# USB 2 Standard-A receptacle > a legacy USB receptacle that preceded USB-C (“A” indicating the host end) **Wikidata**: [Q50289699](https://www.wikidata.org/wiki/Q50289699) **Source**: https://4ort.xyz/entity/usb-2-standard-a-receptacle ## Summary The USB 2 Standard-A receptacle is a legacy USB host-end connector introduced with USB 2.0, characterized by its rectangular shape and replaced by USB-C. It facilitated data transfer and power delivery for USB 1–2 devices before being superseded. ## Key Facts - **Official Name**: USB 2.0 Standard-A receptacle (per USB.org documentation, 2025-04-19). - **Pin Configuration**: Four pins: VBUS (power, red), D− (white), D+ (green), and GND (ground, black). - **Physical Design**: Rectangular receptacle with internal pins, distinct from USB-C’s reversible oval shape. - **Compatibility**: Connects with USB 2 Standard-A plugs and USB 3 Standard-A plugs. - **Legacy Status**: Preceded USB-C; replaced by USB-C receptacles in modern devices. - **Classifications**: Instance of USB 2 Standard-A connector, USB 2 Standard receptacle, USB 2 Type-A receptacle, and USB Standard-A receptacle. - **Aliases**: USB Hi-Speed Standard-A receptacle, USB 1.1 Standard-A receptacle, Standard USB 2.0 Type-A receptacle, etc. - **Different From**: USB 2 Standard-A plug (opposite connector), USB 2 Standard-B receptacle, USB 3 Standard-A receptacle. ## FAQs ### Q: What devices commonly used USB 2 Standard-A receptacles? A: They were standard on hosts like computers, hubs, and chargers for USB 1–2 peripherals (e.g., keyboards, mice, flash drives) before USB-C adoption. ### Q: How does USB 2 Standard-A differ from USB 3 Standard-A? A: USB 2 Standard-A supports USB 1–2 speeds (up to 480 Mbps), while USB 3 Standard-A adds extra pins for 5 Gbps speeds but retains the same physical shape. ### Q: Why was USB 2 Standard-A replaced by USB-C? A: USB-C offers reversibility, higher power delivery, faster data speeds (USB 3.2/4), and a smaller form factor, addressing limitations of the legacy Standard-A design. ### Q: Can USB 2 Standard-A receptacles charge modern devices? A: Yes, they provide power (typically 5V) but lack USB-C’s advanced power negotiation, limiting charging speed and compatibility with fast-charging standards. ## Why It Matters The USB 2 Standard-A receptacle standardized peripheral connectivity for over a decade, enabling ubiquitous plug-and-play functionality across billions of devices. Its simple, cost-effective design democratized high-speed data transfer and power delivery, fueling the growth of consumer electronics. Though now legacy, it remains critical for maintaining compatibility with older hardware and serves as a benchmark for connector evolution. Its replacement by USB-C underscores the industry’s shift toward faster, more versatile interfaces, yet its widespread adoption established USB as the dominant global standard for device interconnectivity. ## Notable For - **Pioneered Host-End Standardization**: Defined the "A" designation for host devices, distinguishing it from peripheral connectors (e.g., Type-B). - **Ubiquitous Legacy Adoption**: Integrated into virtually all PCs, laptops, and chargers from the early 2000s to 2010s. - **Simplified User Experience**: Enabled intuitive, non-reversible plug orientation that reduced user errors during connection. - **Power Delivery Foundation**: Established VBUS/GND pinout for 5V power, later expanded in USB-C for higher wattage. - **Longevity**: Remained the dominant USB host connector for over 15 years before USB-C’s emergence. ## Body ### Physical Design The USB 2 Standard-A receptacle is a rectangular, internal-mounted connector with four pins arranged in a single row. Its trapezoidal opening ensures directional insertion, preventing incorrect connections. Dimensions follow USB specifications, with pin spacing standardized for compatibility across devices. ### Pinout Specifications - **VBUS (Pin 1)**: Red wire, supplies 5V power (up to 5A in legacy implementations). - **D− (Pin 2)**: White wire, carries differential data for USB 1–2 signaling. - **D+ (Pin 3)**: Green wire, paired with D− for bidirectional data transfer. - **GND (Pin 4)**: Black wire, serves as the ground reference. Pin assignments align with USB 2.0 specifications, ensuring backward compatibility with USB 1.1/1.0 devices. Color coding aids assembly but is not user-facing. ### Evolution and Replacement Introduced with USB 2.0 in 2000, it succeeded USB 1.x receptacles while maintaining physical compatibility. USB 3.0 added extra pins to Standard-A receptacles for 5 Gbps speeds but retained the outer dimensions. The receptacle was fully replaced by USB-C in the 2010s due to USB-C’s reversibility, higher bandwidth (up to 40 Gbps), and power delivery capabilities (up to 240W). ### Compatibility and Usage - **Connects With**: USB 2 Standard-A plugs (e.g., cables for printers) and USB 3 Standard-A plugs (backward-compatible). - **Opposite Connector**: USB 2 Standard-A plug (peripheral-end). - **Legacy Support**: Modern devices often include USB 2 Standard-A receptacles via adapters or legacy ports for older peripherals. ### Technical Classification - **Instance Of**: USB 2 Standard-A connector, USB 2 Standard receptacle, USB 2 Type-A receptacle, USB Standard-A receptacle. - **Has Part**: Lead (internal wiring/contacts). - **Different From**: USB 2 Standard-A plug, USB 2 Standard-B receptacle (peripheral end), USB 3 Standard-A receptacle (with extra pins). ### Documentation and References - **Official Specification**: USB 2.0 Specification (usb.org). - **Legacy Cable Guidelines**: USB 3.1 Legacy Cable and Connector Revision 1.0. - **Visual Resources**: Schematics and pinout diagrams available on Wikimedia Commons. ## References 1. [Source](https://www.usb.org/document-library/usb-31-legacy-cable-and-connector-revision-10) 2. [Source](https://www.usb.org/document-library/usb-20-specification)