MITSUBISHI MICROCOMPUTERS
M37271MF-XXXSP
M37271EF-XXXSP, M37271EFSP
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER with CLOSED CAPTION DECODER
and ON-SCREEN DISPLAY CONTROLLER
28
[LSB]
[LSB]
(8) Definition of A-D Conversion Accuracy
The definition of A-D conversion accuracy is described below.
1Relative accuracy
· Zero transition error (V0T)
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 VREF.
· Non-linearity error
The deviation of the actual A-D conversion characteristics, from the
ideal A-D conversion characteristics between V0 and V254.
(V0 –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 VREF.
2Absolute accuracy
· Absolute accuracy error
The deviation of the actual A-D conversion characteristics, from the
ideal A-D conversion characteristics between 0 and VREF.
Vn – (1LSB ✕ n + V0)
1LSB
[LSB]Differential non-linearity error =
(Vn+1 – Vn) – 1LSB
1LSB
Absolute accuracy error =
1LSBA 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. 21. 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 VREF.
Vn – 1LSBA ✕ (n+1/2)
1LSBA
Output
data
0
Analog input
voltage (V)
V
0
V
n
V
n+1
V
254
V
REF
n
n+1
254
255
Zero transition error (V
0T
)
Differential non-
linearity error
LSB
A
Actual A-D
conversion
characteristics
1
2
3
2
V
1
1LSB
A
Ideal A-D conversion characteristics
between V
0
and V
254
LSB
A
1LSB
Absolute accuracy
Non-linearity error
Full-scale transition error
(V
FST
)
1LSB
(145 stránky)
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