ATxmega256A3U Atmel Corporation, ATxmega256A3U Datasheet - Page 18

• Manufacturer Part Number: ATxmega256A3U
• Manufacturer: Atmel Corporation

Specifications of ATxmega256A3U

• Flash (kbytes): 256 Kbytes
• Pin Count: 64
• Max. Operating Frequency: 32 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 50
• Ext Interrupts: 50
• Usb Transceiver: 1
• Usb Speed: Full Speed
• Usb Interface: Device
• Spi: 10
• Twi (i2c): 2
• Uart: 7
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 16
• Adc Resolution (bits): 12
• Adc Speed (ksps): 2000
• Analog Comparators: 4
• Resistive Touch Screen: No
• Dac Channels: 2
• Dac Resolution (bits): 12
• Temp. Sensor: Yes
• Crypto Engine: AES/DES
• Sram (kbytes): 16
• Eeprom (bytes): 4096
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: Yes
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 1.6 to 3.6
• Operating Voltage (vcc): 1.6 to 3.6
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 7
• Output Compare Channels: 22
• Input Capture Channels: 22
• Pwm Channels: 22
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

10. System Clock and Clock options
10.1
10.2
8386A–AVR–07/11
Features
Overview
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The flexible clock system supports a large number of clock sources. It incorporates both accu-
rate internal oscillators, and external crystal oscillators and resonator support. A high frequency
Phase Locked Loop (PLL) and clock prescalers can be used to generate a wide range of clock
frequencies. A calibration feature (DFLL) is available, and can be used for automatic runtime
calibration of the internal oscillators to remove frequency drift over voltage and temperate. An
Oscillator Failure Monitor can be enabled to issue a Non-Maskable Interrupt and switch to inter-
nal oscillator if the external oscillator or PLL fails.
When a reset occur, all clock sources except 32kHz Ultra Low Power oscillator are disabled.
After reset, the device will always start up running from the 2MHz internal oscillator. During nor-
mal operation, the System Clock source and prescalers can be changed from software at any
time.
Figure 10-1 on page 19
not need to be active at a given time. The clocks to the CPU and peripherals can be stopped
using sleep modes and power reduction registers.
Fast start-up time
Safe run-time clock switching
Internal Oscillators:
External clock options
PLL with 20 - 128MHz output frequency
Clock Prescalers with 1 to 2048x division
Fast peripheral clocks running at 2 and 4 times the CPU clock frequency
Automatic Run-Time Calibration of internal oscillators
External oscillator and PLL lock failure detection with optional non maskable interrupt
– 32MHz run-time calibrated and tuneable oscillator
– 2MHz run-time calibrated oscillator
– 32.768kHz calibrated oscillator
– 32kHz Ultra Low Power (ULP) oscillator with 1kHz output
– 0.4 - 16MHz Crystal Oscillator
– 32kHz Crystal Oscillator
– External clock
– Internal and external clock options and 1 to 31x multiplication
– Lock detector
presents the principal clock system in the XMEGA. All of the clocks do
XMEGA A3U
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