49.6.2 Crystal Oscillator

Figure 49-7. Crystal Oscillator Schematic

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

Note: Crystal selection must be done using both the crystal data sheet and the crystal oscillator parameters given in the XOSC Electrical Specifications from Electrical Characteristics chapter.
Table 49-4. Crystal Oscillator Checklist
Signal Name Recommended Pin Connection Description
XIN Load capacitor. (1,2) External Crystal

Crystal frequency range specified in the XOSC Electrical Specifications (XOSC_1 parameter)
XOUT Load capacitor. (1,2)
Note:
  1. The capacitors should be placed close to the device.
  2. Use the equation in chapter XOSC Electrical Specifications to calculate the load capacitor.

32.768 kHz External Clock Source

Figure 49-8. 32.768 kHz External Clock Source Schematic
Table 49-5. External Clock Source Connections
Signal Name Recommended Pin Connection Description
XIN32 Connect to an external clock signal

Frequency range specified in the XOSC32K Electrical Specifications (XOSC32K_19 parameter)

 Input for external clock signal
XOUT32/GPIO Can be left unconnected or used as normal GPIO NC/GPIO