PoweredUSB uses a more complex connector than standard USB, maintaining the standard connector of USB 1.x and USB 2.0 interface for data communications and adding a second connector for power. Physically, it is essentially two connectors stacked such that the bottom connector accepts a standard USB plug and the top connector takes a power plug. The implementation allows a choice of three different voltages, providing power at 5
V (30
W), 12 V (72 W), 24 V (144 W) as well as a custom voltage. Some implementations provide 19 V or 25 V. The connectors are able to operate at up to 6
A (3 A per pin) peak, but according to the specification, hosts are required to provide a minimum sustainable
rms current of 1.5 A at 5 V (7.5 W) or 12 V (18 W), or 2.3 A at 24 V (55.2 W), only. For comparison, a standard USB 1.x and 2.0 hosts supplies 5 V at up to 0.5 A (2.5 W).
USB 3.0 supplies 5 V at up to 0.9 A (4.5 W) whereas hosts conformant to the
USB Battery Charging Specification can deliver up to 1.5 A (7.5 W). As each PoweredUSB plug provides one of three voltages, the plugs come keyed in three versions, so that they will only accept connections from devices requiring that version's voltage. The connectors can be color-coded for different voltages: Gray (
Pantone Cool Gray 1C) (sometimes also "nature" or yellow) for 5 V, blue-green (Pantone Teal 3262C) for 12 V, red (Pantone Red 032C) for 24 V/25 V and violet for 19 V; alternatively, any voltages higher than 5 V can be indicated by a black connector color. The connectors, available from various manufacturers, provide an auto-locking facility to reduce the risk of accidental power failures. Special provisions for
hot-plugging are recommended, but optional. The red 24 volt plugs should never be plugged in or removed with the unit powered on. ==Future==