System ON mode

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.

In System ON mode, the system can reside in one of the two sub-power modes when the CPU and all peripherals are in an IDLE state.

The sub-power modes are the following:

• Constant Latency
• Low-power

In Constant Latency mode, the CPU wakeup latency and the PPI task response are constant and kept at a minimum. This is secured by forcing a set of basic resources to be turned on while in sleep mode. Constant and predictable latency increases power consumption. Constant Latency mode is selected by triggering the task CONSTLAT.

In Low-power mode, the automatic power management system described in System ON mode ensures that the most efficient supply option is chosen to save power. The lowest possible power consumption comes at a cost of a varying CPU wakeup latency and PPI task response. Low-power mode is selected by triggering the task LOWPWR.

When the system enters System ON mode, it is in the sub-power mode Low-power by default.