Using Altium, one has the option to split schematic components into multiple parts. The examples given within the Altium documentation split chips with multiple discrete components in them, but I have also seen others split large ICs or MCUs into multiple parts. The image below shows how this applies to a small MCU, with both a part for power, and a part for "everything else":
I'm not aware of any standards (like you might have for electrical schematics for example) for PCB schematics, but are there any good guidelines for how/where it is appropriate to split large devices?
In a board I'm currently working on, we plan to use this 8 way ethernet switch chip. It's got 208 pins; ~70 of these are power pins and ~30 are factory test pins, neither of which do I need/want near my (slightly more complex) signalling circuitry. There are also chip config pins that again, don't necessarily group with the main switching function of the chip. The example schematics for the eval board include the chip drawn pin for pin which I don't like personally, but is this the best way to do it?
My current thinking is to have a "switch" part, which includes all the data and LED lines for the 8 ports, a "power" part with all the different VCCs and GNDs, and a third part with switch configuration pins and factory test pins. Can anyone suggest flaws with this method? Does it go against any "best practice" type rules?