4 ms·
USB 1.1/2.0 is required to deliver 100 mA per port, but may deliver up to 500 mA. Devices state their power requirements (in units of 1 or 2 mA, IIRC) during e
by ken 18y ago
USB 1.1/2.0 is required to deliver 100 mA per port, but may deliver up to 500 mA. Devices state their power requirements (in units of 1 or 2 mA, IIRC) during enumeration, which always runs at 100 mA, and the host computer says yea or nay.
And yes, the USB spec actually measures "power" in "milliamps".
- jrockway 18y agoAnd yes, the USB spec actually measures "power" in "milliamps". That's OK, since it's always the same constant factor (5) away from the real power.