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8.4 Absolute accuracy and differential non-linearity error
8.4.1 Absolute accuracy
The absolute accuracy is the difference expressed in the LSB between the actual A-D conversion result
and the output code of an A-D converter with ideal characteristics. The analog input voltage when measuring
the accuracy is assumed to be the mid point of the input voltage width that outputs the same output code
from an A-D converter with ideal characteristics. For example, in the case of the 10-bit mode, when
V
=5.12 V, 1 LSB width is 5 mV, and 0 mV, 5 mV, 10 mV, 15 mV, 20 mV, ... are selected as the analog
REF
input voltages.
The absolute accuracy = ±3 LSB indicates that when the analog input voltage is 25 mV, the output code
expected from an ideal A-D conversion characteristics is "005
between "002
" to "008
16
The absolute accuracy includes the zero error and the full-scale error.
The absolute accuracy degrades when V
AV
is "3FF
."
CC
16
Output code
(A-D conversion result)
00B
16
00A
16
009
16
008
16
007
16
006
16
005
16
004
16
003
16
002
16
001
16
000
16
Fig. 8.4.1 Absolute accuracy of A-D converter in 10-bit mode
8.4 Absolute accuracy and differential non-linearity error
."
16
REF
0
5
10
15
Analog input voltage (mV)
7751 Group User's Manual
," but the actual A-D conversion result is
16
is lowered. The output code for analog input voltages V
+3 LSB
–3 LSB
20
25
30
35
A-D CONVERTER
Ideal A-D conversion
characteristics
40
45
50
55
to
REF
8–13
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