I'm going to build a benchtop PSU from an ATX PSU, and I would like to add a USB charging port on it. It should be able to power an Arduino or charge my (non-Apple) phone. (I know Apple devices require additional circuits, but I don't own any so I don't bother with that.)
Since USB uses +5V I could directly connect the +5V of the female USB connector to +5V on the ATX, and USB GND to ATX +0V, leaving the data lines unconnected.
Is this a good idea? Does this allow devices to draw as much current as they need (like a USB phone charger), or are they limited to 500 mA (official USB max current) or even only 100 mA (USB initial max current)?