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4502 Datasheet, PDF (35/116 Pages) Renesas Technology Corp – SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER | |||
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4502 Group
(15) Definition of A/D converter accuracy
The A/D conversion accuracy is defined below (refer to Figure 32).
⢠Relative accuracy
â Zero transition voltage (V0T)
This means an analog input voltage when the actual A/D con-
version output data changes from â0â to â1.â
â Full-scale transition voltage (VFST)
This means an analog input voltage when the actual A/D con-
version output data changes from â1023â to â1022.â
â Linearity error
This means a deviation from the line between V0T and VFST of
a converted value between V0T and VFST.
â Differential non-linearity error
This means a deviation from the input potential difference re-
quired to change a converter value between V0T and VFST by 1
LSB at the relative accuracy.
Vn: Analog input voltage when the output data changes from ânâ to
ân+1â (n = 0 to 1022)
⢠1LSB at relative accuracy â VFSTâV0T (V)
1022
⢠1LSB at absolute accuracy â VDD (V)
1024
⢠Absolute accuracy
This means a deviation from the ideal characteristics between 0
to VDD of actual A/D conversion characteristics.
Output data
1023
Full-scale transition voltage (VFST)
1022
Differential
non-linearity
error
=
bâa
a
[LSB]
Linearity error = c
a
[LSB]
b
a
n+1
n
Actual A/D conversion
characteristics
c
a: 1LSB by relative accuracy
b: Vn+1âVn
c: Difference between ideal Vn
and actual Vn
1
0
V0 V1
Zero transition voltage (V0T)
Ideal line of A/D conversion
between V0âV1022
Vn Vn+1
Fig. 32 Definition of A/D conversion accuracy
V1022
VDD
Analog voltage
Rev.3.01 2005.02.02 page 35 of 112
REJ03B0105-0301
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