
ST72321xx-Auto Electrical characteristics
Doc ID 13829 Rev 1 219/243
19.12.3 ADC accuracy
Conditions: V
DD
=5V
(1)
Figure 101. ADC error classification
Table 136. ADC accuracy
Symbol Parameter
(1)
1. ADC Accuracy versus Negative Injection Current: Injecting negative current may reduce the accuracy of
the conversion being performed on another analog input.
Any positive injection current within the limits specified for I
INJ(PIN)
and I
INJ(PIN)
in Section 19.8 does not
affect the ADC accuracy.
Conditions Typ Max
(2)
2. Data based on characterization results, monitored in production to guarantee 99.73% within ± max value
from -40°C to 125°C (± 3distribution limits).
Unit
|E
T
| Total unadjusted error
CPU in run mode @ f
ADC
2 MHz
34
LSB
|E
O
| Offset error 2 3
|E
G
| Gain error 0.5 3
|E
D
| Differential linearity error
12
|E
L
| Integral linearity error
E
O
E
G
1LSB
IDEAL
1LSB
IDEAL
V
AREF
V
SSA
–
1024
--------------------------------------------=
V
in
(LSB
IDEAL
)
Digital Result ADCDR
1023
1022
1021
5
4
3
2
1
0
7
6
1234567
1021 1022 1023 1024
(1)
(2)
E
T
E
D
E
L
(3)
V
AREF
V
SSA
Legend:
(1) Example of an actual transfer curve
(2) The ideal transfer curve
(3) End point correlation line
E
T
= Total Unadjusted Error: maximum deviation
between the actual and the ideal transfer curves.
E
O
= Offset Error: deviation between the first
actual transition and the first ideal one.
E
G
= Gain Error: deviation between the last ideal
transition and the last actual one.
E
D
= Differential Linearity Error: maximum
deviation between actual steps and the ideal
one.
E
L
= Integral Linearity Error: maximum deviation
between any actual transition and the end point
correlation line.
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