All power-management functionality is handled by the TI-RTOS power driver and is used by the peripheral drivers (e.g. UART, SPI, I2C, etc..). Applications can prevent, if they choose, the CC13x2 or CC26x2 from entering low power modes by setting a power constraint.
With Z-Stack applications, the power constraint is set in
for End Device types by defining the
RFD_RCVC_ALWAYS_ON preprocessor symbol
ZG_BUILD_ENDDEVICE_TYPE defined, the device enters and
exits sleep as required for Z-Stack events, peripheral events, application
timers, and so forth. Coordinator and Router Zigbee device types must always stay
awake to properly route packets.
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 CC13x2 or CC26x2 included in the SimpleLink CC13x2 / 26x2 SDK install. These APIs are required only when using a custom driver.
Also see Z-Stack End Device Power Consumption Measurement (SWRA625) for steps to analyze the system power consumption and battery life.