Datasheet

Functional overview STM32F37xxx
14/131 DocID022691 Rev 4
3.7 Power management
3.7.1 Power supply schemes
• V
DD
:
external power supply for I/Os and the internal regulator. It is provided externally
through V
DD
pins, and can be 2.0 to 3.6 V.
• V
DDA
= 2.0 to 3.6 V:
– external analog power supplies for Reset blocks, RCs and PLL
– supply voltage for 12-bit ADC, DACs and comparators (minimum voltage to be
applied to V
DDA
is 2.4 V when the 12-bit ADC and DAC are used).
• V
DDSD12
and V
DDSD3
= 2.2 to 3.6 V: supply voltages for SDADC1/2 and SDADCD3
sigma delta ADCs. Independent from V
DD
/V
DDA
.
• V
BAT
= 1.65 to 3.6 V: power supply for RTC, external clock 32 kHz oscillator and
backup registers when V
DD
is not present.
3.7.2 Power supply supervisor
• The device has an integrated power-on reset (POR)/power-down reset (PDR) circuitry.
It is always active, and ensures proper operation starting from/down to 2 V. The device
remains in reset mode when V
DD is below a specified threshold, VPOR/PDR, without the
need for an external reset circuit. The POR monitors only the V
DD
supply voltage.
During the startup phase it is required that V
DDA
should arrive first and be greater than
or equal to V
DD
.
• The PDR monitors both the V
DD
and V
DDA
supply voltages, however the V
DDA
power
supply supervisor can be disabled (by programming a dedicated Option bit) to reduce
the power consumption if the application design ensures that V
DDA
is higher than or
equal to V
DD
.
The device features an embedded programmable voltage detector (PVD) that monitors the
V
DD
power supply and compares it to the VPVD threshold. An interrupt can be generated
when V
DD
drops below the V
PVD
threshold and/or when V
DD
is higher than the V
PVD
threshold. The interrupt service routine can then generate a warning message and/or put
the MCU into a safe state. The PVD is enabled by software.
3.7.3 Voltage regulator
The regulator has three operation modes: main (MR), low power (LPR), and power-down.
• The MR mode is used in the nominal regulation mode (Run)
• The LPR mode is used in Stop mode.
• The power-down mode is used in Standby mode: the regulator output is in high
impedance, and the kernel circuitry is powered down thus inducing zero consumption.
The voltage regulator is always enabled after reset. It is disabled in Standby mode.