ST STM32L0x3 User Manual

RM0367 Rev 7 145/1043
RM0367 Power control (PWR)
172
6.1.4 Voltage regulator
An embedded linear voltage regulator supplies all the digital circuitries except for the
Standby circuitry. The regulator output voltage (V
CORE
) can be programmed by software to
three different ranges within 1.2 - 1.8 V (typical) (see Section 6.1.5).
The voltage regulator is always enabled after Reset. It works in three different modes: main
(MR), low-power (LPR) and power-down, depending on the application modes.
• In Run mode, the regulator is main (MR) mode and supplies full power to the V
CORE
domain (core, memories and digital peripherals).
• In Low-power run mode, the regulator is in low-power (LPR) mode and supplies low-
power to the V
CORE
domain, preserving the contents of the registers and internal
SRAM.
• In Sleep mode, the regulator is main (MR) mode and supplies full power to the V
CORE
domain, preserving the contents of the registers and internal SRAM.
• In Low-power sleep mode, the regulator is in low-power (LPR) mode and supplies low-
power to the V
CORE
domain, preserving the contents of the registers and internal
SRAM.
• In Stop mode the regulator supplies low power to the V
CORE
domain, preserving the
content of registers and internal SRAM.
• In Standby mode, the regulator is powered off. The content of the registers and SRAM
are lost except for the Standby circuitry.
6.1.5 Dynamic voltage scaling management
The dynamic voltage scaling is a power management technique which consists in
increasing or decreasing the voltage used for the digital peripherals (V
CORE
), according to
the circumstances.
Dynamic voltage scaling to increase V
CORE
is known as overvolting. It allows improving the
device performance. Refer to Figure 11 for a description of the device operating conditions
versus CPU performance and to the datasheet electrical characteristics for ADC clock
frequency versus dynamic range.
Dynamic voltage scaling to decrease V
CORE
is known as undervolting. It is performed to
save power, particularly in laptops and other mobile devices where the energy comes from a
battery and is thus limited.
Range 1
Range 1 is the “high performance” range.
The voltage regulator outputs a 1.8 V voltage (typical) as long as the V
DD
input voltage is
above 1.71 V. Flash program and erase operations can be performed in this range.
The clock recovery system (CRS) is available only when the device operates in range 1
(see Section 8: Clock recovery system (CRS)).
When V
DD
is below 2.0 V, the CPU frequency changes from initial to final state must respect
the following conditions:
• f
CPUfinal
< 4xf
CPUinitial
.
• In addition, a 5 μs delay must be respected between two changes. For example to
switch from 4.2 to 32 MHz, switch from 4.2 to 16 MHz, wait for 5 μs, then switch from
16 to 32 MHz.

ST STM32L0x3 Specifications

General

Brand	ST
Model	STM32L0x3
Category	Microcontrollers
Language	English