Sub-Ghz Radio Disable Lna Register (Reg_Ana_Lna); Sub-Ghz Radio Disable Mixer Register (Reg_Ana_Mixer); Sub-Ghz Radio Pa Over Current Protection Register; (Subghz_Paocpr) - ST STM32WL55JC Reference Manual

Power control (PWR)
Warning:
If no external battery is used in the application, it is recommended to connect VBAT
externally to V
When the Backup domain is supplied by V
following pins are available:
•
PC13, PC14 and PC15, that can be used as GPIO pins
• PC13, PC14 and PC15, that can be configured by RTC, TAMP or LSE (refer to
Section 32: Real-time clock (RTC)
(TAMP))
•
PA0/TAMP_IN2 and PB3/TAMP_IN3 when they are configured by the TAMP as tamper
pins
Note: Due to the fact that the analog switch can transfer only a limited amount of current (3 mA),
the use of GPIO PC13 to PC15 in output mode is restricted: the speed must be limited to
2 MHz with a maximum load of 30 pF and these I/Os must not be used as current source
(e.g. to drive a LED).
When the Backup domain is supplied by V
V is not present), the following functions are available:
DD
•
PC13, PC14 and PC15 can be controlled only by RTC, TAMP or LSE (refer to
Section 32: Real-time clock (RTC)
(TAMP))
•
PA0/TAMP_IN2 and PB3/TAMP_IN3, when they are configured by the TAMP as
tamper pins
Backup domain access
After a system reset, the Backup domain (RTC and TAMP backup registers) is protected
against possible unwanted write accesses. The DBP bit must be set in the
register 1 (PWR_CR1)
VBAT battery charging
When V
DD
internal resistance.
The VBAT charging is done either through a 5 kΩ resistor or through a 1.5 kΩ resistor,
depending on the VBRS bit value in the
222/1454
During
t
RSTTEMPO
is detected, the power switch between V
connected to V
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 VBAT pin cannot
support this current injection, it is strongly recommended to
connect an external low-drop diode between this power
supply and the VBAT pin.
with a 100 nF external ceramic decoupling capacitor.
DD
to enable access to the Backup domain
is present, It is possible to charge the external battery on VBAT through an
RM0453 Rev 2
(temporization at V
.
BAT
is established in less than
DD
+ 0.6 V, a current can be injected into V
).
BAT
(analog switch connected to V
DD
and Section 33: Tamper and backup registers
(analog switch connected to V
BAT
and Section 33: Tamper and backup registers
PWR control register 4
startup) or after a PDR
DD
and V remains
BAT DD
RSTTEMPO
BAT
and the
DD
), the
DD
BAT
PWR control
(PWR_CR4).
RM0453
)
because