ST STM8S Reference Manual

Power supply RM0016
72/449 Doc ID 14587 Rev 8
7 Power supply
The MCU has four distinct power supplies:
● V
DD
/V
SS
: Main power supply (3 V to 5.5 V)
● V
DDIO
/V
SSIO
: I/O power supply (3 V to 5.5 V)
● V
DDA
/V
SSA
: Power supply for the analog functions
● V
REF+
/V
REF-
: Reference supply for Analog Digital Converter
The V
DD
/V
SS
pins are used to supply the internal Main Voltage Regulator (MVR) and the
internal Low Power Voltage Regulator (LPVR). The 2 regulator outputs are connected and
provide the 1.8 V supply (V
18
) to the MCU core (CPU, Flash and RAM)
In low power modes the system automatically switches from the MVR to the LPVR in order
to reduce current consumption.
To stabilize the MVR, a capacitor must be connected to the VCAP pin (for more details refer
to the datasheet electrical characteristics section).
Depending on the package size, there are one or two pairs of dedicated pins for
V
DDIO
/V
SSIO
to supply power to the I/Os.
V
DDA
/V
SSA
and V
REF+
/V
REF-
are connected to the Analog to Digital Converter (ADC).
Figure 17. Power supply overview
Low Power Voltage Regulator
V
DD
V
CAP
V
DDIO
Main Voltage Regulator
I/O buffers
MCU core
1.8V
3V-5.5V
RAM
Flash
3V-5.5V
A/D converter
V
DDA
V
SSA
3V-5.5V
V
REF+
V
REF-
CPU
V
18

ST STM8S Specifications

General

Brand	ST
Model	STM8S
Category	Microcontrollers
Language	English