Crystals over 30 MHz (up to >200 MHz) are normally operated at series resonance in which the impedance appears at its minimum and equal for the series resistance. For these crystals the sequence resistance is specified ( Attributes a number of frequencies, crystal ageing, and running temperature ranges that will https://bookmarkchamp.com/story18939063/5-tips-about-smd-crystal-oscillators-you-can-use-today