Voltage Regulator - STMicroelectronics RM0365 Reference Manual

Power control (PWR)
Warning:
If no external battery is used in the application, it is recommended to connect V
externally to V
to AN4206).
When the RTC domain is supplied by V
functions are available:
•
PC13, PC14 and PC15 can be used as GPIO pins
•
PC13, PC14 and PC15 can be configured by RTC or LSE (refer to
functional description on page
Note: Due to the fact that the switch only sinks a limited amount of current (3 mA), the use of
GPIOs PC13 to PC15 in output mode is restricted: the speed has to be limited to 2 MHz with
a maximum load of 30 pF and these I/Os must not be used as a current source (e.g. to drive
an LED).
When the RTC domain is supplied by V
is not present), the following functions are available:
•
PC13, PC14 and PC15 can be controlled only by RTC or LSE (refer to
RTC functional description on page
8.1.3

Voltage regulator

The voltage regulator is always enabled after Reset. It works in three different modes
depending on the application modes.
•
In Run mode, the regulator supplies full power to the 1.8 V domain (core, memories
and digital peripherals).
•
In Stop mode the regulator supplies low-power to the 1.8 V domain, preserving
contents of registers and SRAM.
• In Standby Mode, the regulator is powered off. The contents of the registers and SRAM
are lost except for the Standby circuitry and the RTC Domain.
99/1080
During
t
RSTTEMPO
is detected, the power switch between V
connected to V
BAT
During the startup phase, if V
t (Refer to the datasheet for the value of t
RSTTEMPO
and V > V
DD BAT
through an internal diode connected between V
power switch (V
If the power supply/battery connected to the V
support this current injection, it is strongly recommended to
connect an external low-drop diode between this power
supply and the V
with a 100 nF external ceramic decoupling capacitor (for more details refer
DD
724)
DocID025202 Rev 7
(temporization at V
DD
.
is established in less than
DD
+ 0.6 V, a current may be injected into V
).
BAT
pin.
BAT
(analog switch connected to V
DD
(analog switch connected to V
BAT
724)
startup) or after a PDR
and V remains
BAT DD
RSTTEMPO
BAT
and the
DD
pin cannot
BAT
BAT
), the following
DD
Section 27.3: RTC
because V
BAT
Section 27.3:
RM0365
)
DD