All power-managment functionality is handled by the TI-RTOS power driver and are used by the peripheral drivers (e.g. UART, SPI, I2C, etc..). Applications can prevent, if they choose, the CC26x2 from entering low power modes by setting a power constraint.
With Z-Stack applications, the power contraint is set in
POWER_SAVINGS preprocessor symbol. When defined,
enabled, the device enters and exits sleep as required for Z-Stack events,
peripheral events, application timers, and so forth. When undefined, the
device stays awake.
More information on power-management functionality, including the API and a sample use case for a custom UART driver, can be found in the TI-RTOS Power Management for CC26x2 included in the TI-RTOS install. These APIs are required only when using a custom driver.
Also see Measuring Bluetooth Smart Power Consumption (SWRA478) for steps to analyze the system power consumption and battery life.