Agreement on Mobile phone Standard Charger" (Press release). GSM World. Archived from the original on 17 February 2009. Universal Serial Bus Revision 3.0 Specification, Sections 3.1.1.1 and 5.3.1.3". Usb.org. Archived from the original (ZIP) on 19 May 2014 . Retrieved 28 April 2019. The different A and B plugs prevent accidentally connecting two power sources. However, some of this directed topology is lost with the advent of multi-purpose USB connections (such as USB On-The-Go in smartphones, and USB-powered Wi-Fi routers), which require A-to-A, B-to-B, and sometimes Y/splitter cables. See the USB On-The-Go connectors section below for a more detailed summary description. 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] a b "Deprecation of the Mini-A and Mini-AB Connectors" (PDF) (Press release). USB Implementers Forum. 27 May 2007. Archived from the original (PDF) on 6 March 2009 . Retrieved 13 January 2009.

Lam, Crystal; Liu, Harry (October 22, 2007). "How to conform to China's new mobile phone interface standards". Wireless Net DesignLine. Archived from the original on May 14, 2014 . Retrieved June 22, 2010.

Mini-USB connectors were introduced together with USB 2.0 in April 2000, for use with smaller devices such as digital cameras, smartphones, and tablet computers. The Mini-A connector and the Mini-AB receptacle connector have been deprecated since May 2007. [11] Mini-B connectors are still supported, but are not On-The-Go-compliant; [12] the Mini-B USB connector was standard for transferring data to and from the early smartphones and PDAs. Both Mini-A and Mini-B plugs are approximately 3 by 7mm (0.12 by 0.28in). The Mini-AB receptacle accepts either a Mini-A or Mini-B plug. Edison's revenge". The Economist. October 19, 2013. Archived from the original on October 22, 2013 . Retrieved October 23, 2013. They are commonly found on rechargeable technologies and smaller peripherals. Micro-USB B, being the smaller of the two, is often seen on newer devices, while the slightly bigger USB Mini-b is now less widely used. USB Type-C Revision 1.0" (PDF). USB 3.0 Promoter Group. March 1, 2021. Archived (PDF) from the original on November 3, 2021 . Retrieved November 3, 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]

Connector properties [ edit ] Non-standard "USB extension cable", plug on the left, receptacle on the right. (USB does not allow extension cables. Non-standard cables may work but cannot be presumed reliable.) Nice Micro-USB adapter Apple, now sell it everywhere", Giga om, 5 October 2011, archived from the original on 26 August 2012USB ECN USB 2.0 VBUS Max Limit". USB-IF. November 3, 2021. Archived from the original on November 3, 2021 . Retrieved November 3, 2021. I have the drive plugged in but I cannot find the drive in "My Computer", why?". hitachigst.com. Archived from the original on 15 February 2011 . Retrieved 30 March 2012. The Chinese technical standard: "YD/T 1591-2006, Technical Requirements and Test Method of Charger and Interface for Mobile Telecommunication Terminal Equipment" (PDF). Dian yuan (in Chinese). Archived from the original (PDF) on 15 May 2011. The USB Power Delivery specification revision3.0 defines an optional Programmable Power Supply (PPS) protocol that allows granular control over V BUS power, allowing a range of 3.3 to 21 V in 20mV steps to facilitate constant-current or constant-voltage charging. Revision 3.0 also adds extended configuration messages and fast role swap and deprecates the BFSK protocol. [57] [68] [69] The Certified USB Fast Charger logo for USB Type-C charging ports