Datasheet

4. The gain accuracy represents the gain error expressed in percent. Gain accuracy (%) = (Gain Error
in V x 100) / (V
ref
/GAIN)
39.6.4 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 (
SAMPLE
) and a
capacitor (
SAMPLE
). In addition, the source resistance (
SOURCE
) must be taken into account when
calculating the required sample and hold time. The next figure shows the ADC input channel equivalent
circuit.
Figure 39-3. ADC Input
R
SOURCE
R
SAMPLE
Analog Input
AINx
C
SAMPLE
V
IN
VDDANA/2
To achieve n bits of accuracy, the 
SAMPLE
capacitor must be charged at least to a voltage of

CSAMPLE
 
IN
× 1 +  2
  + 1
The minimum sampling time 
SAMPLEHOLD
for a given 
SOURCE
can be found using this formula:

SAMPLEHOLD
 
SAMPLE
+ 
SOURCE
× 
SAMPLE
×  + 1 × ln 2
for a 12 bits accuracy:

SAMPLEHOLD
 
SAMPLE
+ 
SOURCE
× 
SAMPLE
× 9.02
where

SAMPLEHOLD
=
1
2 × 
ADC
39.6.5 Digital to Analog Converter (DAC) Characteristics
Table 39-19. Operating Conditions
(1)
(Device Variant A)
Symbol Parameter Conditions Min. Typ. Max. Units
V
DDANA
Analog supply voltage 1.62 - 3.63 V
AV
REF
External reference voltage 1.0 - V
DDANA
-0.6 V
Internal reference voltage 1 - 1 - V
Internal reference voltage 2 - V
DDANA
- V
Linear output voltage range 0.05 - V
DDANA
-0.05 V
Minimum resistive load 5 - - kΩ
SAM D21 Family
Electrical Characteristics at 125°C
© 2018 Microchip Technology Inc.
Datasheet Complete
DS40001882D-page 1081