Analog-To-Digital Converter (Adc); Analog Power; Analog Input; Figure 4. Analog Input Interface - ST STM8S Application Note

Analog-to-digital converter (ADC)

3 Analog-to-digital converter (ADC)
3.1

Analog power

The ADC unit has an independent, analog supply reference voltage, isolated on input pin
V , which allows the ADC to accept a very clean voltage source. This analog voltage
DDA
supply range is the same as the digital voltage supply range on pin V
supply ground connection on pin V
analog supply voltage and analog supply ground connection, offer a separate external
analog reference voltage input for the ADC unit on the V
on low voltage input as follows:
● V
REF+
ADC should be between [250 mV, V
refer to the Root part number 2 datasheet. This input is bonded to V
have no external V
● V
REF-
ADC should be higher than V
the Root part number 2 datasheet. This input is bonded to V
external V
3.2

Analog input

Root part number 2 devices have 16 analog input channels, which are converted by the
ADC one at a time, and each multiplexed with an I/O.
The analog input interface of the ADC is shown in
Figure 4.
10/42
(input, analog reference positive): The higher/positive reference voltage for the
pin (packages with 48 pins or less).
REF+
(input, analog reference negative): The lower/negative reference voltage for the
pin (packages with 48 pins or less).
REF-
Analog input interface
Outside ADC
V
R
IN_EXT EXT
Doc ID 14651 Rev 3
provides further ADC supply isolation. Together, the
SSA
REF+
]. For more details about V
DDA
. For more details about V
SSA
Figure
SW
V
SAMP
IN
C
EXT
. An isolated analog
DD
pin. This gives better accuracy
values please
REF+
in devices that
DDA
values please refer to
REF-
in devices that have no
SSA
4.
Inside ADC
C
SAMP
AN2752