M37280MF Datasheet, PDF (53/178 Pages) Mitsubishi Electric Semiconductor – SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER with CLOSED CAPTION DECODER and ON-SCREEN DISPLAY CONTROLLER

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MITSUBISHI MICROCOMPUTERS
M37280MF–XXXSP, M37280MK–XXXSP
M37280EKSP
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER with CLOSED CAPTION DECODER
and ON-SCREEN DISPLAY CONTROLLER
12.8.8 Definition of A-D Conversion Accuracy
The definition of A-D conversion accuracy is described below (refer
to Figure 12.8.4).
(1) 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.
(VREF – 3/2 ! VREF/256) – V254
VFST =
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]
• EDifferential 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.
(Vn+1 – Vn) – 1LSB
Differential non-linearity error =
[LSB]
1LSB
(2) Absolute Accuracy
• EAbsolute 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
12.8.4) :
1LSB with respect to relative accuracy =
V254 – V0
254
[V]
1LSBA with respect to absolute accuracy =
VREF
256
[V]
Output code
0916
0816
0716
0616
0516
0416
Absolute accuracy
+ 2LSB
Ideal A-D conversion
characteristics
Limitless resolution A-D
conversion characteristics
0316
0216
– 2LSB
0116
0016
0
20 40
60 80 100 120 140 160 180 200 220
Analog input voltage (mV)
Fig. 12.8.4 Definition of A-D Conversion Accuracy
Rev. 1.0
53