oscillation frequency (frequency matching), oscillation margin (negative impedance) and excitation power.

2. Brand and load capacitance of crystal

Load capacitance is very important. Load capacitance refers to the sum of all effective capacitances inside and outside the two leads of the crystal connected to the IC block. WEET brand is a reliable and trustful supplier, popular 32.768KHZ crystals: WQC-TF206,WQC-TF308,WQC-TF1610,WQC-TF2012,WQC-TF3215,WQC-TF7015,WQC-TF2060,WQC-TF3080,WQC-TF7015

3. Grounding method of crystal pin

The shell of the crystal is metal. When packaging, the pad can be made into a mechanical pad and left hanging. The iron wire is fixed to the top of the Vanke and then grounded (grounding is mainly to avoid electromagnetic interference of the circuit, because some circuits are not reasonable during wiring, which can easily cause electromagnetic interference and cause problems with the crystal)

4. Reduce the heating time when the crystal is welded

Check whether the welding temperature of the crystal is high, causing secondary damage to the crystal, and do not exceed the required welding temperature.

5. Use active crystal oscillator

Active crystal oscillators are all built-in circuits, so there is no circuit matching problem, which greatly avoids the occurrence of crystal oscillator non-oscillation problems.

 WEET popular series:
 WQS-OSC3225,WQS-OSC5032,WQS-OSC7050,WQS-3Z3225,WQS-5Z5032,WQS-7Z7050