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CHAPTER 10 A/D CONVERTER
User’s Manual U15104EJ2V0UD
10.4.2 Input voltage and conversion results
The relationship between the analog input voltage input to the analog input pins (ANI0 to ANI5) and the A/D
conversion result (the value stored in A/D conversion result register 3 (ADCR3) is shown by the following expression.
ADCR3 = INT (
×
256 + 0.5)
or
(ADCR3 – 0.5)
×
≤
V
IN
< (ADCR3 + 0.5)
×
Remark
INT( ):
Function which returns integer parts of value in parentheses.
V
IN
:
Analog input voltage
V
DD
:
V
DD
pin voltage
ADCR3: A/D conversion result register 3 (ADCR3) value
Figure 10-6 shows the relationship between the analog input voltage and the A/D conversion result.
Figure 10-6. Relationship Between Analog Input Voltage and A/D Conversion Result
V
IN
V
DD
V
DD
256
V
DD
256
1
512
1
256
3
512
2
256
5
512
3
256
507
512
254
256
509
512
255
256
511
512
1
255
254
253
3
2
1
0
A/D conversion
results (ADCR3)
Input voltage/V
DD