QUARTZ_CRYSTAL_SPECIFICATIONS

Published:2009/7/12 23:49:00 Author:May | From:SeekIC

Five main parameters control the characteristics of a crystal, as noted in the equivalent circuit for the figure. These parameters are: ● C1, the motional capacitance● L1, the motional inductance● R1, the equivalent series resistance (ESR)● C0, the parallel capacitance resulting from the electrodes and crystal packaging● CL, external load capacitanbe of the circuit C1 and L1 are interdependent because they determine the resonant frequency of the crystal. If we know one of the parameters, we can readily compute the other if we know the series resonant frequency. R1 is the resistance determined by the motional (piezoelectric) behavior of the crystal. If it is too high, the crystal might not start oscillation. C0 is a physical capacitor, created by the electrodes plated onto the crystal surface, along with some additional capacitance from the package. Generally, larger C0 contributes to better pullability. CL is the load capacitance of the user's circuit. The crystal must operate at the right frequency in the intended circuit, so this value needs to be included in the crystal purchase specification.



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