RM0091 Power control (PWR)
Doc ID 018940 Rev 1 67/742
6 Power control (PWR)
6.1 Power supplies
The device requires a 2.0 V - 3.6 V operating voltage supply (V
DD
) and 2.0 V - 3.6 V analog
voltage supply (V
DDA
). An embedded regulator is used to supply the internal 1.8 V digital
power.
The real-time clock (RTC) and backup registers can be powered from the V
BAT
voltage when
the main V
DD
supply is powered off.
Figure 6. Power supply overview
6.1.1 Independent A/D and D/A converter supply and reference voltage
To improve conversion accuracy and to extend the supply flexibility, the ADC and the DAC
have 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 V
DDA
pin.
● An isolated supply ground connection is provided on pin V
SSA
.
The V
DDA
supply/reference voltage can be equal or higher than V
DD
.
When a single supply is used, V
DDA
can be externally connected to V
DD
, through the
external filtering circuit in order to ensure a noise free V
DDA
/reference voltage.
A/D converter
V
DD
V
BAT
V
SS
I/O Ring
V
DDA
BKP registers
Temp. sensor
Reset block
Standby circuitry
PLL
(Wakeup logic,
IWDG)
RTC
Voltage Regulator
Core
Memories
digital
peripherals
Low voltage detector
V
DDA
domain
V
DD
domain
1.8 V domain
Backup domain
LSE crystal 32K osc
RCC BDCR register
V
SSA
D/A converter
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