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7810C–AVR–10/12
Atmel ATmega328P [Preliminary]
23. Analog-to-Digital Converter
23.1
Features
10-bit Resolution
0.5 LSB Integral Non-linearity
± 2 LSB Absolute Accuracy
65 - 260 s Conversion Time
Up to 15 kSPS
6 Multiplexed Single Ended Input Channels
2 Additional Multiplexed Single Ended Input Channels
Temperature Sensor Input Channel
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
Interrupt on ADC Conversion Complete
Sleep Mode Noise Canceler
23.2
Overview
The ATmega328P 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 A. 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 23-1The ADC has a separate analog supply voltage pin, AV
CC. AVCC must not differ more than ±
0.3V from V
pin.
Internal reference voltages of nominally 1.1V or AV
CC are provided On-chip. The voltage refer-
ence may be externally decoupled at the AREF pin by a capacitor for better noise performance.
be disabled by writing a logical zero to enable the ADC.
The ADC converts an analog input voltage to a 10-bit digital value through successive approxi-
mation. The minimum value represents GND and the maximum value represents the voltage on
the AREF pin minus 1 LSB. Optionally, AV
CC or an internal 1.1V reference voltage may be con-
nected to the AREF pin by writing to the REFSn bits in the ADMUX Register. The internal
voltage reference may thus be decoupled by an external capacitor at the AREF pin to improve
noise immunity.