The power and clock management system automatically ensures maximum power efficiency.
The nRF9161 has three power modes - System Disabled, System ON and System OFF. The System ON and System OFF are internal (automatically handled by the device) and the System Disabled is external (driven by the ENABLE pin and overriding internal ones).
The core of the automatic power and clock management is the power management unit (PMU) illustrated in the following image.
When the device is powered and enabled, the PMU automatically tracks the power and clock resources required by the different components in the system. It then starts/stops and chooses operation modes in supply regulators and clock sources, without user interaction, to achieve the lowest power consumption possible.