Electronic – What loading capacitor do I use for the crystal


I am using this crystal (the 7.3728 MHz variant).

The datasheet specifies a 5pF to 55pF load capacitance; is this really so? I was under the impression that most quartz crystals had an optimal capacitance which was fairly critical for oscillation.

In my design, I have specified 18pF based on another crystal (of the same frequency and nearly the same specifications), which is not available at the moment. In that case, the datasheet clearly specified 18pF.

If it matters, I am using a dsPIC33FJ128GP804 microcontroller/DSP.

Best Answer

The crystal manufacturer (ACT) can make crystals with any load capacitance in that range.

This page states that it is 30 pF for the crystals supplied to Rapid Electronics:


That isn't the actual value you use for the feedback capacitors, of course. They are effectively in series.