I’m designing a PoE PD interface with the MP8007H and adapter input of 24 V, but if I could go up to 48 V it would be perfect.
The thing is, the divider network that works for 24 V will get a VDD-VAUX voltage > 6.5 V for 48 V input. The datasheet states that the current through the AUX pin should be limited (that’s ok using a limiting resistor RT).
I’m trying to understand if the voltage of the AUX pin can exceed 6.5V with respect to VDD.
You can not exceed VDD with VAUX. If you look a the absolute maximum rating table on page three you can see the exact range of voltage allowed relative to VDD. The reason for this is likely protection, as any transients that would damage the pin can get dissipated into the power supply.