NEC 78K0/KB1+, Preliminary User'S Manual

Page: 196 / 405

CHAPTER 10 A/D CONVERTER
Preliminary User’s Manual U16846EJ1V0UD
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(4) Zero-scale error
This shows the difference between the actual measurement value of the analog input voltage and the theoretical
value (1/2LSB) when the digital output changes from 0......000 to 0......001.
If the actual measurement value is greater than the theoretical value, it shows the difference between the actual
measurement value of the analog input voltage and the theoretical value (3/2LSB) when the digital output
changes from 0……001 to 0……010.
(5) Full-scale error
This shows the difference between the actual measurement value of the analog input voltage and the theoretical
value (Full-scale
−
3/2LSB) when the digital output changes from 1......110 to 1......111.
(6) Integral linearity error
This shows the degree to which the conversion characteristics deviate from the ideal linear relationship. It
expresses the maximum value of the difference between the actual measurement value and the ideal straight line
when the zero-scale error and full-scale error are 0.
(7) Differential linearity error
While the ideal width of code output is 1LSB, this indicates the difference between the actual measurement value
and the ideal value.
Figure 10-15. Zero-Scale Error Figure 10-16. Full-Scale Error
111
011
010
001
Zero-scale error
Ideal line
000
0 1 2 3 AV
REF
Digital output (Lo
w
er 3 bits)
Analog input (LSB)
111
110
101
000
0 AV
REF
AV
REF
–1 AV
REF
–2 AV
REF
–3
Digital output (Lo
w
er 3 bits)
Analog input (LSB)
Ideal line
Full-scale error
Figure 10-17. Integral Linearity Error Figure 10-18. Differential Linearity Error
0
AV
REF
Digital output
Analog input
Integral linearity
error
Ideal line
1……1
0……0
0
AV
REF
Digital output
Analog input
Differential
linearity error
1……1
0……0
Ideal 1LSB width