Datasheet

219
8284D–AVR–6/11
ATmega169A/PA/329A/PA/3290A/PA/649A/P/6490A/P
When this bit is wr itten logic one, the digital inp ut buffer on th e AIN1/0 p in is disa bled. The corr espondin g PIN Regi ster bit wil l always read as zero when this bit i s set. When an analog sign al is applied to the AIN1/0 pi n and the digi tal input from t his pin is not needed, this bit should be written lo gic one t o reduce pow er consump tion in the digital input buffer.
23. Analog to Digital Converter
23.1 Features
• 10-bit Resolution
• 0.5LSB Integral Non-linearity
• ± 2LSB Absolute Accuracy
• 13µs - 260µs Conversion Time (50kHz to 1MHz ADC clock)
• Up to 15kSPS at Maximum Resolution (200kHz ADC clock)
• Eight Multiplexed Single Ended Input Channels
• Optional Left Adjustment for ADC Result Readout
• 0 - V
CC
ADC Input Voltage Range
• Selectable 1.1V 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
23.2 Overview
The ATmega169A/169PA/329A/329PA/3290A/3290PA/649A/649P/6490A/6490P features a
10-bit successive approximation ADC. The ADC is connected to an 8-channel Analog Multi-
plexer which allows eight single-ended voltage inputs constructed from the pins of Port F. The
single-ended voltage inputs refer to 0V (GND).
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 in Figure 23-1
on page 220.
The ADC has a separate analog supply voltage pin, AVCC. AV
CC
must not differ more than
± 0.3V from V
CC
. See the paragraph ”ADC Noise Canceler” on page 226 on how to connect this
pin.
Internal reference voltages of nominally 1.1V or AVCC are provided On-chip. The voltage refer-
ence may be externally decoupled at the AREF pin by a capacitor for better noise performance.
The PRADC, in ”PRR – Power Reduction Register” on page 46 must be written to zero to enable
the ADC module.