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 network core's CPU and peripherals can be in IDLE state, RUN state, or Force-OFF mode (see Force-OFF mode).
The PMU can switch the appropriate internal power sources 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.
Voltage and frequency scaling
nRF5340 automatically adjusts the internal voltages to optimize power efficiency.
Some configuration options request a higher internal voltage, which is seen as an increase in power consumption. These configurations are the following:
- Setting the frequency of the application core's clock to 128 MHz, see Application core frequency scaling. Increased power consumption in this mode is also observed when the CPU is sleeping, such as after executing the WFI (wait for interrupt) or WFE (wait for event) instructions.
Power consumption during System ON with CPU and peripherals in IDLE state sleep is reduced by configuring the application core's clock to 64 MHz before entering CPU sleep.
- Using QSPI with 96 MHz clock frequency
- Using the USB peripheral
- When debugging
- Requesting additional voltage on the VREGRADIO supply using VREQCTRL — Voltage request control