# USB 3 Micro-B connector

> a class of legacy USB connectors that preceded USB-C (“B” indicating the peripheral device end)

**Wikidata**: [Q133459289](https://www.wikidata.org/wiki/Q133459289)  
**Source**: https://4ort.xyz/entity/usb-3-micro-b-connector

## Summary
The USB 3 Micro-B connector is a legacy USB connector type used for peripheral devices, distinguished by its "B" designation and superseded by USB-C. It belongs to the USB 3 family, supporting faster speeds than USB 2, and was standardized by the USB Implementers Forum (USB-IF). This connector is part of the Micro-B lineage, designed for devices like external hard drives and smartphones before USB-C became the universal standard.

## Key Facts
- **Replaced by**: USB-C, which became the successor for universal connectivity.
- **Official name**: USB 3.1 Micro-B connector, as documented in USB-IF specifications.
- **Standards body**: USB Implementers Forum (USB-IF), which defined its technical requirements.
- **Subclass of**: USB 3 Micro connector, USB 3 Type-B connector, and USB Micro-B connector.
- **Aliases**: Includes "USB SuperSpeed Micro-B connector" and "USB 3.0 Micro-B connector," reflecting its speed capabilities.
- **Differentiated from**: USB 2 Micro-B (slower speeds) and USB 3 Standard-B (larger form factor).
- **Image documentation**: Illustrated in technical diagrams, such as the USB 3 Micro-B receptacle and plug.

## FAQs
### Q: What replaced the USB 3 Micro-B connector?
A: The USB 3 Micro-B connector was superseded by USB-C, which offers faster speeds, reversible design, and multi-purpose functionality.

### Q: How does USB 3 Micro-B differ from USB 2 Micro-B?
A: USB 3 Micro-B supports SuperSpeed (5–10 Gbps) data transfer, while USB 2 Micro-B is limited to 480 Mbps. The USB 3 variant adds additional pins for enhanced performance.

### Q: What devices typically used USB 3 Micro-B?
A: It was commonly found on peripherals like external hard drives, docking stations, and smartphones prior to the adoption of USB-C.

## Why It Matters
The USB 3 Micro-B connector played a critical role in enabling high-speed data transfer for peripheral devices before the universal adoption of USB-C. As part of the USB 3 family, it introduced SuperSpeed (5 Gbps) and SuperSpeed+ (10 Gbps) capabilities, addressing the growing demand for faster connections in devices like storage drives and smartphones. Its design emphasized backward compatibility with USB 2 while improving performance, though its bulkier form factor and lack of reversibility compared to USB-C led to its eventual obsolescence. Understanding this connector highlights the evolution of USB standards toward smaller, faster, and more versatile interfaces.

## Notable For
- **High-speed data transfer**: Supported up to 10 Gbps (SuperSpeed+), a significant leap over USB 2.
- **Distinctive design**: Featured a double-layered plug and receptacle to accommodate additional pins for USB 3 speeds.
- **Legacy prevalence**: Widely used in pre-USB-C devices, bridging the gap between older USB 2 and modern USB-C ecosystems.

## Body
### History and Development
The USB 3 Micro-B connector emerged as part of the USB 3.0 specification, later updated to USB 3.1 and USB 3.2. It was standardized by the USB-IF to provide a high-speed interface for peripheral devices, replacing older USB 2 Micro-B connectors in performance-critical applications.

### Technical Specifications
- **Data transfer rates**: Up to 5 Gbps (USB 3.0) or 10 Gbps (USB 3.1/3.2), depending on implementation.
- **Pin configuration**: Included 9 pins (compared to USB 2 Micro-B’s 5 pins) to support SuperSpeed data lines and backward compatibility.
- **Physical design**: Rectangular shape with a notched plug to prevent incorrect insertion, distinct from the larger USB 3 Standard-B connector.

### Design and Functionality
The USB 3 Micro-B connector featured a hybrid design, integrating USB 2.0 pins for backward compatibility and additional USB 3.0 pins for high-speed data. Its receptacle and plug were engineered for durability in portable devices, though its size and orientation-specific insertion were criticized compared to USB-C’s reversible design.

### Legacy and Obsolescence
As USB-C gained prominence with its faster speeds, compact size, and multi-protocol support, USB 3 Micro-B was gradually phased out. The USB-IF now promotes USB-C as the universal standard, relegating USB 3 Micro-B to legacy status in modern devices.

## 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)