ST STM32F10 Series Application Note

Power supplies
8/29 AN2586 Rev 8
On packages with 64 pins or less
The V
REF+
and V
REF-
pins are not available, they are internally connected to the ADC
voltage supply (V
DDA
) and ground (V
SSA
).
2.1.2 Battery backup
To retain the content of the Backup registers when V
DD
is turned off, the V
BAT
pin can be
connected to an optional standby voltage supplied by a battery or another source.
The V
BAT
pin also powers the RTC unit, allowing the RTC to operate even when the main
digital supply (V
DD
) is turned off. The switch to the V
BAT
supply is controlled by the power
down reset (PDR) circuitry embedded in the Reset block.
If no external battery is used in the application, it is highly recommended to connect V
BAT
externally to V
DD
.
2.1.3 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 1.8 V domain (core, memories
and digital peripherals)
• in Stop mode, the regulator supplies low power to the 1.8 V domain, preserving the
contents of the registers and SRAM
• in Standby mode, the regulator is powered off. The contents of the registers and SRAM
are lost except for those concerned with the Standby circuitry and the Backup domain.
2.2 Power supply schemes
The circuit is powered by a stabilized power supply, V
DD
.
• The V
DD
pins must be connected to V
DD
with external decoupling capacitors (one
100 nF ceramic capacitor for each V
DD
pin, plus one tantalum or ceramic capacitor
(min. 4.7 µF, typ.10 µF).
• The V
BAT
pin can be connected to the external battery (1.8 V < V
BAT
< 3.6 V). If no
external battery is used, it is recommended to connect this pin to V
DD
with a 100 nF
external ceramic decoupling capacitor.
• The V
DDA
pin must be connected to two external decoupling capacitors (100 nF
ceramic + 1 µF tantalum or ceramic).
• The V
REF+
pin can be connected to the V
DDA
external power supply. If a separate,
external reference voltage is applied on V
REF+
, a 100 nF and a 1 µF capacitors must be
connected on this pin. In all cases, V
REF+
must be kept between 2.4 V and V
DDA
.
• Additional precautions can be taken to filter analog noise:
–V
DDA
can be connected to V
DD
through a ferrite bead.
–The V
REF+
pin can be connected to V
DDA
through a resistor (typ. 47 Ω).
Caution: If the ADC is used, the V
DD
range is limited to 2.4 to 3.6 V (when the ADC is not used, the
V
DD
range is 2.0 to 3.6 V).

ST STM32F10 Series Specifications

General

Brand	ST
Model	STM32F10 Series
Category	Microcontrollers
Language	English