ST STM32F102 series User Manual

RM0008 Power control (PWR)
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4.1.1 Independent A/D converter supply and reference voltage
To improve conversion accuracy, the ADC has an independent power supply which can be
separately filtered and shielded from noise on the PCB.
● The ADC voltage supply input is available on a separate V
DDA
pin.
● An isolated supply ground connection is provided on pin V
SSA
.
When available (according to package), V
REF-
must be tied to V
SSA
.
On 100-pin and 144- pin packages
To ensure a better accuracy on low voltage inputs, the user can connect a separate external
reference voltage ADC input on V
REF+
and V
REF-
. The voltage on V
REF+
can range from
2.4 V to V
DDA
.
On 64-pin packages
The V
REF+
and V
REF-
pins are not available, they are internally connected to the ADC
voltage supply (V
DDA
) and ground (V
SSA
).
4.1.2 Battery backup domain
To retain the content of the Backup registers and supply the RTC function when V
DD
is
turned off, V
BAT
pin can be connected to an optional standby voltage supplied by a battery or
by another source.
The V
BAT
pin powers the RTC unit, the LSE oscillator and the PC13 to PC15 IOs, allowing
the RTC to operate even when the main digital supply (V
DD
) is turned off. The switch to the
V
BAT
supply is controlled by the Power Down Reset embedded in the Reset block.
Warning: During t
RSTTEMPO
(temporization at V
DD
startup) or after a PDR
is detected, the power switch between V
BAT
and V
DD
remains
connected to V
BAT
.
During the startup phase, if V
DD
is established in less than
t
RSTTEMPO
(Refer to the datasheet for the value of t
RSTTEMPO
)
and V
DD
> V
BAT
+ 0.6 V, a current may be injected into V
BAT
through an internal diode connected between V
DD
and the
power switch (V
BAT
).
If the power supply/battery connected to the V
BAT
pin cannot
support this current injection, it is strongly recommended to
connect an external low-drop diode between this power
supply and the V
BAT
pin.
As V
DD
rises fast and may become established during this time, a current may be injected
into V
BAT
through a diode connected between V
DD
and V
BAT
when V
BAT
is lower than V
DD
−
0.6V
. Refer to the datasheet for the value of t
RSTTEMPO.
If no external battery is used in the application, it is recommended to connect V
BAT
externally to V
DD
through a 100 nF external ceramic capacitor (for more details refer to
AN2586).

ST STM32F102 series Specifications

General

Brand	ST
Model	STM32F102 series
Category	Microcontrollers
Language	English