ATxmega256A3 Atmel Corporation, ATxmega256A3 Datasheet - Page 318

• Manufacturer Part Number: ATxmega256A3
• Manufacturer: Atmel Corporation

Specifications of ATxmega256A3

• 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 Speed: No
• Usb Interface: No
• 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

26.3
26.4
26.5
8077H–AVR–12/09
Starting a conversion
Output channels
DAC Output model
Figure 26-1. DAC overview
Conversions are either done when data is written to the data registers, or timed by an incoming
event.
If auto trigger mode is not selected, a new conversion is automatically started when there is a
new value in the DAC data register. When auto trigger mode is selected, the new conversion will
be started on an incoming event from the selected event channel if there is new data in the data
register which has not been converted.
Both application software and the DMA controller may write to the data registers.
The output from the DAC can either be continuous to one pin (Channel 0), or fed into two differ-
ent pins using a sample and hold circuitry (S/H). With S/H these two outputs can act
independently and create two different analog signals, different in both voltage and frequency.
The two S/H outputs have individual data and conversion control registers. The DAC output may
be used as input to other peripherals in XMEGA, such as the Analog Comparator or the Analog
to Digital Converter. It is the output directly from the DAC, not the S/H outputs, that is available
for these peripherals.
Each DAC output channel has a driver buffer with feedback ensures that the voltage on the DAC
output pin is equal to the DACs internal voltage until the DAC output reaches its saturation volt-
age.
DAC characteristics in the device data sheet.
CH0DATA
CH1DATA
Figure 26-2 on page 319
12
12
Int. 1.00 V
AREFA
AREFB
AVCC
12
shows the DAC output model, for details on R
REFSEL
TRIG
CTRL
DAC
DAC
ENABLE
Control and Driver
ADC
AC
Output
XMEGA A
channel
, refer to the
DAC CH0
DAC CH1
318