Atmel XMEGA A3 series

19
8068C–AVR–06/08
XMEGA A3
10.3.3 32.768 kHz Crystal Oscillator
The 32.768 kHz Crystal Oscillator is a low power driver for an external watch crystal. It can be
used as system clock source or as asynchronous clock source for the Real Time Counter.
10.3.4 0.4 - 16 MHz Crystal Oscillator
The 0.4 - 16 MHz Crystal Oscillator is a driver intended for driving both external resonators and
crystals ranging from 400 kHz to 16 MHz.
10.3.5 2 MHz Run-time Calibrated Internal Oscillator
The 2 MHz Run-time Calibrated Internal Oscillator is a high frequency oscillator. It is calibrated
during protection to provide a default frequency which is close to its nominal frequency. The
oscillator can use the 32 kHz Calibrated Internal Oscillator or the 32 kHz Crystal Oscillator as a
source for calibrating the frequency run-time to compensate for temperature and voltage drift
hereby optimizing the accuracy of the oscillator.
10.3.6 32 MHz Run-time Calibrated Internal Oscillator
The 32 MHz Run-time Calibrated Internal Oscillator is a high frequency oscillator. It is calibrated
during protection to provide a default frequency which is close to its nominal frequency. The
oscillator can use the 32 kHz Calibrated Internal Oscillator or the 32 kHz Crystal Oscillator as a
source for calibrating the frequency run-time to compensate for temperature and voltage drift
hereby optimizing the accuracy of the oscillator.
10.3.7 External Clock input
The external clock input gives the possibility to connect a clock from an external source.
10.3.8 PLL with Multiplication factor 2 - 31x
The PLL provides the possibility of multiplying a frequency by any number from 2 to 31. In com-
bination with the prescalers, this gives a wide range of output frequencies from all clock sources.