386
8331B–AVR–03/12
Atmel AVR XMEGA AU
29. DAC – Digital to Analog Converter
29.1
Features
•
12-bit resolution
•
Two independent, continuous-drive output channels
•
Up to one million samples per second conversion rate per DAC channel
•
Built-in calibration that removes:
– Offset error
– Gain error
•
Multiple conversion trigger sources
– On new available data
– Events from the event system
•
High drive capabilities and support for
– Resistive loads
– Capacitive loads
– Combined resistive and capacitive loads
•
Internal and external reference options
•
DAC output available as input to analog comparator and ADC
•
Low-power mode, with reduced drive strength
•
Optional DMA transfer of data
29.2
Overview
The digital-to-analog converter (DAC) converts digital values to voltages. The DAC has two
channels, each with12-bit resolution, and is capable of converting up to one million samples per
second (MSPS) on each channel. The built-in calibration system can remove offset and gain
error when loaded with calibration values from software.
illustrates the basic functionality of the DAC. Not all functions are shown.
Figure 29-1.
DAC overview.
CTRLA
CH1DATA
CH0DATA
Trigger
Trigger
Internal Output enable
Enable
Internal 1.00V
AREFA
AREFB
Reference
voltage
AVCC
Output
Driver
Output
Driver
D
A
T
A
Int.
driver
D
A
T
A
CTRLB
DMA req
(Data Empty)
DMA req
(Data Empty)
Select
12
12
Select
Enable
To
AC/ADC
