Crystals over 30 MHz (as much as >200 MHz) are usually operated at series resonance exactly where the impedance appears at its minimum and equivalent into the collection resistance. For these crystals the collection resistance is specified ( Predecessor of surface mount know-how but nevertheless useful in selected situations, such https://bookmarkingdelta.com/story18959677/not-known-factual-statements-about-smd-crystal-oscillators