Input Voltage And Conversion Results - NEC mPD780344 Series User Manual

CHAPTER 13 10-BIT A/D CONVERTER ( µ PD780354, 780354Y SUBSERIES)

13.4.2 Input voltage and conversion results

The relationship between the analog voltage input to the analog input pins (ANI0 to ANI7) and the logical A/D
conversion result (stored in A/D conversion result register 0 (ADCR0)) is shown by the following expression.
V
IN
ADCR0 = INT (
AV
DD
or
AV
(ADCR0 – 0.5) ×
1,024
where, INT( ): Function which returns integer part of value in parentheses
V : Analog input voltage
AIN
AV : AV
DD DD
ADCR0: A/D conversion result register 0 (ADCR0) value
Figure 13-6 shows the relationship between the analog input voltage and the A/D conversion result.
Figure 13-6. Relationship Between Analog Input Voltage and A/D Conversion Result
A/D conversion result
(ADCR0)
252
× 1,024 + 0.5)
DD
≤ V < (ADCR0 + 0.5) ×
AIN
pin voltage
1,023
1,022
1,021
3
2
1
0
1 1 3
2,048 1,024 2,048
User's Manual U15798EJ2V0UD
AV
DD
1,024
2 5 3 2,043 1,022
1,024 2,048 1,024 2,048 1,024
Input voltage/AV
DD
2,045 1,023 2,047 1
2,048 1,024 2,048