I recommend you to use the schematics of the Mini-Breakout Board and the Arduino Expansion Board as reference:
- Intel® Edison Boards and Compute Modules — Intel® Edison Breakout Board Schematic
- Intel® Edison Boards — Arduino* Board Schematic
The Edison's power input corresponds to the VSYS pins (pins 2, 4, and 6). You can check in the schematics above where the VSYS pins are connected to.
Additionally, I recommend you to read the Intel® Edison Boards — Compute Module Hardware Guide. You will find details about the Edison module and how to power it properly.
I didn't know that the schematics for the breakout boards where avaliable, thanks for linking to those and the hardware guide! I'm surprised I haven't seen the guide before when researching Edison stuff, that's going to be a big help