ATXMEGA128A4_09 Datasheet, PDF (20/104 Pages) ATMEL Corporation – 8/16-bit XMEGA A4 Microcontroller

XMEGA A4
10.3.3
10.3.4
10.3.5
10.3.6
10.3.7
10.3.8
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.
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.
2 MHz Run-time Calibrated Internal Oscillator
The 2 MHz Run-time Calibrated Internal Oscillator is a high frequency oscillator. It is calibrated
during production 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.
32 MHz Run-time Calibrated Internal Oscillator
The 32 MHz Run-time Calibrated Internal Oscillator is a high frequency oscillator. It is calibrated
during production 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.
External Clock input
The external clock input gives the possibility to connect a clock from an external source.
PLL with Multiplication factor 1 - 31x
The PLL provides the possibility of multiplying a frequency by any number from 1 to 31. In com-
bination with the prescalers, this gives a wide range of output frequencies from all clock sources.
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