ST STM32F40 Series Reference Manual page 93

Power controller (PWR)
When activated by software, 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 this mode, the regulator output voltage (around 1.2 V) can
be scaled by software to different voltage values:
–
–
The voltage scaling allows optimizing the power consumption when the device is
clocked below the maximum system frequency.
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In Stop mode the regulator supplies low power to the 1.2 V domain, preserving the
content of registers and internal SRAM.
–
–
●
In Standby mode, the regulator is powered down. The content of the registers and
SRAM are lost except for the Standby circuitry and the backup domain.
Note: For more details, refer to the voltage regulator section in the STM32F4xx datasheets.
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For STM32F405xx/07xx and STM32F415xx/17xx
Scale 1 or scale 2 can be configured on the fly through VOS (bit 15 of the
PWR_CR register).
For STM32F42xxx and STM32F43xxx
Scale 1, scale 2, or scale 3 can be configured through VOS[1:0] bits of the
PWR_CR register). The scale can be modified only when the PLL is OFF and the
HSI or HSE clock source is selected as system clock source. The new value
programmed is active only when the PLL is ON
selected when PLL is OFF (see
(PWR_CR) for STM32F42xxx and
For STM32F405xx/07xx and STM32F415xx/17xx
The programmed voltage scale remains the same during Stop mode (see
Section 5.4.1: PWR power control register (PWR_CR) for STM32F405xx/07xx
and STM32F415xx/17xx.
For STM32F42xxx and STM32F43xxx
Voltage scale 3 is automatically selected when the microcontroller enters Stop
mode (see Section 5.4.2: PWR power control register (PWR_CR) for
STM32F42xxx and STM32F43xxx).
Doc ID 018909 Rev 4
.
Voltage scale 3 is automatically
Section 5.4.2: PWR power control register
STM32F43xxx).
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