4507 Datasheet, PDF (35/115 Pages) Renesas Technology Corp – SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

4507 Group
(15) Definition of A/D converter accuracy
The A/D conversion accuracy is defined below (refer to Figure 32).
• Relative accuracy
➀ Zero transition voltage (V0T)
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 Linearity error
This means a deviation from the line between V0T and VFST of
a converted value between V0T and VFST.
➃ 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 “n” to
“n+1” (n = 0 to 1022)
• 1LSB at relative accuracy → ^{VFST–V0T} (V)
1022
• 1LSB at absolute accuracy → ^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
=
b–a
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+1–Vn
c: Difference between ideal Vn
and actual Vn
1
0
V0 V1
Zero transition voltage (V0T)
Ideal line of A/D conversion
between V0–V1022
Vn Vn+1
Fig. 32 Definition of A/D conversion accuracy
V1022
VDD
Analog voltage
Rev.3.01 2005.02.04 page 35 of 111
REJ03B0107-0301