38K2 Datasheet, PDF (126/151 Pages) Renesas Technology Corp – SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER

38K2 Group
Definition of A/D Conversion Accuracy
The A/D conversion accuracy is defined below (refer to Figure
167).
•Relative accuracy
➀ Zero transition voltage (VOT)
This means an analog input voltage when the actual A/D con-
version output data changes from “0” to “1.”
➁ Full-scale transition voltage (VFST)
This means an analog input voltage when the actual A/D con-
version output data changes from “1023” to “1022.”
➂ Non-linearity error
This means a deviation from the line between VOT and VFST of
a converted value between VOT and VFST.
➃ Differential non-linearity error
This means a deviation from the input potential difference re-
quired to change a converted value between VOT and VFST by 1
LSB of the 1 LSB at the relative accuracy.
•Absolute accuracy
This means a deviation from the ideal characteristics between 0 to
VREF of actual A/D conversion characteristics.
Output data
1023
Full-scale transition voltage (VFST)
1022
Differential non-linearity error=
b-a
a
[LSB]
Non-linearity error=
c
a
[LSB]
b
a
n+1
n
Actual A/D conversion
characteristics
c
a: 1LSB at relative accuracy
b: Vn+1-Vn
c: Difference between
the ideal Vn and actual Vn
Ideal line of A/D
conversion between
V0 to V1022
1
0
V0 V1
Zero transition voltage (V0T)
Vn Vn+1
Fig. 167 Definition of A/D conversion accuracy
V1022 _{Analog voltage} VREF
Vn: Analog input voltage when the output data changes from “n” to “n + 1” (n = 0 to 1022)
• 1 LSB at relative accuracy →
VFST – VOT
1022
(V)
• 1 LSB at absolute accuracy →
VREF
1024
(V)
Rev.3.00 Oct 15, 2006 page 126 of 147
REJ03B0193-0300