Datasheet

V850ES/JG3 CHAPTER 13 A/D CONVERTER
R01UH0015EJ0300 Rev.3.00 Page 438 of 870
Sep 30, 2010
13.7 How to Read A/D Converter Characteristics Table
This section describes the terms related to the A/D converter.
(1) Resolution
The minimum analog input voltage that can be recognized, i.e., the ratio of an analog input voltage to 1 bit of digital
output is called 1 LSB (least significant bit). The ratio of 1 LSB to the full scale is expressed as %FSR (full-scale
range). %FSR is the ratio of a range of convertible analog input voltages expressed as a percentage, and can be
expressed as follows, independently of the resolution.
1%FSR = (Maximum value of convertible analog input voltage – Minimum value of convertible analog
input voltage)/100
= (AV
REF0 − 0)/100
= AVREF0/100
When the resolution is 10 bits, 1 LSB is as follows:
1 LSB = 1/2
10
= 1/1,024
= 0.098%FSR
The accuracy is determined by the overall error, independently of the resolution.
(2) Overall error
This is the maximum value of the difference between an actually measured value and a theoretical value.
It is a total of zero-scale error, full-scale error, linearity error, and a combination of these errors.
The overall error in the characteristics table does not include the quantization error.
Figure 13-16. Overall Error
Ideal line
Overall error
1
......
1
0
......
0
0AV
REF0
Analog input
Digital output