45.5.2 Crystal Oscillator

The following figure illustrates a typical example of the crystal oscillator schematic:

Figure 45-7. Crystal Oscillator Schematic

The crystal must be located as close as possible to the device. Long signal lines may cause a load too high to operate the crystal, and cause crosstalk to other parts of the system.

Table 45-5. Crystal Oscillator Checklist
Signal NameRecommended Pin ConnectionDescription
XINLoad capacitor CLEXT(1)(2)External crystal between 0.4 to 32 MHz
XOUTLoad capacitor CLEXT(1)(2)
  1. Use the equation in Crystal Oscillator Characteristics to calculate CLEXT.
  2. Decoupling capacitor should be placed close to the device for each supply pin pair in the signal group.