AN2945

System features

Doc ID 15468

13/18

3.5

Low power

On top of the core’s intrinsic low power modes, both the STM8S and STM32 devices are

able to reduce the overall consumption at system-on-chip level.

The power consumption in the Run and Wait modes can be reduced by one of the following

means:

●

Slowing down the system clocks: the consumption can thus be adjusted according to

the performance required by the application. This is done using the prescalers included

in the clock controller.

●

Gating the clocks of the peripherals when they are not used to minimize the dynamic

consumption related to the clock tree switching activity.

The two products embed regulators to supply the internal logic at 1.8 V. These regulators

have a significant operating current in Run mode (a few tens of µA) where they are able to

deliver currents in the mA or tens of mA range. In order to further reduce consumption, it is

possible to configure the regulator in low power mode, and minimize its quiescent

consumption, when the current necessary to supply the logic is in the µA range, typically

during the Halt or Stop mode. This mode offers the lowest consumption, with a wakeup time

slightly longer than the configuration using the regulator in Run mode.