I really like the BeagleBone form factor and configuration. I think
the BeagleBone would be a lot more attractive if there was some 5v
power left from the USB connection to power "cape/daughterboard"
circuits. The reference manual states that for this condition, there
is NO power to the expansion header. Well something to consider for
BeagleBone 2.0 or BeagleBone-lite.
The limit is 500mA. There is some power available in the form of the 3.3V rail, so it isn’t like there is no power at all. All left over power from the USB is indeed connected to the expansion header via the SYS_5V rail. You can refer to the schematic for More information on this.
It all depends on how much power you use elsewhere on the board, such as Ethernet and if you have something plugged into the USB connector itself and how much power is used there.
For example, you can run a BeagleBone with a DVID cape on it all from USB.
Gerald
Just as a clarification. The statement in the SRM is about the 5VDC rail. That is the 5VDC input rail from the power jack. If you design a cape to only use that rail, meaning it needs more power, then under USB the power only mode, it will not be there. BUT, the 5VDC from the USB is provided on the expansion header via the SYS_5V pin.
Gerald