XMEGA A4U [DATASHEET]
Atmel-8387G-AVR-ATxmega16A4U-34A4U-64A4U-128A4U-Datasheet_03/2014
48
28.
ADC – 12-bit Analog to Digital Converter
28.1
Features
One Analog to Digital Converter (ADC)
12-bit resolution
Up to two million samples per second
Two inputs can be sampled simultaneously using ADC and 1x gain stage
Four inputs can be sampled within 1.5s
Down to 2.5s conversion time with 8-bit resolution
Down to 3.5s conversion time with 12-bit resolution
Differential and single-ended input
Up to 12 single-ended inputs
12x4 differential inputs without gain
8x4 differential inputs with gain
Built-in differential gain stage
1/2
x, 1x, 2x, 4x, 8x, 16x, 32x, and 64x gain options
Single, continuous and scan conversion options
Four internal inputs
Internal temperature sensor
DAC output
VCC voltage divided by 10
1.1V bandgap voltage
Four conversion channels with individual input control and result registers
Enable four parallel configurations and results
Internal and external reference options
Compare function for accurate monitoring of user defined thresholds
Optional event triggered conversion for accurate timing
Optional DMA transfer of conversion results
Optional interrupt/event on compare result
28.2
Overview
The ADC converts analog signals to digital values. The ADC has 12-bit resolution and is capable of converting up to
two million samples per second (msps). The input selection is flexible, and both single-ended and differential
measurements can be done. For differential measurements, an optional gain stage is available to increase the
dynamic range. In addition, several internal signal inputs are available. The ADC can provide both signed and
unsigned results.
This is a pipelined ADC that consists of several consecutive stages. The pipelined design allows a high sample rate at
a low system clock frequency. It also means that a new input can be sampled and a new ADC conversion started
while other ADC conversions are still ongoing. This removes dependencies between sample rate and propagation
delay.
The ADC has four conversion channels (0-3) with individual input selection, result registers, and conversion start
applications with high data throughput or for multiple modules using the ADC independently. It is possible to use DMA
to move ADC results directly to memory or peripherals when conversions are done.
Both internal and external reference voltages can be used. An integrated temperature sensor is available for use with
the ADC. The output from the DAC, VCC/10 and the bandgap voltage can also be measured by the ADC.
The ADC has a compare function for accurate monitoring of user defined thresholds with minimum software
intervention required.