M34512M2 Datasheet, PDF (36/80 Pages) Mitsubishi Electric Semiconductor – SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

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(15) Definition of A-D converter accuracy
The A-D conversion accuracy is defined below (refer to Figure 29).
• Relative accuracy
ΠZero transition voltage (V0T)
This means an analog input voltage when the actual A-D con-
version output data changes from “0” to “1.”
 Full-scale transition voltage (VFST)
This means an analog input voltage when the actual A-D con-
version output data changes from “1023” to ”1022.”
Ž Linearity error
This means a deviation from the line between V0T and VFST of
a converted value between V0T and VFST.
 Differential non-linearity error
This means a deviation from the input potential difference re-
quired to change a converter value between V0T and VFST by 1
LSB at the relative accuracy.
• Absolute accuracy
This means a deviation from the ideal characteristics between 0
to VDD of actual A-D conversion characteristics.
MITSUBISHI MICROCOMPUTERS
4512 Group
SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER
Output data
1023
Full-scale transition voltage (VFST)
1022
Differential non-linearity error = ^b–a
a
[LSB]
Linearity error =
c
a
[LSB]
b
a
n+1
n
Actual A-D conversion
characteristics
c
a: 1LSB by relative accuracy
b: Vn+1–Vn
c: Difference between ideal Vn
and actual Vn
Ideal line of A-D conversion
between V0–V1022
1
0
V0 V1
Zero transition voltage (V0T)
Fig. 29 Definition of A-D conversion accuracy
Vn Vn+1
V1022
VDD
Analog voltage
Vn: Analog input voltage when the output data changes from “n” to “n+1” (n = 0 to 1022)
• 1LSB at relative accuracy → ^{VFST–V0T} (V)
1022
VDD
• 1LSB at absolute accuracy →
(V)
1024
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