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CHAPTER 12 10-BIT A/D CONVERTER (
µ
PD780034AS SUBSERIES)
Preliminary User’s Manual U16035EJ1V0UM
111
011
010
001
Zero scale offset
Ideal line
000
0
1
2
3
AV
DD
Digital output (lo
w
er 3 bits)
Analog input (LSB)
111
110
101
000
0
AV
DD
AV
DD
–1
AV
DD
–2
AV
DD
–3
Digital output (lo
w
er 3 bits)
Analog input (LSB)
Ideal line
Full scale offset
0
AV
DD
Digital output
Analog input
Integral
linearity
error
Ideal line
1……1
0……0
0
AV
DD
Digital output
1......1
0......0
Ideal width of 1LSB
Differential
linearity error
Analog input
(4) Zero scale offset
This shows the difference between the actual measured 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 measured value is
greater than the theoretical value, it shows the difference between the actual measured 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 offset
This shows the difference between the actual measured 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 measured value and the ideal straight line
when the zero scale offset and full scale offset are 0.
(7) Differential linearity error
Although the ideal output width for a given code is 1LSB, this value shows the difference between the actual
measured value and the ideal value of the width when outputting a particular code.
Figure 12-11. Zero Scale Offset
Figure 12-12. Full Scale Offset
Figure 12-13. Integral Linearity Error
Figure 12-14. Differential Linearity Error