VREGH behavior with low VDDH input

[scf]

When operating in high-voltage mode, the spec says that VREGH,DROP is at most 0.3V. What happens if VDDH falls below the programmed VDD output plus VREGH,DROP, for both the LDO and DC/DC modes?

For example, if VDD is programmed to be 3.3V, but VREGH is only 2.7V, what voltage will appear on VDD?

[ketiljo]

The regulator will have a drop of about 0.3 V. So the output will be 0.3 V lower than the input in this case. If you have 2.7 V in, you'll get 2.4 V on the VDD side.