ST STM32L4 5 Series - Power Control (PWR); Power Supplies

Power control (PWR) RM0351
150/1830 DocID024597 Rev 5
5 Power control (PWR)
5.1 Power supplies
The STM32L4x5/STM32L4x6 devices require a 1.71 V to 3.6 V operating supply voltage
(V
DD
). Several peripherals are supplied through independent power domains: V
DDA
,
V
DDIO2
, V
DDUSB
, V
LCD
. Those supplies must not be provided without a valid operating
supply on the V
DD
pin.
• V
DD
= 1.71 V to 3.6 V
V
DD
is the external power supply for the I/Os, the internal regulator and the system
analog such as reset, power management and internal clocks. It is provided externally
through VDD pins.
• VDD12 = 1.05 V to 1.32 V
External power supply, connected to V
CORE
, bypassing internal regulator when
connected to an external SMPS. It is provided externally through VDD12 pins and only
available on packages with the external SMPS supply option.
• V
DDA
= 1.62 V (ADCs/COMPs) / 1.8 V (DACs/OPAMPs) / 2.4 V (VREFBUF) to 3.6 V
V
DDA
is the external analog power supply for A/D converters, D/A converters, voltage
reference buffer, operational amplifiers and comparators. The V
DDA
voltage level is
independent from the V
DD
voltage. V
DDA
should be preferably connected to V
DD
when
these peripherals are not used.
• V
DDUSB
= 3.0V to 3.6V
V
DDUSB
is the external independent power supply for USB transceivers. The V
DDUSB
voltage level is independent from the V
DD
voltage. V
DDUSB
should be preferably
connected to V
DD
when the USB is not used.
• V
DDIO2
= 1.08 V to 3.6 V
V
DDIO2
is the external power supply for 14 I/Os (Port G[15:2]). The V
DDIO2
voltage level
is independent from the V
DD
voltage and should preferably be connected to V
DD
when
PG[15:2] are not used.
• V
LCD
= 2.5 V to 3.6 V
The LCD controller can be powered either externally through VLCD
pin, or internally
from an internal voltage generated by the embedded step-up converter. VLCD is
multiplexed with PC3 which can be used as GPIO when the LCD is not used.
• V
BAT
= 1.55 V to 3.6 V
V
BAT
is the power supply for RTC, external clock 32 kHz oscillator and backup registers
(through power switch) when V
DD
is not present. VBAT is internally bonded to VDD for
small packages without dedicated pin.
• V
REF-, VREF+
V
REF+
is the input reference voltage for ADCs and DACs. It is also the output of the
internal voltage reference buffer when enabled.
When V
DDA
< 2 V, V
REF+
must be equal to V
DDA
.
When V
DDA
 2 V, V
REF+
must be between 2 V and V
DDA
.
V
REF+
can be grounded when ADC and DAC are not active.
The internal voltage reference buffer supports two output voltages, which are
configured with VRS bit in the VREFBUF_CSR register:
–V
REF+
around 2.048 V. This requires V
DDA
equal to or higher than 2.4 V.