How To Read A/D Converter Characteristics Table - NEC V850E/Dx3 Preliminary User's Manual

32-bit single-chip microcontroller
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Chapter 20
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20.6 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, 1 LSB is as follows:
1 LSB
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 20-10
Overall error
Preliminary User's Manual U17566EE1V2UM00
=
(Maximum value of convertible analog input voltage –
Minimum value of convertible analog input voltage)/100
=
(AV
– 0)/100
REF
=
AV
/100
REF
10
=
1/2
= 1/1,024
=
0.098%FSR
1 ...... 1
Ideal line
0 ...... 0
0
Analog input
A/D Converter (ADC)
Overall error
AV
REF

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