Renesas RA Family
RA2 Quick Design Guide
R01AN6060EU0100 Rev.1.00
Page 13 of 44
Sep.14.21
Table 5. RA2 Oscillators
Oscillator
Input Source
Frequency
Primary Uses
Main clock
*4
(MOSC)
External
crystal/resonator
-or-
1 MHz to 20 MHz
*3
Main system clock (ICLK), Peripheral
clocks, CAN clock, CAC clock,
CLKOUT, flash clock
*3
, SDADC
clock
*1
External clock
Up to 20 MHz
Sub-clock
*4
(SOSC)
External
crystal/resonator
32.768 kHz
Real-time clock, main system clock
(ICLK) in low power modes,
CLKOUT, AGT clock, CAC clock,
Real-time clock
High-speed on-chip
(HOCO)
On-chip oscillator
24/32/48/64 MHz
Main system clock (ICLK), Peripheral
clocks, CAC clock, CLKOUT, USB
clock
*2
, SDADC clock
*1
Middle-speed on-
chip (MOCO)
On-chip oscillator
8 MHz
Main system clock (ICLK) at startup,
Peripheral clocks, CLKOUT, CAC
clock
Low-speed on-chip
(LOCO)
On-chip oscillator
32.768 kHz
Main system clock (ICLK) in low
power modes and during main
oscillator stop detection, Peripheral
clocks, Systick timer, AGT clock,
CLKOUT, CAC clock, Real-time
clock, Independent Watchdog Timer
clock
Independent
Watchdog (IWDT)
On-chip oscillator
15 kHz
Independent Watchdog Timer clock,
CAC clock
Note 1: SDADC clock is only present on RA2A1 devices.
2: USB clock is only present on RA2A1 devices.
3: On RA2A1 devices, the flash clock (FCLK) is driven independently from MOSC, and can be
sourced from MOSC, SOSC, HOCO, MOCO, or LOCO.
4: Not present on RA2E2
Some devices, such as RA2E2, do not include the option for an external crystal or clock. In this case, the
oscillator sources for the main clock are limited to the on-chip oscillators.
5.1 Reset Conditions
After reset, RA2 MCUs begin running with the middle-speed on-chip oscillator (MOCO) as the main clock
source. At reset, the main oscillator is stopped by default. The HOCO and IWDT may be on or off depending
on the settings in the Option Setting Memory (see section 4).
5.2 Clock Frequency Requirements
Minimum and maximum frequencies are shown in the following tables. Details can be found in the
“Overview” section of the “Clock Generation Circuit” chapter in the MCU Hardware User’s Manual, including
external and internal clock source specifications. Additional details can be found in the “AC Characteristics”
section of the “Electrical Characteristics” chapter in the MCU Hardware User’s Manual.
Table 6. Frequency Range for RA2 MCU Internal Clocks
ICLK
4
PCLKB
PCLKD
FCLK
1
UCLK
2
CANMCLK
3
Maximum Frequency [MHz]
48
32
64
32
48
20
Minimum Frequency [MHz]
1
48
1
Note 1: Only on RA2A1. The FCLK must run at a frequency of at least 1 MHz when programming or
erasing ROM or data flash.
2: For devices with USB peripheral function.
3: For devices with CAN peripheral function.
4: For RA2E1, RA2E2 and RA2L1, ICLK must run at a frequency of at least 1 MHz when
programming or erasing ROM or data flash.
