The CC6UL Hardware Reference Manual describes an "undervoltage detection" without mentioning a specific undervoltage threshold. The PMIC data sheet describes a change from "ON" to "Coin Cell Mode" at an undervoltage threshold UVDET (falling 2.5V) and a LOWVINI interrupt at 2.70V.
As mentioned in question "[CC6UL]: 3.3V input voltage for VSYS and VSYS2":
"The minimum input voltage documented in the PMIC datasheet is 2.8V, but this input voltage is not enough for powering the whole CC6UL SOM".
Is there a CC6UL specified VSYS resp. VSYS2 voltage level at which the SoM will go into coincell mode? (front LDO used)