The Evolution of the USB Standard
As mentioned earlier, the USB standard has continuously evolved since its inception to meet the demand for faster data transfer speeds and higher power delivery capabilities. The earliest USB standards offered data transfer rates of 1.5 Mbps (LS: Low Speed) and 12 Mbps (FS: Full Speed), but with the introduction of USB 2.0, speeds increased to 480 Mbps (HS: High Speed). Subsequently, with the release of USB 3.0, 3.1, and 3.2, speeds were further boosted to 5–20 Gbps (SS: SuperSpeed).
The latest USB4 uses Gen 3x2 lanes, enabling transfer speeds of up to 40 Gbps. In 2022, the USB Promoter Group announced the launch of the next-generation USB standard, “USB4 Version 2.0,” aimed at doubling the transfer speed to 80 Gbps.
*The USB Promoter Group is an independent organization primarily composed of Intel and Apple; it is distinct from the USB Implementers Forum (USB-IF).
On the other hand, growing demand for fast charging of smartphones and high-power delivery to peripherals led to the emergence of the USB PD (Power Delivery) standard, which utilizes the USB Type-C interface. Subsequently, the European Union mandated the use of USB Type-C charging ports to reduce electronic waste.
Additionally, the Thunderbolt 3 standard and its subsequent versions—developed jointly by Intel and Apple as the successor to FireWire—also adopt the USB Type-C interface.
*In addition to USB PD-compatible devices, if a connected device supports USB PD’s SPR (Standard Power Range), it can deliver up to 100W (20V/5A); if it supports USB PD’s EPR (Extended Power Range), it can deliver up to 240W (48V/5A). In addition, prior to the introduction of USB PD, the USB Battery Charging Specification 1.2 was released in 2010, with a maximum supply current of 1.5A.
Types of USB Cables and Connectors and How to Use Them Correctly
The shape of USB ports is defined by the USB standard; a single USB port can simultaneously transmit data and supply power to peripheral devices. USB is backward compatible, meaning devices can be connected as long as the connector shapes match. Data transfer speeds are also limited by the lower-end standard.
Connector shapes are classified into Type A, Type B, and Type C. Type B comes in standard, mini, and micro sizes (Type A also has mini and micro sizes, as well as mini-AB and micro-AB for OTG compatibility, but these sizes have been replaced by Type C and are therefore omitted).