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This section describes the power distribution model of USB that existed before Power-Delivery (USB-PD). On devices that do not use PD, USB provides up to 4.5 W through Type-A and Type-B connectors, and up to 15 W through USB-C. All pre-PD USB power is provided at 5 V. For a host providing power to devices, USB has a concept of the unit load ...
The written USB 3.0 specification was released by Intel and its partners in August 2008. The first USB 3.0 controller chips were sampled by NEC in May 2009, [4] and the first products using the USB 3.0 specification arrived in January 2010. [5] USB 3.0 connectors are generally backward compatible, but include new wiring and full-duplex operation.
Note the five additional pins on the underside of the tongue of the USB 3.0 port. Additional power for multiple ports on a laptop PC may be obtained in the following ways: Some ExpressCard-to-USB 3.0 adapters may connect by a cable to an additional USB 2.0 port on the computer, which supplies additional power.
To allow for voltage drops, the voltage at the host port, hub port, and device are specified to be at least 4.75 V, 4.4 V, and 4.35 V respectively by USB 2.0 for low-power devices, [a] but must be at least 4.75 V at all locations for high-power [b] devices (however, high-power devices are required to operate as a low-powered device so that they ...
The Type-C specification does not name specific DP speeds that it considers supported for passive cables where support is optional for active cables. The USB-C presentation on DP Alt mode [47] calls out passive full-featured USB-C cables for their DisplayPort support and headroom for future DP speed increases. HBR3 was the highest available DP ...
Because the USB port connectors on a computer housing are often closely spaced, plugging a flash drive into a USB port may block an adjacent port. Such devices may carry the USB logo only if sold with a separate extension cable. Such cables are USB-compatible but do not conform to the USB standard. [35] [36]
The USB OTG and Embedded Host Supplement to the USB 2.0 specification introduced three new communication protocols: . Attach Detection Protocol (ADP): Allows an OTG device, embedded host or USB device to determine attachment status in the absence of power on the USB bus, enabling both insertion-based behavior and the capability to display attachment status.
A four-port "long cable" "external box" USB hub A four-port "compact design" USB hub: upstream and downstream ports shown. A USB hub is a device that expands a single Universal Serial Bus (USB) port into several so that there are more ports available to connect devices to a host system, similar to a power strip.