UPD78F0138 NEC, UPD78F0138 Datasheet - Page 261

• Manufacturer Part Number: UPD78F0138
• Description: (UPD78xxxx) 8-Bit Single-Chip Microcontrollers
• Manufacturer: NEC

12.4.2 Input voltage and conversion results
A/D conversion result (stored in the A/D conversion result register (ADCR)) is shown by the following expression.
The relationship between the analog input voltage input to the analog input pins (ANI0 to ANI7) and the theoretical
or
where, INT( ):
Figure 12-9 shows the relationship between the analog input voltage and the A/D conversion result.
SAR = INT (
ADCR = SAR × 64
(ADCR − 0.5) ×
A/D conversion result
V
AV
ADCR: A/D conversion result register (ADCR) value
SAR:
AIN
REF
Figure 12-9. Relationship Between Analog Input Voltage and A/D Conversion Result
:
:
AV
Function which returns integer part of value in parentheses
Analog input voltage
AV
Successive approximation register
V
AIN
(ADCR)
REF
AV
1024
REF
REF
× 1024 + 0.5)
pin voltage
≤ V
AIN
< (ADCR + 0.5) ×
1023
1022
1021
SAR
3
2
1
0
CHAPTER 12 A/D CONVERTER
2048
1
User’s Manual U16228EJ2V0UD
1024
1
2048
AV
1024
3
REF
1024
2
2048
5
Input voltage/AV
1024
3
2043
2048
REF
1022
1024
2045
2048
1023
1024
2047
2048
ADCR
1
FFC0H
FF80H
FF40H
00C0H
0080H
0040H
0000H
261