Datasheet

182
ATmega8A [DATASHEET]
8159E–AVR–02/2013
23. Analog-to-Digital Converter
23.1 Features
• 10-bit Resolution
• 0.5LSB Integral Non-linearity
• ± 2LSB Absolute Accuracy
• 13 - 260µs Conversion Time
• Up to 15kSPS at Maximum Resolution
• 6 Multiplexed Single Ended Input Channels
• 2 Additional Multiplexed Single Ended Input Channels (TQFP and QFN/MLF Package only)
• Optional Left Adjustment for ADC Result Readout
• 0 - V
CC
ADC Input Voltage Range
• Selectable 2.56V ADC Reference Voltage
• Free Running or Single Conversion Mode
• Interrupt on ADC Conversion Complete
• Sleep Mode Noise Canceler
23.2 Overview
The ATmega8A features a 10-bit successive approximation ADC. The ADC is connected to an 8-channel Analog
Multiplexer which allows eight single-ended voltage inputs constructed from the pins of Port C. 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.
The ADC has a separate analog supply voltage pin, AV
CC
. AV
CC
must not differ more than ± 0.3V from V
CC
. See
the paragraph “ADC Noise Canceler” on page 187 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 exter-
nally decoupled at the AREF pin by a capacitor for better noise performance.