3.6.1 CVDDRTC Must be Always Supplied - [0.998 V - 1.43 V]
CVDDRTC MUST NOT be supplied by any on-chip LDO outputs
CVDDRTC voltage can be different to CVDD (core supply)
CVDDRTC can be supplied through a resistor divider or through diode(s) with forward voltage drop to take 1.8 V or 3.3 V to a voltage within the range [0.998 - 1.43V] (inefficient but cheap)
Consider max and min currents into CVDDRTC supply as well as max and min CVDDRTC voltages when sizing resistors
Typical max CVDDRTC current = 0.02 mA @ 1.3 V
Resistor divider values calculated to supply CVDDRTC with approximately 1.3 V from 3.3 V for CVDDRTC current of 0 mA to 0.05 mA: Rtop = 10k, Rbot = 6.5k
If RTC is not used, RTC_XI must be tied to CVDDRTC