Datasheet

Table Of Contents
26. ADC - Analog to Digital Converter
26.1. Features
10-bit Resolution
0.5 LSB Integral Non-Linearity
±2 LSB Absolute Accuracy
13 - 260μs Conversion Time
Up to 15ksps at Maximum Resolution
8 Multiplexed Single Ended Input Channels
7 Differential Input Channels
2 Differential Input Channels with Optional Gain of 10x and 200x
Optional Left Adjustment for ADC Result Readout
0 - V
CC
ADC Input Voltage Range
2.7 - V
CC
Differential ADC Voltage Range
Selectable 2.56V ADC Reference Voltage
Free Running or Single Conversion Mode
ADC Start Conversion by Auto Triggering on Interrupt Sources
Interrupt on ADC Conversion Complete
Sleep Mode Noise Canceler
26.2. Overview
The ATmega32A features a 10-bit successive approximation ADC. The ADC is connected to an 8-
channel Analog Multiplexer which allows 8 single-ended voltage inputs constructed from the pins of Port
A. The single-ended voltage inputs refer to 0V (GND).
The device also supports 16 differential voltage input combinations. Two of the differential inputs (ADC1,
ADC0 and ADC3, ADC2) are equipped with a programmable gain stage, providing amplification steps of
0dB (1x), 20dB (10x), or 46dB (200x) on the differential input voltage before the A/D conversion. Seven
differential analog input channels share a common negative terminal (ADC1), while any other ADC input
can be selected as the positive input terminal. If 1x or 10x gain is used, 8-bit resolution can be expected.
If 200x gain is used, 7-bit resolution can be expected.
The ADC contains a Sample and Hold circuit which ensures that the input voltage to the ADC is held at a
constant level during conversion. A block diagram of the ADC is shown below.
The ADC has a separate analog supply voltage pin, AV
CC
. AV
CC
must not differ more than ±0.3V from
V
CC
. See section ADC Noise Canceler on how to connect this pin.
Internal reference voltages of nominally 2.56V or AV
CC
are provided On-chip. The voltage reference may
be externally decoupled at the AREF pin by a capacitor for better noise performance.
Atmel ATmega32A [DATASHEET]
Atmel-8155I-ATmega32A_Datasheet_Complete-08/2016
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