ATxmega256A3B Atmel Corporation, ATxmega256A3B Datasheet - Page 77

• Manufacturer Part Number: ATxmega256A3B
• Manufacturer: Atmel Corporation

Specifications of ATxmega256A3B

• 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: 47
• Ext Interrupts: 49
• Usb Speed: No
• Usb Interface: No
• Spi: 8
• Twi (i2c): 2
• Uart: 6
• 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

Figure 7-1.
7.3
7.3.1
7.3.2
8077H–AVR–12/09
Clock Distribution
System Clock - clk
CPU Clock - clk
Brown-out
Detection
The Clock system, clock sources and clock distribution
Real Time
Counter
Figure 7-1 on page 77
The System Clock is the output from the main system clock selection. This is fed into the pres-
calers that are used to generate all internal clocks except the Asynchronous Clock.
The CPU Clock is routed to the CPU and Non-Volatile Memory. Halting the CPU Clock inhibits
the CPU from executing instructions.
Watchdog
CPU
Int. ULP
32 kHz
Timer
SYS
clk
rtc
32.768 kHz
Int. Osc.
Peripherals
clk
PER4
clk
PER2
clk
presents the principal clock distribution in the XMEGA.
PER
Int. Osc.
2 MHz
RAM
System Clock
System Clock Multiplexer
Prescalers
clk
SYS
Int. Osc.
32 MHz
PLL
32 kHz
XTAL
AVR CPU
clk
CPU
0.4-16 Mhz
XTAL
Non-Volatile
Memory
XMEGA A
External
Clock
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