What module does the VBAT pin primarily supply power to?

[a_ziliu]

The VBAT pin primarily supplies power to the RTC module and external low-speed oscillator (LXT), as shown below:

If the RTC module is not supplied power by VBAT, its status is uncertain, causing power consumption and affecting the performance of standby power. LXT cannot be used as well because there is no power supply. When calling CLK_WaitClockReady to check if the LXT function is stable during programming, it will get stuck and cannot continue.