84
8331B–AVR–03/12
Atmel AVR XMEGA AU
Figure 7-1.
The clock system, clock sources, and clock distribution.
Real Time
Counter
Peripherals
RAM
AVR CPU
Non-Volatile
Memory
Watchdog
Timer
Brown-out
Detector
System Clock Prescalers
USB
Prescaler
System Clock Multiplexer
(SCLKSEL)
PLLSRC
RTCSRC
DI
V
3
2
32 kHz
Int. ULP
32.768 kHz
Int. OSC
32.768 kHz
TOSC
2 MHz
Int. Osc
32 MHz
Int. Osc
0.4 – 16 MHz
XTAL
DI
V
3
2
DI
V
3
2
DI
V
4
XOSCSEL
PLL
USBSRC
TOS
C1
TOS
C2
XTAL1
XTAL2
clk
SYS
clk
RTC
clk
PER2
clk
PER
clk
CPU
clk
PER4
clk
USB
