TM4C_PINMUX: TM4C123GE6PZ Using the internal clock to drive the RTC？

Hi，

RTC as part of Hibernation module, can be continuously powered by a separate backup battery (VBAT) when the main power supply (VDD) is off
VBAT Operation: The HIB (Hibernation) module, which houses the RTC, is designed to run from a secondary power source connected to the VBAT pin. This allows the RTC to keep track of time and retain data in dedicated memory registers even when the main VDD supply is powered down or lost.

Please refer to Tiva C Series TM4C123GE6PZ Microcontroller Data Sheet datasheet (Rev. E)

and TivaWare for C Series software library to access and configure the hibernation module and RTC features SW-TM4C

Thanks