USB/Connector/Ref/USB-A

• USB-A Connector Reference

  • Visual Reference

    • 
    • Photo: André Karwath, CC BY-SA 2.5, via Wikimedia Commons

  • Overview

    • Standard USB Type-A connector, the most common USB connector type
    • Introduced with USB 1.0 specification (1996)
    • Rectangular shape with non-reversible design (must be inserted in correct orientation)
    • Primarily used on host devices (computers, hubs, chargers) and some peripherals

  • Physical Specifications

    • Dimensions:
      • Width: 12.0 mm
      • Height: 4.5 mm
      • Length: Variable (depends on plug design)
    • Pin Count:
      • 4 pins (USB 1.0, 1.1, 2.0)
      • 9 pins (USB 3.0 and later)
    • Orientation: Non-reversible (must be inserted in correct orientation)
    • Gender: Male connector (plugs into host/receptacle)
    • Color Coding:
      • Black or white interior: USB 2.0
      • Blue interior: USB 3.0 and later

  • Technical Specifications

    • USB Versions Supported: USB 1.0, 1.1, 2.0, 3.0, 3.1, 3.2
    • Data Transfer Rates:
      • USB 1.0/1.1: 1.5 Mbps (Low-Speed) / 12 Mbps (Full-Speed)
      • USB 2.0: 480 Mbps (High-Speed)
      • USB 3.0 (3.1 Gen 1, 3.2 Gen 1): 5 Gbps (SuperSpeed)
      • USB 3.1 Gen 2 (3.2 Gen 2): 10 Gbps (SuperSpeed+)
      • USB 3.2 Gen 2x2: 20 Gbps (requires USB-C on other end)
    • Power Delivery:
      • USB 1.0/1.1/2.0: Up to 2.5W (5V @ 500mA)
      • USB 3.0 and later: Up to 4.5W (5V @ 900mA)

  • Pin Configuration

    • USB 2.0 (4 pins)

      • Pin 1: VCC (+5V) - Power supply
      • Pin 2: D- (Data -) - Differential data pair negative
      • Pin 3: D+ (Data +) - Differential data pair positive
      • Pin 4: GND (Ground) - Ground reference

    • USB 3.0+ (9 pins)

      • Pins 1-4: Same as USB 2.0
      • Pin 5: StdA_SSRX- (SuperSpeed receive negative)
      • Pin 6: StdA_SSRX+ (SuperSpeed receive positive)
      • Pin 7: GND_DRAIN (Ground for shielding)
      • Pin 8: StdA_SSTX- (SuperSpeed transmit negative)
      • Pin 9: StdA_SSTX+ (SuperSpeed transmit positive)

  • Compatibility

    • Compatible Connectors:
      • USB/Connector/Ref/USB-B (standard pairing)
      • USB/Connector/Ref/USB-B Mini (via cable)
      • USB/Connector/Ref/USB-B Micro (via cable)
      • USB/Connector/Ref/USB-C (via adapter or cable)
    • Backward Compatibility:
      • USB 3.0+ connectors are backward compatible with USB 2.0 devices
      • USB 2.0 devices will operate at USB 2.0 speeds when connected to USB 3.0+ ports

  • Common Use Cases

    • Host devices (computers, laptops, tablets)
    • USB hubs and docking stations
    • USB flash drives and external storage
    • Keyboard and mouse connections
    • Printer and scanner connections
    • Charging adapters and power banks
    • Audio interfaces and MIDI controllers

  • Variants

    • USB-A 2.0

      • 4-pin configuration
      • Black or white interior
      • Supports up to USB 2.0 speeds (480 Mbps)

    • USB-A 3.0 (USB 3.1 Gen 1, USB 3.2 Gen 1)

      • 9-pin configuration
      • Blue interior (standard color coding)
      • Supports up to 5 Gbps (SuperSpeed)

    • USB-A 3.1 Gen 2 (USB 3.2 Gen 2)

      • 9-pin configuration
      • Blue or teal interior
      • Supports up to 10 Gbps (SuperSpeed+)

  • Visual Identification

    • Rectangular shape with flat bottom and slightly rounded top
    • Hollow interior with visible pins
    • USB 3.0+ versions have additional pins visible inside
    • Color coding: Blue interior indicates USB 3.0 or later

  • Standards

    • Defined in USB-IF specifications
    • USB 1.0/1.1: USB 1.0 specification (1996)
    • USB 2.0: USB 2.0 specification (2000)
    • USB 3.0+: USB 3.0 and subsequent specifications

  • Related References

    • USB/Connector/Ref/Index
    • USB/Connector/Ref/USB-B
    • USB/Connector/Ref/USB-C
    • USB/Connector/Ref/USB-B Micro