ATmega88PA Automotive Atmel Corporation, ATmega88PA Automotive Datasheet - Page 138

• Manufacturer Part Number: ATmega88PA Automotive
• Manufacturer: Atmel Corporation

18.3
138
ADC Operation
Atmel ATtiny24/44/84 [Preliminary]
Figure 18-1. Analog-to-Digital Converter Block Schematic
The ADC converts an analog input voltage to a 10-bit digital value through successive approx-
imation. The minimum value represents GND, and the maximum value represents the
reference voltage. The voltage reference for the ADC may be selected by writing to the
REFS1..0 bits in the ADMUX register. The VCC supply, the AREF pin or an internal 1.1V volt-
age reference may be selected as the ADC voltage reference.
The analog input channel and differential gain are selected by writing to the MUX5..0 bits in
the ADMUX register. Any of the eight ADC input pins ADC7..0 can be selected as sin-
gle-ended inputs to the ADC. For differential measurements, all adjacent analog inputs can be
selected as an input pair. Every input can also be measured with ADC3. These pairs of differ-
ential inputs are measured by the ADC through the differential gain amplifier.
ADC7
ADC6
ADC5
ADC4
ADC3
ADC2
ADC1
ADC0
AREF
V
CC
TEMPERATURE
REFERENCE
INTERNAL
8-BIT DATA BUS
AGND
ADC CTRL. & STATUS B
SENSOR
REGISTER (ADCSRB)
1.1V
ADC8
INPUT
INPUT
NEG.
POS.
MUX
MUX
ADTS2...ADTS0
ADC MULTIPLEXER
SELECT (ADMUX)
MUX DECODER
+
-
GAIN
AMPLIFIER
SINGLE ENDED / DIFFERENTIAL SELECTION
10-BIT DAC
ADC CTRL. & STATUS A
REGISTER (ADCSRA)
ADC CONVERSION
COMPLETE IRQ
PRESCALER
CONVERSION LOGIC
INTERRUPT
TRIGGER
SELECT
FLAGS
SAMPLE & HOLD
COMPARATOR
15
+
-
ADC DATA REGISTER
(ADCH/ADCL)
ADC MULTIPLEXER
OUTPUT
7701E–AVR–02/11
0