Epson crystal oscillator agent for your fans crystal oscillator frequency temperature difference on the impact of the circuit
Release date:2018-12-24 Author:Guan Shuo Click:
The influence of crystal oscillator frequency and temperature difference on the circuit is analyzed by Epson crystal oscillator agent.
1. The matching of quartz resonator in the circuit is not ideal, which affects the use effect.
Crystal resonators have matching capacitors and self-loading capacitors.
Matched Capacitance - Load Capacitance refers to the capacitance needed for crystal oscillation to oscillate normally. Generally, the external capacitance is used to make the equivalent capacitance at both ends of the crystal oscillator equal to or close to the load capacitance. In the case of high requirement, the ground capacitance of IC input terminal should also be considered. Generally, the capacitance at both ends of the crystal oscillator is twice the load capacitance required. In this way, the parallel connection is close to the load capacitor.
Load capacitance refers to the total external effective capacitance across both ends of a crystal in a circuit. It is not only a test condition, but also a use condition. In general, the precise frequency can be obtained by adjusting the value of load capacitance in application. The magnitude of the capacitor mainly affects the resonant frequency of the load and the equivalent load resonant resistance. Imperfect matching capacitance often affects the crystal oscillator performance.
2. The temperature drift of crystal oscillator is too large, which even affects the performance of the product.
When the crystal oscillator is heated or lowered to a certain temperature and then lowered to normal temperature, there will be a certain change compared with the initial test at normal temperature. This is because the thermal hysteresis phenomenon of the crystal is generally small, and the deviation is about 10-7 to-9 levels. Or if the crystal oscillator is not properly used at its own operating temperature, the problem of crystal oscillation will also occur frequently. For example, the working temperature of crystal oscillator for civil consumption is generally - 20 -+70 (?) C. When the temperature is - 25 (?) C, the frequency deviation varies greatly and increases by about 50 ppm or more. The crystal oscillation will be unstable. However, many engineers lack enough attention and understanding of crystal oscillator, and once something goes wrong, they are at a loss.