I'm going to design a board with an embedded USB Host connector (managed by Atmel SAM D21 MCU).
I will use that connection only for data communication with a smartphone or a pendrive. I don't need to recharge the battery of the smartphone. Of course, I need to supply the pendrive.
On my board I have to generate a +5V rail only for the USB, but I don't know what is its requirement. Could I use a 100mA regulator? Should I have a 500mA positive +5V rail?