I'm working on a prototype board which has multiple USB device connectors (e.g. the one for a microcontroller thing I'm communicating with, and a second one for JTAG).
Now I wonder how I should treat the VCC line, because I'd like to power the board from either USB connector.
Sure, I can put a Schottky diode in line with each VCC and call it a day. I don't want the voltage drop though. I power some things from 5V and on some USB hosts I already see voltages as low as 4.5V instead of 5V. Loosing another 0.3V or so would be critical.
Since I'm going to power the device from a single USB Hub anyway, would it be okay to just connect the two VCC lines? The only other option I can see now is to forget about USB power, leave VCC open and use an external power supply.