atxmega128d4-mh ATMEL Corporation, atxmega128d4-mh Datasheet - Page 18

• Manufacturer Part Number: atxmega128d4-mh
• Description: 8/16-bit Xmega D4 Microcontroller
• Manufacturer: ATMEL Corporation

9.3
9.3.1
9.3.2
8135F–AVR–02/10
Clock Options
32 kHz Ultra Low Power Internal Oscillator
32.768 kHz Calibrated Internal Oscillator
Figure 9-1.
Each clock source is briefly described in the following sub-sections.
The 32 kHz Ultra Low Power (ULP) Internal Oscillator is a very low power consumption clock
source. It is used for the Watchdog Timer, Brown-Out Detection and as an asynchronous clock
source for the Real Time Counter. This oscillator cannot be used as the system clock source,
and it cannot be directly controlled from software.
The 32.768 kHz Calibrated Internal Oscillator is a high accuracy clock source that can be used
as the system clock source or as an asynchronous clock source for the Real Time Counter. It is
calibrated during production to provide a default frequency which is close to its nominal
frequency.
Run-Time Calibrated
Run-time Calibrated
Calibrated Internal
Internal Oscillator
Internal Oscillator
Internal Oscillator
Crystal Oscillator
Crystal Oscillator
0.4 - 16 MHz
32 kHz ULP
32.768 KHz
32.768 kHz
Clock Input
Oscillator
External
32 MHz
2 MHz
Clock system overview
CLOCK CONTROL
with PLL and
Prescaler
UNIT
clk
clk
clk
clk
RTC
PER
CPU
ULP
PERIPHERALS
NVM MEMORY
XMEGA D4
INTERRUPT
WDT/BOD
EEPROM
PORTS
EVSYS
FLASH
RAM
ADC
CPU
RTC
...
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