7 Designing the Clocking Subsystem

In addition to the power subsystem, the clocking subsystem needs to be designed to provide appropriate clocks to all ICs in the system. These clocks can be created by pairing crystals with internal oscillators within the system ICs, or they can be created by a separate clock generator. For your design, see the information below on designing the clocking subsystem.

Key Considerations:

• The device operation requires one or more of the following clocks:
  • A 32k optional crystal as an optional clock source for the RTC.
  • Two HF crystals, SYS_CLKIN1 (mandatory) with either 19.2, 20, or 27 MHz and SYS_CLKIN2 (optional) with 19.2-32 MHz quartz or 12-38.4 MHz CMOS square clock source as reference clocks for system operation.
• For more details, see the Clocking sections of the device-specific data sheet and TRM.