Datasheet

Table Of Contents
DS13105 Rev 4 23/135
STM32WLE5J8/JB/JC Functional overview
46
VREF-, VREF+
V
REF+
is the input reference voltage for ADC. 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 is not active. The internal voltage reference buffer
supports the following output voltages, configured with VRS bit in the VREFBUF_CSR
register:
–V
REF+
around 2.048 V: this requires V
DDA
2.4 V.
–V
REF+
around 2.5 V: this requires V
DDA
2.8 V.
During power up and power down, the following power sequence is required:
1. When V
DD
< 1 V other power supplies (V
DDA
) must remain below V
DD
+ 300 mV.
During power down, V
DD
can temporarily become lower then other supplies only if the
energy provided to the device remains below 1 mJ. This allows external decoupling
capacitors to be discharged with different time constants during this transient phase.
2. When V
DD
> 1 V, all other power supplies (V
DDA
) become independent.
An embedded linear voltage regulator is used to supply the internal digital power V
CORE
.
V
CORE
is the power supply for digital peripherals, SRAM1 and SRAM2. The Flash memory
is supplied by V
CORE
and V
DD
. V
CORE
is split in two parts: V
DDO
part and an interruptible
part V
DDI
.
Figure 5. Power supply overview
MSv50973V1
LDO/SMPS
MR
V
DD
V
LXSMPS
V
FBSMPS
V
BKP
V
DDO
V
DDI
V
BAT
V
RF
V
MAIN
V
LP
V
SW
POR
mode
FW mode
en
RFLDO
V
DDSMPS
V
DDRF1V5
LPR