Specifications

ST72104Gx, ST72215Gx, ST72216Gx, ST72254Gx
129/141
8-BIT ADC CHARACTERISTICS (Cont’d)
ADC Accuracy
Figure 96. ADC Accuracy Characteristics
Notes:
1. ADC Accuracy vs. Negative Injection Current:
For I
INJ-
=0.8mA, the typical leakage induced inside the die is 1.6µA and the effect on the ADC accuracy is a loss of 1 LSB
for each 10KΩ increase of the external analog source impedance. This effect on the ADC accuracy has been observed
under worst-case conditions for injection:
- negative injection
- injection to an Input with analog capability, adjacent to the enabled Analog Input
- at 5V V
DD
supply, and worst case temperature.
2. Data based on characterization results with T
A
=25°C.
3. Data based on characterization results over the whole temperature range.
Symbol Parameter
V
DD
=5V,
2)
f
CPU
=1MHz
V
DD
=5.0V,
3)
f
CPU
=8MHz
V
DD
=3.3V,
3)
f
CPU
=8MHz
Unit
Min Max Min Max Min Max
|E
T
| Total unadjusted error
1)
2.0 2.0 2.0
LSB
E
O
Offset error
1)
1.5 1.5 1.5
E
G
Gain Error
1)
1.5 1.5 1.5
|E
D
| Differential linearity error
1)
1.5 1.5 1.5
|E
L
| Integral linearity error
1)
1.5 1.5 1.5
E
O
E
G
1LSB
IDEAL
1LSB
IDEAL
V
DDA
V
SSA
–
256
-----------------------------------------=
V
in
(LSB
IDEAL
)
(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.
Digital Result ADCDR
255
254
253
5
4
3
2
1
0
7
6
1234567
253 254 255 256
(1)
(2)
E
T
E
D
E
L
(3)
V
DDA
V
SSA