M37270MF Datasheet, PDF (25/94 Pages) Mitsubishi Electric Semiconductor – SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER with CLOSED CAPTION DECODER and ON-SCREEN DISPLAY CONTROLLER

MITSUBISHI MICROCOMPUTERS
M37270MF-XXXSP
M37270EF-XXXSP, M37270EFSP
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER with CLOSED CAPTION DECODER
and ON-SCREEN DISPLAY CONTROLLER
(8) Definition of A-D Conversion Accuracy
The definition of A-D conversion accuracy is described below.
Relative 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.
V0T=
(V0 – 1/2 ! VREF/256)
1LSB
[ LSB]
• 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.
VFST =
(VREF – 3/2 ! VREF/256) – V254
1LSB
[ LSB]
• Non-linearity error
The deviation of the actual A-D conversion characteristics, from the
ideal A-D conversion characteristics between V0 and V254.
Non-linearity error =
Vn – (1LSB! n + V0)
1LSB
[ 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.
Differential non-linearity error =
(Vn+1 – Vn) – 1LSB
[ LSB]
1LSB
Absolute 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 – 1LSBA ! (n + 1/2)
Absolute accuracy error =
1LSBA
[LSB]
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
1LSB with respect to relative accuracy =
[V]
254
VREF
1LSBA with respect to absolute accuracy =
256
[V]
Output
data
255
254
n+1
n
Full-scale transition error
(VFST)
Differential non-
linearity error
1LSB
3
2
LSBA
Actual A-D
conversion
characteristics
Non-linearity error
Absolute accuracy
1LSB A
1
2 ^LSBA
Ideal A-D conversion characteristics
between V0 and V254
1LSB
0
V0 V1
Vn Vn+1
Zero transition error (V0T)
Fig. 18. Definition of A-D conversion precision
V254
VR EF
Analog input
voltage ( V )
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