Amazon Basics 3.0 USB-A Male to Micro USB Cable With Gold-Plated Connectors, 1.8 m, 6 Feet, Black

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The Type-B plug: This plug has a near square cross-section with the top exterior corners beveled. As part of a removable cable, it inserts into an upstream port on a device, such as a printer. On some devices, the Type-B receptacle has no data connections, being used solely for accepting power from the upstream device. This two-connector-type scheme (A/B) prevents a user from accidentally creating a loop. [9] [10]

Battery Charging v1.1 Spec and Adopters Agreement". USB.org. Archived from the original on 11 January 2021 . Retrieved 31 July 2019.Metz, Cade (25 February 2003). "The Great Interface-Off: FireWire Vs. USB2.0". PC Magazine. Archived from the original on 30 September 2007 . Retrieved 25 August 2007. Heron, Robert. "USB2.0 Versus FireWire". TechTV. Archived from the original on 29 September 2007 . Retrieved 25 August 2007. Battery Charging v1.2 Spec and Adopters Agreement". USB.org. Archived from the original on 31 July 2019 . Retrieved 31 July 2019. USB 3.2 Specification Language Usage Guidelines from USB-IF" (PDF). usb.org. 26 February 2019. Archived (PDF) from the original on 3 November 2021 . Retrieved 4 September 2019. USB 2.0 Specification". USB Implementers Forum. Archived from the original on 3 December 2017 . Retrieved 28 April 2019.

USB Promoter Group Announces USB4 Version 2.0 Specification defines delivering up to 80Gbps over USB Type-C" (PDF). USB On-The-Go (OTG) introduces the concept of a device performing both host and device roles. All current OTG devices are required to have one, and only one, USB connector: a Micro-AB receptacle. (In the past, before the development of Micro-USB, On-The-Go devices used Mini-AB receptacles.) Upstream USB connectors supply power at a nominal 5V DC via the V_BUS pin to downstream USB devices. Ravencraft, Jeff (19 November 2019). "USB DevDays 2019 – Branding Session" (PDF). USB Implementers Forum (Presentation). p.16. Archived from the original (PDF) on 22 March 2020 . Retrieved 22 March 2020.Voltage tolerance and limits [ edit ] Worst-case voltage drop topology of a USB 2.0 host to low-power device chain, at steady state USB runs with a 5 V power line, while FireWire supplies 12V and theoretically can supply up to 30V.

Several manufacturers offer external portable USB hard disk drives, or empty enclosures for disk drives. These offer performance comparable to internal drives, limited by the number and types of attached USB devices, and by the upper limit of the USB interface. Other competing standards for external drive connectivity include eSATA, ExpressCard, FireWire (IEEE 1394), and most recently Thunderbolt. USB signals are transmitted using differential signaling on twisted-pair data wires with 90 Ω ± 15% characteristic impedance. [93] USB 2.0 and earlier specifications define a single pair in half-duplex (HDx). USB 3.0 and later specifications define one dedicated pair for USB 2.0 compatibility and two or four pairs for data transfer: two pairs in full-duplex (FDx) for single lane variants require SuperSpeed connectors; four pairs in full-duplex for two lane (×2) variants require USB-C connectors. USB4 Gen 4 requires the use of all four pairs but allow for asymmetrical pairs configuration, [94] in this case one lane is used for the upstream data and the other three for the downstream data or vice-versa. USB4 Gen 4 use pulse amplitude modulation on 3 levels, providing a trit of information every baud transmitted, the transmission frequency of 12.8GHz translate to a transmission rate of 25.6 GBd [95] and the 11-bit–to–7-trit translation provides a theoretical maximum transmission speed just over 40.2 Gbit/s. [96] Operation mode Though most personal computers since early 2005 can boot from USB mass storage devices, USB is not intended as a primary bus for a computer's internal storage. However, USB has the advantage of allowing hot-swapping, making it useful for mobile peripherals, including drives of various kinds. PS/2 to USB Keyboard and Mouse Adapter". StarTech.com. Archived from the original on 12 November 2014 . Retrieved 21 May 2023. FireWire vs. USB2.0 – Bandwidth Tests". Archived from the original on 12 August 2007 . Retrieved 25 August 2007.Worst-case voltage drop topology of a USB 3. x host to device chain, at steady state. Note that under transient conditions the supply at the device can momentarily drop from 4.0V to 3.67V. Allowable current draw [ edit ] USB power standards The eSATA connector is a more robust SATA connector, intended for connection to external hard drives and SSDs. eSATA's transfer rate (up to 6Gbit/s) is similar to that of USB3.0 (up to 5Gbit/s) and USB3.1 (up to 10Gbit/s). A device connected by eSATA appears as an ordinary SATA device, giving both full performance and full compatibility associated with internal drives.

For a host providing power to devices, USB has a concept of the unit load. Any device may draw power of one unit, and devices may request more power in these discrete steps. It is not required that the host provide requested power, and a device may not draw more power than negotiated. At first, USB was considered a complement to FireWire ( IEEE 1394) technology, which was designed as a high-bandwidth serial bus that efficiently interconnects peripherals such as disk drives, audio interfaces, and video equipment. In the initial design, USB operated at a far lower data rate and used less sophisticated hardware. It was suitable for small peripherals such as keyboards and pointing devices.For a product developer, using USB requires the implementation of a complex protocol and implies an "intelligent" controller in the peripheral device. Developers of USB devices intended for public sale generally must obtain a USB ID, which requires that they pay a fee to the USB Implementers Forum (USB-IF). Developers of products that use the USB specification must sign an agreement with the USB-IF. Use of the USB logos on the product requires annual fees and membership in the organization. [12] History [ edit ] The basic USB trident logo [15] USB logo on the head of a standard Type-A (Standard-A) plug The USB3.2 specification added a second lane to the Enhanced SuperSpeed System besides other enhancements, so that SuperSpeedPlus USB system part implements the Gen 1×2, Gen 2×1 and Gen 2× operation modes. The SuperSpeed USB part of the system however still implements the one-lane Gen 1×1 operation mode. Therefore, two-lane operations, namely USB3.2 Gen1× 2(10 Gbit/s) and Gen2× 2(20 Gbit/s), are only possible with Full-Featured USB-C Fabrics. [7] As of 2023, [update] they are somewhat rarely implemented; Intel, however, includes them in its 11th generation SoC processor models. On the other hand, USB3.2 Gen1(x1) (5 Gbit/s) and Gen2(x1) (10 Gbit/s) has been quite common for some years. Full Speed USB Maximum Theoretical Throughput". Microchip Technology Incorporated. 23 March 2021. Archived from the original on 26 March 2021 . Retrieved 23 March 2021. The limit to device power draw is stated in terms of a unit load which is 100mA for USB 2.0, or 150mA for SuperSpeed (i.e. USB 3. x) devices. Low-power devices may draw at most 1 unit load, and all devices must act as low-power devices before they are configured. A high-powered device must be configured, after which it may draw up to 5 unit loads (500mA), or 6 unit loads (900mA) for SuperSpeed devices, as specified in its configuration because the maximum power may not always be available from the upstream port. [43] [44] [45] [46] Parameter Values". Battery Charging Specification, Revision 1.2. USB Implementers Forum. 7 December 2010. p.45. Archived from the original on 28 March 2016 . Retrieved 29 March 2016.