I am designing a device to be powered off of USB. How do I change the current limit of the USB port from 100mA to 500mA? Is this done by command from my device to the computer? I only need the USB for power, so I don't want to have to build a driver in my device.
Standard USB hub ports can provide from the typical 500mA[2.5 Watts] of current, only 100mA from non-hub ports. USB 3.0 & USB On-The-Go 1800mA[9.0W] (for dedicated battery charging, 1500mA[7.5W] Full bandwidth or 900mA[4.5W] High Bandwidth), while FireWire can in theory supply up to 60 watts of power, although 10 to 20 watts is more typical.
Bus-powered hubs: Draw Max 100 mA at power up and 500 mA normally.
Self-powered hubs: Draw Max 100 mA, must supply 500 mA to each port.
Low power, bus-powered functions: Draw Max 100 mA.
High power, bus-powered functions: Self-powered hubs: Draw Max 100 mA, must supply 500 mA to each port.
Self-powered functions: Draw Max 100 mA.
Suspended device: Max 0.5 mA