01-25-2009, 04:50 AM
USB 1.1 and 2.0 provide +5VDC @ 500mA (2.5W) per port.
If you use an unpowered USB hub/splitter, then the total available power through all the hub ports is limited to the 5VDC@500mA supplied from the upstream port.
If the USB hub is powered, each port will supply +5VDC@500mA .
If the drive + case power requirements exceed 2.5W, a USB port will not provide sufficient power; you will need to provide external power for the case and drive.
If you use an unpowered USB hub/splitter, then the total available power through all the hub ports is limited to the 5VDC@500mA supplied from the upstream port.
If the USB hub is powered, each port will supply +5VDC@500mA .
If the drive + case power requirements exceed 2.5W, a USB port will not provide sufficient power; you will need to provide external power for the case and drive.