System ON is the default operation mode after power-on reset.
In System ON, all functional blocks, such as the CPU and peripherals, can be in an IDLE or RUN state depending on the configuration set by the software and the state of the executing application.
The power and clock management unit can switch the appropriate internal power domains on and off, depending on power requirements. A peripheral's power requirement is directly related to its activity level, which increases and decreases when specific tasks are triggered or events are generated.