Datasheet

Figure 27-1. Analog to Digital Converter Block Schematic Operation
ADC CONVERSION
COMPLETE IRQ
8-BIT DATA BUS
15 0
ADC MULTIPLEXER
SELECT (ADMUX)
ADC CTRL. & STATUS
REGISTER (ADCSRA)
ADC DATA REGISTER
(ADCH/ADCL)
MUX2
ADIE
ADFR
ADSC
ADEN
ADIF
ADIF
MUX1
MUX0
ADPS0
ADPS1
ADPS2
MUX3
CONVERSION LOGIC
10-BIT DAC
+
-
SAMPLE & HOLD
COMPARATOR
INTERNAL 1.1V
REFERENCE
MUX DECODER
AVCC
ADC7
ADC6
ADC5
ADC4
ADC3
ADC2
ADC1
ADC0
REFS0
REFS1
ADLAR
CHANNEL SELECTION
ADC[9:0]
ADC MULTIPLEXER
OUTPUT
AREF
BANDGAP
REFERENCE
PRESCALER
GND
INPUT
MUX
TEMPERATURE
SENSOR
The ADC converts an analog input voltage to a 10-bit digital value through successive approximation.
The minimum value represents GND and the maximum value represents the voltage on the AREF pin
minus 1LSB. Optionally, AV
CC
or an internal 2.56V reference voltage may be connected 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.
The analog input channel is selected by writing to the MUX bits in ADMUX. Any of the ADC input pins, as
well as GND and a fixed bandgap voltage reference, can be selected as single ended inputs to the ADC.
The ADC is enabled by setting the ADC Enable bit, ADEN in ADCSRA. Voltage reference and input
channel selections will not go into effect until ADEN is set. The ADC does not consume power when
ADEN is cleared, so it is recommended to switch off the ADC before entering power saving sleep modes.
AVR 8-Bit Microcontroller
ADC - Analog to Digital Converter
© 2017 Microchip Technology Inc.
Datasheet Complete
40001974A-page 254