STM8L052R8 datasheet(13/109 Pages) STMICROELECTRONICS

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STM8L052R8

Functional overview

Doc ID023337 Rev 2

13/109

3.1

Low power modes

The high density value line STM8L05xxx devices support five low power modes to achieve

the best compromise between low power consumption, short startup time and available

wakeup sources:

●

Wait mode: The CPU clock is stopped, but selected peripherals keep running. An

internal or external interrupt, event or a Reset can be used to exit the microcontroller

from Wait mode (WFE or WFI mode).

●

Low power run mode: The CPU and the selected peripherals are running. Execution

is done from RAM with a low speed oscillator (LSI or LSE). Flash memory and data

EEPROM are stopped and the voltage regulator is configured in ultra low power mode.

The microcontroller enters Low power run mode by software and can exit from this

mode by software or by a reset.

All interrupts must be masked. They cannot be used to exit the microcontroller from this

mode.

●

Low power wait mode: This mode is entered when executing a Wait for event in Low

power run mode. It is similar to Low power run mode except that the CPU clock is

stopped. The wakeup from this mode is triggered by a Reset or by an internal or

external event (peripheral event generated by the timers, serial interfaces, DMA

controller (DMA1) and I/O ports). When the wakeup is triggered by an event, the

system goes back to Low power run mode.

All interrupts must be masked. They cannot be used to exit the microcontroller from this

mode.

●

Active-halt mode: CPU and peripheral clocks are stopped, except RTC. The wakeup

can be triggered by RTC interrupts, external interrupts or reset.

●

Halt mode: CPU and peripheral clocks are stopped, the device remains powered on.

The wakeup is triggered by an external interrupt or reset. A few peripherals have also a

wakeup from Halt capability. Switching off the internal reference voltage reduces power

consumption. Through software configuration it is also possible to wake up the device

without waiting for the internal reference voltage wakeup time to have a fast wakeup

time of 5 µs.

STM8L052R8 Datasheet(PDF) 13 Page - STMicroelectronics