ATXMEGA8E5_14 datasheet(22/147 Pages) ATMEL

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XMEGA E5 [DATASHEET]

Atmel-8153I–AVR-ATxmega8E5-ATxmega16E5-ATxmega32E5_Datasheet–08/2014

1kHz output. The oscillator is automatically enabled/disabled when it is used as clock source for any part of the device.

This oscillator can be selected as the clock source for the RTC.

11.3.2 32.768kHz Calibrated Internal Oscillator

This oscillator provides an approximate 32.768kHz clock. It is calibrated during production to provide a default frequency

close to its nominal frequency. The calibration register can also be written from software for run-time calibration of the

oscillator frequency. The oscillator employs a built-in prescaler, which provides both a 32.768kHz output and a 1.024kHz

output.

11.3.3 32.768kHz Crystal Oscillator

A 32.768kHz crystal oscillator can be connected between the TOSC1 and TOSC2 pins and enables a dedicated low

frequency oscillator input circuit. A low power mode with reduced voltage swing on TOSC2 is available. This oscillator

can be used as a clock source for the system clock and RTC, and as the DFLL reference clock.

11.3.4 0.4 - 16MHz Crystal Oscillator

This oscillator can operate in four different modes optimized for different frequency ranges, all within 0.4 - 16MHz.

11.3.5 8MHz Calibrated Internal Oscillator

The 8MHz calibrated internal oscillator is the default system clock source after reset. It is calibrated during production to

provide a default frequency close to its nominal frequency. The calibration register can also be written from software for

run-time calibration of the oscillator frequency. The oscillator employs a built-in prescaler, with 2MHz output. The default

output frequency at start-up and after reset is 2MHz. A low power mode option can be used to enable fast system wake-

up from power-save mode. In all other modes, the low power mode can be enabled to significantly reduce the power

consumption of the internal oscillator.

11.3.6 32MHz Run-time Calibrated Internal Oscillator

The 32MHz run-time calibrated internal oscillator is a high-frequency oscillator. It is calibrated during production to

provide a default frequency close to its nominal frequency. A digital frequency looked loop (DFLL) can be enabled for

automatic run-time calibration of the oscillator to compensate for temperature and voltage drift and optimize the oscillator

accuracy. This oscillator can also be adjusted and calibrated to any frequency between 30MHz and 55MHz.

11.3.7 External Clock Sources

The XTAL1 and XTAL2 pins can be used to drive an external oscillator, either a quartz crystal or a ceramic resonator.

XTAL1 or pin 4 of port C (PC4) can be used as input for an external clock signal. The TOSC1 and TOSC2 pins are

dedicated to driving a 32.768kHz crystal oscillator.

11.3.8 PLL with 1x-31x Multiplication Factor

The built-in phase locked loop (PLL) can be used to generate a high-frequency system clock. The PLL has a user-

selectable multiplication factor of from 1 to 31. In combination with the prescalers, this gives a wide range of output

frequencies from all clock sources.

ATXMEGA8E5 Datasheet(PDF) 22 Page - ATMEL Corporation