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USB supplies bus power across VBUS and GND at a nominal voltage 5 V ± 5%, at supply, to power USB devices. * o: s6 p6 e: Z0 s3 f! r
Power is sourced solely from upstream devices or hosts, and is consumed solely by downstream devices.
& ~( e/ O* d# lUSB provides for various voltage drops and losses in providing bus power.
& {6 }1 ~% B% X: e5 r& ` SAs such, the voltage at the hub port is specified to be in the range 5.00 +0.25 / −0.60 V by USB 2.0, and 5.00 +0.25 / −0.55 V by USB 3.0. + P9 a& ?) F3 L: J
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Normal USB port:$ }$ v ~% o* i
5.0 +0.25 / -0.25 V5 p" [; M" `9 F
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Hub port:+ T8 i6 q. W% H
USB 2.0: 5.0 +0.25 / -0.6 V6 E0 S& X3 A$ @
USB 3.0: 5.0 +0.25 / -0.55 V |
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