MITSUBISHI MICROCOMPUTERS
M37270MF-XXXSP
M37270EF-XXXSP, M37270EFSP
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER with CLOSED CAPTION DECODER
and ON-SCREEN DISPLAY CONTROLLER
25
[LSB]
[LSB]
(8) Definition of A-D Conversion Accuracy
The definition of A-D conversion accuracy is described below.
Relative accuracy
• Zero transition error (V
0T)
The deviation of the input voltage at which A-D conversion output
data changes from “0” to “1,” from the corresponding ideal A-D
conversion characteristics between 0 and V
REF.
• Non-linearity error
The deviation of the actual A-D conversion characteristics, from the
ideal A-D conversion characteristics between V
0 and V254.
(V
0 – 1/2✕ VREF/256)
1LSB
V0T=
(VREF – 3/2✕VREF/256) – V254
1LSB
VFST =
Non-linearity error =
[LSB]
[LSB]
• Differential non-linearity error
The deviation of the input voltage required to change output data
by “1,” from the corresponding ideal A-D conversion characteris-
tics between 0 and V
REF.
Absolute accuracy
• Absolute accuracy error
The deviation of the actual A-D conversion characteristics, from the
ideal A-D conversion characteristics between 0 and V
REF.
Vn – (1LSB✕ n+V0)
1LSB
[LSB]Differential non-linearity error=
(Vn+1 –Vn)– 1LSB
1LSB
Absolute accuracy error =
1LSB
A with respect to absolute accuracy =
1LSB with respect to relative accuracy =
Note: The analog input voltage “Vn” at which A-D conversion output
data changes from “n” to “n + 1” (n ; 0 to 254) is as follows
(refer to Figure 18).
V254 –V0
254
VREF
256
[V]
[V]
Fig. 18. Definition of A-D conversion precision
• Full-scale transition error (VFST)
The deviation of the input voltage at which A-D conversion output
data changes from “255” to “254,” from the corresponding ideal A-
D conversion characteristics between 0 and V
REF.
Output
data
0
Analog input
voltage (V)
V0 Vn Vn+1 V254 VREF
n
n+1
254
255
Zero transition error (V0T)
Differential non-
linearity error
LSBA
Actual A-D
conversion
characteristics
1
2
3
2
V1
1LSB A
Ideal A-D conversion characteristics
between V
0 and V254
LSB
A
1LSB
Absolute accuracy
Non-linearity error
Full-scale transition error
(V
FST)
1LSB
Vn – 1LSBA ✕ (n + 1/2)
1LSBA
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