Hi Team,
Issue: the monolithic information is lost or erased.
The crystal output frequency is 19.999992 MHz at the time of power-up, which meets the 20 MHz ± 10 Hz requirement. The crystal output frequency is 20.000092 MHz after operating for some time, which does not meet the crystal output frequency range and is changing continuously.
Regarding the crystal:
A. The normal performance metrics test is good and the frequency is normal.
B. Temperature characterization test of the product -- the specification document requires the temperature characteristic ≤ 0.5 ppm, and the product test results are as follows:
The product has large fluctuations in frequency between low temperature and around -8 to 5 °C and normal temperature between 35 to 50 °C, while the frequency returns to normal when the temperature exceeds 50 °C.
C. Read data from product communication and internal items, and the product communication is normal. Reading the internal monolithic compensation data reveals that data has been erased (data in the red box becomes 0).
Below are the figures of working and non-working products:
Figure 1. Non-working Product Monolithic Information
Figure 2. Working Product Monolithic Information
The product temperature characteristic frequency is normal after rewriting data to the non-working’s monolithic device. The impedance test was conducted on the pins of working and non-working monolithic units and no difference in impedance was found:
Could you please help check this case? Thanks.
Best Regards,
Cherry
