How To Read A/D Converter Characteristics Table - NEC V850E/RS1 User Manual

11.8 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
When the resolution is 10 bits, 1LSB is as follows:
1LSB = 1/2
= 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.
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Chapter 11 A/D Converter
= (Maximum value of convertible analog input voltage – Minimum value of convertible
analog input voltage)/100
= (AV – 0)/100
REF0
= AV /100
REF0
10
= 1/1024
Figure 11-19: Overall Error
1 ...... 1 1 ...... 1
Ideal line Ideal line
0 ...... 0 0 ...... 0
0
User's Manual U16702EE3V2UD00
Overall error Overall error
AV
REF0
Analog input Analog input