Datasheet

28. ADC - Analog to Digital Converter
28.1. Features
• 10-bit Resolution
• 0.75 LSB Integral Non-Linearity
• ±1.5 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
28.2. Overview
The ATmega64A 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
F. 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 page 318 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 ATmega64A [DATASHEET]
Atmel-8160E-ATmega64A_Datasheet_Complete-09/2015
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