# USB 3 Micro-A plug > a legacy USB plug that preceded USB-C (“A” indicating the host end) **Wikidata**: [Q133458745](https://www.wikidata.org/wiki/Q133458745) **Source**: https://4ort.xyz/entity/usb-3-micro-a-plug ## Summary The USB 3 Micro-A plug is a legacy USB connector that served as the host end ("A") of a cable connection prior to the standardization of USB-C. Officially designated as the USB 3.1 Micro-A plug, it is identifiable by its white insulator color and a 10-pin configuration designed to support high-speed data transfer. It has been effectively replaced in modern devices by the reversible USB-C plug. ## Key Facts * **Official Name:** USB 3.1 Micro-A plug. * **Classification:** It is an instance of a USB 3 Micro plug, a USB 3 Type-A connector, and a USB Micro-A plug. * **Successor:** The connector has been replaced by the USB-C plug. * **Compatibility:** It connects with a USB 3 Micro-AB receptacle. * **Pin Configuration:** The plug features 10 leads (pins), a significant increase from its USB 2.0 predecessors. * **Distinct From:** It is distinct from the USB 3 Standard-A plug, the USB 2 Micro-A plug, and the USB 3 Micro-B plug. * **Standards Body:** Maintained by the USB Implementers Forum. * **Insulator Color:** The standard requires a white insulator color. ## FAQs ### Q: What is the difference between a USB 3 Micro-A plug and a USB 2 Micro-A plug? A: While both act as host-end connectors, the USB 3 Micro-A plug features 10 pins to support SuperSpeed data rates, whereas the USB 2 version typically has 5 pins. Physically, the USB 3 version is distinct enough to be classified separately from the USB 2 Micro-A plug. ### Q: What devices use the USB 3 Micro-A plug? A: This plug was used as a legacy host connector in devices requiring high-speed data transfer in a compact form factor before the industry transitioned to USB-C. It is designed to plug into USB 3 Micro-AB receptacles, often found on older mobile devices and On-The-Go (OTG) adapters. ### Q: Can I plug a USB 3 Micro-A plug into a standard USB 3 Standard-A port? A: No, the physical form factor of the Micro-A plug is much smaller than the larger, rectangular USB 3 Standard-A plug (the typical rectangular port found on computers). They are distinct connector shapes. ## Why It Matters The USB 3 Micro-A plug represents a specific, compact iteration in the evolution of USB technology, bridging the gap between the original Standard-A connector and the modern USB-C standard. As a "host end" connector in a micro form factor, it enabled high-speed SuperSpeed+ (up to 10 Gbps) data capabilities in small portable devices, a significant technical achievement over the slower USB 2.0 Micro connectors. Although it is now considered a legacy interface replaced by the universal USB-C plug, the USB 3 Micro-A plug is notable for its complex 10-pin design. This design integrated ground drain pins and dedicated super-speed transmitter/receiver lanes (SSTX/SSRX), setting a precedent for the high-density pinouts seen in modern connectors. It serves as a historical marker of the transition period where the industry sought to miniaturize high-bandwidth connectivity before consolidating around the reversible USB-C standard. ## Notable For * **High Pin Density:** Features a total of 10 leads, allowing for advanced data lanes like SSTX+ and SSRX+ in a compact size. * **Host Designation:** Notable for being a "Micro" variant that served the "A" (host) function, distinct from the more common "B" (device) micro connectors. * **Pre-USB-C Legacy:** It is the immediate predecessor connector class that was superseded by the USB-C plug. * **Specific Color Coding:** Uniquely requires a white insulator color for visual identification according to official specifications. ## Body ### Technical Specifications The USB 3 Micro-A plug, officially referenced as the USB 3.1 Micro-A plug, is a high-performance connector standardized by the USB Implementers Forum. Unlike the rectangular Standard-A connectors, this plug is designed for micro-sized applications. Structurally, it contains 10 leads, doubling the pin count of earlier USB 2.0 micro connectors to accommodate faster speeds. The pinout configuration is as follows: * **Pin 1:** VBUS (Red) - Power supply. * **Pin 2:** D− (White) - Data minus. * **Pin 3:** D+ (Green) - Data plus. * **Pin 4:** ID - Used for USB On-The-Go (OTG) identification. * **Pin 5:** GND (Black) - Ground. * **Pin 6:** SSTX− - SuperSpeed Transmit minus. * **Pin 7:** SSTX+ - SuperSpeed Transmit plus. * **Pin 8:** GND_DRAIN - Ground drain for signal integrity. * **Pin 9:** SSRX− - SuperSpeed Receive minus. * **Pin 10:** SSRX+ - SuperSpeed Receive plus. ### Classification and Relations This entity falls under several connector classes, including the **USB 3 Type-A connector** and **USB Micro-A plug**. It is crucial to distinguish this plug from similar counterparts: * **USB 3 Standard-A plug:** The full-sized, rectangular host connector. * **USB 3 Micro-B plug:** A different micro form factor typically used for peripheral devices rather than hosts. * **USB 2 Micro-A plug:** The slower, 5-pin predecessor. ### Status and Succession The USB 3 Micro-A plug is categorized as a legacy connector. It has been explicitly replaced by the **USB-C plug**, which offers a reversible design and a unified standard for both hosts and devices. Despite its legacy status, official documentation from the USB Implementers Forum (including the USB 3.1 Legacy Cable and Connector Revision 1.0) maintains the specifications for this plug, ensuring interoperability support for existing hardware. ## 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/universal-serial-bus-31-legacy-connectors-and-cable-assemblies-compliance-document) 3. [Source](https://www.usb.org/document-library/usb-32-revision-11-june-2022) 4. [Source](https://www.usb.org/document-library/usb-type-cr-connectors-and-cable-assemblies-compliance-document-rev-21b) 5. [Source](https://www.usb.org/document-library/usb-type-cr-cable-and-connector-specification-release-24)