ATmega88PA Automotive Atmel Corporation, ATmega88PA Automotive Datasheet - Page 147

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

18.8
18.8.1
18.8.2
7701E–AVR–02/11
ADC Conversion Result
Single Ended Conversion
Unipolar Differential Conversion
Figure 18-12. Differential Non-linearity (DNL)
• Quantization Error: Due to the quantization of the input voltage into a finite number of codes,
• Absolute Accuracy: The maximum deviation of an actual (unadjusted) transition compared to
After the conversion is complete (ADIF is high), the conversion result can be found in the ADC
result registers (ADCL, ADCH). The form of the conversion result depends on the type of the
conversion, as there are three types of conversion: single-ended conversion, unipolar differen-
tial conversion and bipolar differential conversion.
For single ended conversion, the result is
where V
Table 18-3 on page 149
0x3FF represents the selected reference voltage minus 1LSB. The result is presented in
one-sided form, from 0x3FF to 0x000.
If differential channels and an unipolar input mode are used, the result is
where V
and V
a range of input voltages (1LSB wide) will code to the same value. Always ±0.5LSB.
an ideal transition for any code. This is the compound effect of offset error, gain error,
differential error, non-linearity, and quantization error. Ideal value: ±0.5LSB.
REF
IN
POS
the selected voltage reference.
is the voltage on the selected input pin and V
is the voltage on the positive input pin, V
Output Code
0x000
0x3FF
and
ADC
Atmel ATtiny24/44/84 [Preliminary]
0
Table 18-4 on page
=
1 LSB
---------------------------------------------------------- -
V
ADC
POS
–
=
V
V
NEG
V
---------------------------- -
REF
IN
V
REF
150). 0x000 represents analog ground, and
1024
1024
NEG
REF
the voltage on the negative input pin,
the selected voltage reference (see
GAIN
V
REF
Input Voltage
147