at90pwm81-16se ATMEL Corporation, at90pwm81-16se Datasheet - Page 214

• Manufacturer Part Number: at90pwm81-16se
• Description: 8-bit Avr Microcontroller With 8k Bytes In- System Programmable Flash
• Manufacturer: ATMEL Corporation

18.7
214
ADC Conversion Result
AT90PWM81
Figure 18-13. Differential Non-linearity (DNL)
After the conversion is complete (ADIF is high), the conversion result can be found in the ADC Result
Registers (ADCL, ADCH).
For single ended conversion, the result is:
where V
on page 217
selected reference voltage.
If differential channels are used, the result is:
where V
selected gain factor and V
form, from 0x200 (-512d) through 0x1FF (+511d). Note that if the user wants to perform a quick polarity
check of the result, it is sufficient to read the MSB of the result (ADC9 in ADCH). If the bit is one, the
• Quantization Error: Due to the quantization of the input voltage into a finite number of codes, a range
• Absolute Accuracy: The maximum deviation of an actual (unadjusted) transition compared to an ideal
of input voltages (1 LSB wide) will code to the same value. Always ± 0.5 LSB.
transition for any code. This is the compound effect of offset, gain error, differential error, non-
linearity, and quantization error. Ideal value: ± 0.5 LSB.
IN
POS
is the voltage on the selected input pin and V
is the voltage on the positive input pin, V
and
Output Code
Table 18-4 on page
0x000
0x3FF
REF
0
the selected voltage reference. The result is presented in two’s complement
1 LSB
ADC
217). 0x000 represents analog ground, and 0x3FF represents the
=
(
---------------------------------------------------------------------- -
V
ADC
POS
NEG
–
=
REF
V
V
------------------------ -
the voltage on the negative input pin, GAIN the
NEG
IN
V
the selected voltage reference (see
V
REF
REF
⋅
) GAIN 512
1023
⋅
V
⋅
REF
Input Voltage
7734M–AVR–03/10
Table 18-3