Independent Analog Converter Supply; Battery Backup - ST STM32F0 Series Application Note

Power supplies of the STM32F06xxx family
2.1.1

Independent analog converter supply

To improve conversion accuracy and to extend the supply flexibility, the analog domain has
an independent power supply which can be separately filtered and shielded from noise on
the PCB.
● The ADC and DAC voltage supply input is available on a separate VDDA pin.
●
An isolated supply ground connection is provided on pin VSSA.
The V
DDA
while still keeping V
When a single supply is used, V
recommended to use an external filtering circuit in order to ensure a noise free V
When V
DDA
potential difference between V
Schottky diode may be used between V
maximum allowed difference.
Figure 7.
2.1.2

Battery backup

To retain the content of the Backup registers when V
connected to an optional standby voltage supplied by a battery or another source.
The V
BAT
digital supply (V
The switch to the Vbat supply is controlled by the NPOR pin (Negative Power On Reset).
If no external battery is used in the application, it is recommended to connect V
externally to V
12/29
supply can be equal to or higher than V
low.
DD
is different from V
DD
DDA
Schottky diode connection
V
DD
pin also powers the RTC unit, allowing the RTC to operate even when the main
) is turned off.
DD
.
DD
Doc ID 023035 Rev 2
. This allows full analog performance
DD
must be externally connected to V
DDA
, V must be always higher or equal to V
DDA
and V during power-up/power-down, an external
DD
and V . Refer to the datasheet for the
DD DDA
VDD VDDA
Schottky diode
DD
,. It is
DD
DD
V
DDA
is turned off, the V
BAT
AN4080
.
DDA
. To keep safe
MS30272V1
pin can be
BAT