Are the CST and CSTCC series resonators polarized?
Theoretically, CST and CSTCC resonators are basically the same regardless of direction. In practice, this is not exactly the case. Murata does show the CST and CSTCC resonators with polarity for the following two reasons: (1) in mass production of the ceramic resonator, the resonator is only sorted in one polarity direction per specification. (2) the two internal load capacitors ( of a given part sample ) are typically not the exact same value (spec tolerance on value id +/-20% in most cases ). Assuming the two internal load caps are of slight different value within tolerance, it is possible for the oscillation frequency to be slightly different depending on which way the resonator is oriented in the circuit. Due to this, using the ceramic resonator in the opposite polarity (as indicated in the part specification) has some chance for the resulting initial oscillation frequency not being within specification.
