Atmel Xplained Pro Evaluation Kit for the ATSAMD21J18A Microcontroller ATSAMD21-XPRO ATSAMD21-XPRO Fiche De Données
Codes de produits
ATSAMD21-XPRO
943
Atmel | SMART SAM D21 [DATASHEET]
Atmel-42181C–SAM-D21_Datasheet–07/2014
(GAINCORR). The offset and gain correction value is subtracted from the converted data before writing the Result
register (RESULT).
register (RESULT).
Table 36-24. Offset and Gain correction feature
36.9.4.3 Inputs and Sample and Hold Acquisition Times
The analog voltage source must be able to charge the sample and hold (S/H) capacitor in the ADC in order to achieve
maximum accuracy. Seen externally the ADC input consists of a resistor (
maximum accuracy. Seen externally the ADC input consists of a resistor (
) and a capacitor (
). In
addition, the source resistance (
) must be taken into account when calculating the required sample and hold
shows the ADC input channel equivalent circuit.
Figure 36-3. ADC Input
To achieve n bits of accuracy, the
capacitor must be charged at least to a voltage of
The minimum sampling time
for a given
can be found using this formula:
for a 12 bits accuracy:
Gain Factor
Conditions
Offset Error
(mV)
Gain Error
(mV)
Total Unadjusted Error
(LSB)
0.5x
In differential mode, 1x gain,
V
DDANA
=3.0V,
V
REF
=1.0V, 350kSps
0.25
1.0
2.4
1x
0.20
0.10
1.5
2x
0.15
-0.15
2.7
8x
-0.05
0.05
3.2
16x
0.10
-0.05
6.1
R
SAMPLE
C
SAMPLE
R
SOURCE
R
SOURCE
R
SAMPLE
Analog Input
AINx
C
SAMPLE
V
IN
VDDANA/2
C
SAMPLE
V
CSAMPLE
V
≥
IN
1 2
n 1
+
(
)
–
–
(
)
×
t
SAMPLEHOLD
R
SOURCE
t
SAMPLEHOLD
R
SAMPLE
R
+
SOURCE
(
)
C
SAMPLE
(
)
×
n 1
+
(
)
2
( )
ln
×
×
≥
t
SAMPLEHOLD
R
SAMPLE
R
+
SOURCE
(
)
C
SAMPLE
(
)
×
9.02
×
≥