DocID018933 Rev 2

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AN3413

Application description

17

performed again.

1.6

Low power modes

The low power modes used in this application are listed below. The microcontroller can be

woken up from any power saving mode by an external wake-up event generated by counter

U3.

•

Sleep mode: The CPU is stopped, the peripherals kept running. The system is clocked

by the MSI oscillator at a frequency of 4 MHz.

•

Low power run mode: The CPU and some of the peripherals are running. During Low

power run mode, the code is executed from RAM and the CPU is clocked at a

frequency of 32 kHz by the MSI oscillator. Flash and data EEPROM are stopped and

the voltage regulator is configured in Ultra low power mode.

•

Low power sleep mode: The CPU is stopped. The system clock frequency is reduced

to 32 kHz. Flash and Data EEPROM are in power down mode and the voltage

regulator is configured in Ultra low power mode.

•

Stop mode: The Core is in Deepsleep mode, Flash, Data EEPROM and all clocks

except LSE are in power down mode. All peripherals except the LCD are disabled. The

voltage regulator is in low power mode.

•

Stop mode without LCD: This is the same as Stop mode except that the LCD

controller is also disabled in this case.

•

Standby mode: This is the deepest low power mode. The voltage regulator is

disabled. Core, peripherals, RAM, Flash and Data EEPROM are powered off. Power is

maintained for the RTC registers, backup registers and standby circuitry. Device wake-

up is done by an external wake-up event, generating a system reset.

For further information, please refer to STM32L15x reference manual (RM0038) where you

can find more details about all the available configurations for each STM32L15x low power

mode.