atxmega256a3b-mu ATMEL Corporation, atxmega256a3b-mu Datasheet - Page 42

• Manufacturer Part Number: atxmega256a3b-mu
• Description: 8/16-bit Xmega A3b Microcontroller
• Manufacturer: ATMEL Corporation

25. ADC - 12-bit Analog to Digital Converter
25.1
25.2
8116C–AVR–02/09
Features
Overview
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XMEGA A3B devices have two Analog to Digital Converters (ADC), see
The two ADC modules can be operated simultaneously, individually or synchronized.
The ADC converts analog voltages to digital values. The ADC has 12-bit resolution and is capa-
ble of converting up to 2 million samples per second. 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 pipeline ADC. A pipeline ADC consists of several consecutive stages, where each
stage convert one part of the result. The pipeline design enables high sample rate at low clock
speeds, and remove limitations on samples speed versus propagation delay. This also means
that a new analog voltage can be sampled and a new ADC measurement started while other
ADC measurements are ongoing.
ADC measurements can either be started by application software or an incoming event from
another peripheral in the device. Four different result registers with individual input selection
(MUX selection) are provided to make it easier for the application to keep track of the data. Each
result register and MUX selection pair is referred to as an ADC Channel. It is possible to use
DMA to move ADC results directly to memory or peripherals when conversions are done.
Both internal and external analog reference voltages can be used. An accurate internal 1.0V
reference is available.
An integrated temperature sensor is available and the output from this can be measured with the
ADC. The output from the DAC, VCC/10 and the Bandgap voltage can also be measured by the
ADC.
Two ADCs with 12-bit resolution
2 Msps sample rate for each ADC
Signed and Unsigned conversions
4 result registers with individual input channel control for each ADC
8 single ended inputs for each ADC
8x4 differential inputs for each ADC
4 internal inputs:
Software selectable gain of 2, 4, 8, 16, 32 or 64
Software selectable resolution of 8- or 12-bit.
Internal or External Reference selection
Event triggered conversion for accurate timing
DMA transfer of conversion results
Interrupt/Event on compare result
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Integrated Temperature Sensor
DAC Output
VCC voltage divided by 10
Bandgap voltage
XMEGA A3B
Figure 25-1 on page
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