WEBENCH® Tools/CC2640R2F: Battery on CC2640R2F

Part Number:CC2640R2F

Tool/software: WEBENCH® Design Tools

Hi,

I would to use a battery to keep active the Real Time Clock when the power goes off.

Is there on CC2640 the pin to allow supply only the RTC function with the battery and other CC2640 function with power supply? Or I need to develop a protectiom circuit to switch from power supply to battry when the power goes off and to keep the CC2640 in stendby mode.

Thanks

Giuseppe.