AN4365 datasheet(7/35 Pages) STMICROELECTRONICS

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AN4365

STM32F4 power consumption

STM32F4 devices feature four main low-power modes:

•

Sleep mode:

–

Only the CPU clock is stopped.

The Cortex-M4 clock is stopped and the peripherals are kept running. The current

consumption increases with the clock frequency. As in Run mode, the user should be

aware of system configuration rules that concern the system clock and voltage

regulator scales.

•

Stop mode:

–

Lowest power consumption while all the SRAM and registers are kept.

–

PLL, HSI, HSE are disabled.

–

All clocks in 1.2 V domain are switched-off.

–

Voltage regulator is working in Normal mode or Low-power mode.

–

Flash memory is working in Stop mode or Deep-power down mode.

The Cortex-M4 core is stopped and the clocks are switched off (the PLL, the HSI and

the HSE are disabled). SRAM and register content are kept. All I/O pins keep the same

state as the Run mode. The voltage regulator is working in Normal or Low-power mode

and the Flash memory can be configured in Stop mode or Deep-power down mode to

save more static power.

•

Standby mode:

–

The lowest power consumption.

–

The 1.2 domain is powered off (regulator is disabled).

–

SRAM and register contents are lost except in the backup domain.

The Cortex-M4 core is stopped and the clocks are switched off. The voltage regulator is

disabled and the 1.2 V domain is powered-off. SRAM and register contents are lost

except for registers in the Backup domain (RTC registers, RTC backup register and

backup SRAM), and Standby circuitry. This mode has the lowest current consumption,

which depends on the configuration of both backup SRAM (not available for

STM32F401x) and RTC.

•

VBAT mode:

–

The main digital supply (VDD) is turned off.

–

The circuit is supplied through VBAT pin which should be connected to an external

supply voltage (a battery or any other source).

This mode is used only when the main digital supply (VDD) is turned off and the VBAT

pin is connected to an external supply voltage (a battery or any other source). The VBAT

pin powers the Backup domain (RTC registers, RTC backup register and backup

SRAM).

For a further description of these low-power mode features and low-power technology of

STM32F4, you can refer to application note “How to achieve the lowest current consumption

with STM32F2xx” (AN3430) and to reference manuals RM0090 and RM0368, available

from the ST Website.

AN4365 Datasheet(PDF) 7 Page - STMicroelectronics

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