Renesas RA Family
RA2 Quick Design Guide
R01AN6060EU0100 Rev.1.00
Page 12 of 44
Sep.14.21
Figure 7.
Option
Memory
Settings
in FSP Configuration for RA
2A1
MCU
5. Clock Circuits
Most RA2 MCUs have six primary oscillators. Five of these may be used as the source for the main system
clock. The remaining oscillator is dedicated to the Independent Watchdog Timer. In a typical system, the
main clock is driven with an external crystal or clock.
This input is directed to internal selectors and frequency
dividers, where it is further directed to the main system clock (ICLK), flash clock, CPU clock, and peripheral
module clocks. For some devices, the clock distribution also includes additional clocks for ADC and USB
peripherals. Note that RA2E2 devices do not have external crystal or clock input pins. Refer to the Hardware
User’s Manual “Clock Generation Circuit” chapter for the block diagram of the clock generation circuit.
Each clock has specific tolerances and timing values. Refer to the Hardware User’s Manual “AC
Characteristics” section in the “Electrical Characteristics” chapter for the Frequency and Clock Timing
specifications. Refer to the Hardware User’s Manual “Clock Generation Circuit” chapter for the relationship
between the various clock frequencies.