Datasheet
Electrical characteristics STM32F37xxx
100/131 DocID022691 Rev 4
Figure 29. ADC accuracy characteristics
Figure 30. Typical connection diagram using the ADC
1. Refer to Table 60 for the values of R
SRC
, R
ADC
and C
ADC
.
2. C
parasitic
represents the capacitance of the PCB (dependent on soldering and PCB layout quality) plus the
pad capacitance (roughly 7 pF). A high C
parasitic
value will downgrade conversion accuracy. To remedy
this, f
ADC
should be reduced.
General PCB design guidelines
Power supply decoupling should be performed as shown in Figure 9. The 10 nF capacitor
should be ceramic (good quality) and it should be placed as close as possible to the chip.
2. ADC accuracy vs. negative injection current: Injecting a negative current on any analog input pins should
be avoided as this significantly reduces the accuracy of the conversion being performed on another analog
input. It is recommended to add a Schottky diode (pin to ground) to analog pins which may potentially inject
negative currents.
Any positive injection current within the limits specified for I
INJ(PIN)
and ΣI
INJ(PIN)
in Section 6.3.14 does not
affect the ADC accuracy.
3. Better performance may be achieved in restricted V
DDA
, frequency and temperature ranges.
4. Data based on characterization results, not tested in production.
E
O
E
G
1LSB
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.
4095
4094
4093
5
4
3
2
1
0
7
6
1234567
4093 4094 4095 4096
(1)
(2)
E
T
E
D
E
L
(3)
V
DDA
V
SSA
MS19880V1
MS32163V1
V
DD
AINx
I
L
±1 μA
0.6 V
V
T
R
SRC
(1)
C
parasitic
SRC
0.6 V
V
T
R
ADC
(1)
12-bit
converter
C
ADC
(1)
Sample and hold ADC
converter
7