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
• Differential non-linearity error
The definition of A-D conversion accuracy is described below.
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.
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.
(Vn+1 – Vn)– 1LSB
Differential non-linearity error=
[LSB]
1LSB
Absolute accuracy
• Absolute accuracy error
(V0 – 1/2 ✕VREF/256)
The deviation of the actual A-D conversion characteristics, from the
ideal A-D conversion characteristics between 0 and VREF.
V0T=
[LSB]
1LSB
• 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)
Absolute accuracy error =
[LSB]
1LSBA
(VREF – 3/2✕VREF/256) – V254
VFST =
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).
[LSB]
1LSB
• Non-linearity error
The deviation of the actual A-D conversion characteristics, from the
ideal A-D conversion characteristics between V0 and V254.
V254 – V0
1LSB with respect to relative accuracy =
1LSBA with respect to absolute accuracy =
[V]
[V]
254
Vn – (1LSB✕n +V0)
VREF
256
Non-linearity error =
[LSB]
1LSB
Output
data
255
Full-scale transition error
(VFST)
254
3
Differential non-
linearity error
LSBA
2
1LSB
n+1
n
Actual A-D
Non-linearity error
conversion
Absolute accuracy
characteristics
1LSB A
1
2
Ideal A-D conversion characteristics
between V0 and V254
A
LSB
1LSB
Analog input
voltage (V)
0
V0 V1
Vn Vn+1
V254
VREF
Zero transition error (V0T)
Fig. 18. Definition of A-D conversion precision
25
RENESAS [ RENESAS TECHNOLOGY CORP ]
