Voltage Regulator; Power Supply Scheme - ST STM32F74 Series Getting Started

AN4661
When the backup domain is supplied by V
V is not present), the following functions are available:
DD
•
PC14 and PC15 can be used as LSE pins only.
•
PC13 can be used as tamper pin (TAMP1).
•
PI8 can be used as tamper pin (TAMP2).
1.1.4

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 1.2 V domain (core, memories
and digital peripherals).
•
In Stop mode, the regulator supplies low power to the 1.2 V domain, preserving the
contents of the registers and SRAM.
• In Standby mode, the regulator is powered down. The contents of the registers and
SRAM are lost except for those concerned with the standby circuitry and the backup
domain.
Note: Depending on the selected package, there are specific pins that should be connected either
to V or V
SS
section in the datasheet for more details.
1.2

Power supply scheme

•
V
DD
enabled), provided externally through V
V
DD
(min. 4.7 μF) for the package + one 100 nF ceramic capacitor for each V
•
V
SSA
blocks, RCs and PLL. V
The V
ceramic + 1 μF tantalum or ceramic).
•
V
DDUSB
to 3.6V) for USB transceivers. For example, when the device is powered at 1.8V, an
independent power supply 3.3V can be connected to V
The V
ceramic + 1 μF tantalum or ceramic).
•
V
BAT
backup registers (through power switch) when V
The V
external battery is used, it is recommended to connect this pin to V
external ceramic decoupling capacitor.
Note: V /V
DD DDA
Section 1.3.5: Internal reset
•
The V
external reference voltage is applied on V
to activate or deactivate the voltage regulator. Refer to the voltage regulator
DD
= 1.7 to 3.6 V: external power supply for I/Os and the internal regulator (when
with external decoupling capacitors: one single tantalum or ceramic capacitor
, V = 1.7 to 3.6 V: external analog power supplies for ADC, DAC, Reset
DDA
DDA
pin must be connected to two external decoupling capacitors (100 nF
DDA
can be connected either to V
pin must be connected to two external decoupling capacitors (100 nF
DDUSB
= 1.65 to 3.6 V: power supply for RTC, external clock 32 kHz oscillator and
pin can be connected to the external battery (1.65 V < V
BAT
minimum value of 1.7 V is obtained when the internal reset is OFF (refer to
OFF).
pin can be connected to the V
REF+
DocID027559 Rev 2
(analog switch connected to V
BAT
pins. The V
DD
and V must be connected to V
SSA
or an external independent power supply (3.0
DD
DD
external power supply. If a separate,
DDA
, a 100 nF and a 1 μF capacitors must be
REF+
Power supplies
BAT
pins must be connected to
DD
DD
and V
DD SS
.
DDUSB
is not present.
< 3.6 V). If no
BAT
with a 100 nF
DD
because
pin.
, respectively.
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