# USB 3 Micro-B plug

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

**Wikidata**: [Q133458747](https://www.wikidata.org/wiki/Q133458747)  
**Source**: https://4ort.xyz/entity/usb-3-micro-b-plug

## Summary
The USB 3 Micro-B plug is a legacy USB connector located at the peripheral device end of a cable, distinguished by its 10-pin configuration. It preceded the modern USB-C standard and is officially designated as the USB 3.1 Micro-B plug.

## Key Facts
- **Official Name:** USB 3.1 Micro-B plug
- **Succession:** Preceded USB-C; eventually replaced by the USB-C plug.
- **Pin Configuration:** Features 10 leads (pins), in contrast to the 5 pins found on earlier USB 2 Micro-B plugs.
- **Compatibility:** Connects with USB 3 Micro-AB receptacles and USB 3 Micro-B receptacles.
- **Function:** Serves as the "B" end of the connection, indicating the peripheral device side.
- **SuperSpeed Lanes:** Includes dedicated pins for SuperSpeed transmit (SSTX+, SSTX−) and receive (SSRX+, SSRX−) data transfer.
- **Power:** Pin 1 (VBUS) carries a 5V power supply.
- **Aliases:** Also known as the SuperSpeed+ Micro-B plug, USB 10Gbps Micro-B plug, and Micro-USB 3.0 Type-B plug.

## FAQs
### Q: Is the USB 3 Micro-B plug the same as the older Micro-USB charger plug?
A: No, it is different from the USB 2 Micro-B plug. While physically related, the USB 3 version has 10 pins and a wider shape to accommodate SuperSpeed data transfer, whereas the USB 2 version has only 5 pins.

### Q: What replaced the USB 3 Micro-B plug?
A: The USB-C plug replaced the USB 3 Micro-B plug. The USB-C standard has largely superseded this and other legacy USB connectors.

### Q: What does the "B" in USB 3 Micro-B plug stand for?
A: The "B" indicates that the plug is designed for the "peripheral device end" of a connection (such as a hard drive), rather than the host (computer) end.

### Q: What are the color codes for the standard wires in this plug?
A: The standard wire color codes are Red for VBUS (Pin 1), White for D− (Pin 2), Green for D+ (Pin 3), and Black for GND (Pin 5).

## Why It Matters
The USB 3 Micro-B plug represents a specific evolutionary step in mobile and peripheral connectivity, bridging the gap between the slower USB 2.0 era and the modern USB-C standard. Historically, it addressed the need for faster data transfer rates—specifically SuperSpeed and 10Gbps speeds—in devices that still utilized the Micro-USB form factor.

Its design highlights the complexity of pre-USB-C connectivity, where different classes of plugs (Standard-B, Micro-B, Micro-A) were required for different speeds and device types. By incorporating an additional row of pins (totaling 10) for SuperSpeed data lanes (SSTX and SSRX) and a drain wire, it allowed legacy mobile devices and external peripherals to achieve significantly higher throughput than the 5-pin USB 2 Micro-B predecessor. Although now considered a legacy connector replaced by the reversible USB-C plug, the USB 3 Micro-B plug remains a key identifier for high-speed peripheral hardware from the USB 3.0 and 3.1 generations.

## Notable For
- **10-Pin Design:** Distinguished from its predecessors by having 10 leads (pins), allowing for dual-lane SuperSpeed data transfer.
- **USB 3.1 Standard:** Officially classified under the USB 3.1 specification (USB 3.1 Micro-B plug).
- **Legacy Status:** Serves as the immediate high-speed predecessor to the modern USB-C plug.
- **On-The-Go Support:** Retains the ID pin (Pin 4), allowing for USB On-The-Go (OTG) functionality.
- **Visual Identification:** Requires a specific black insulator color inside the plug housing.

## Body

### Definition and Classification
The USB 3 Micro-B plug is a class of legacy USB plugs designed for the peripheral device end of a cable. It is an instance of the USB 3 Micro-B connector, USB 3 Micro plug, and USB 3 Type-B plug classes. It is distinct from the USB 3 Micro-B receptacle (the port on the device) and the USB 3 Micro-A plug (used for host devices in the OTG context).

### Technical Pinout and Specifications
The plug features a 10-pin layout organized to support both legacy USB 2.0 data and newer SuperSpeed channels.
*   **Power and Ground:**
    *   **Pin 1 (VBUS):** Red wire, 5V IC power-supply.
    *   **Pin 5 (GND):** Black wire, Ground.
    *   **Pin 8 (GND_DRAIN):** Ground drain for signal integrity.
*   **Legacy Data (USB 2.0):**
    *   **Pin 2 (D−):** White wire.
    *   **Pin 3 (D+):** Green wire.
*   **SuperSpeed Data (USB 3.x):**
    *   **Pin 6 (SSTX−)** and **Pin 7 (SSTX+):** Transmitter differential pair.
    *   **Pin 9 (SSRX−)** and **Pin 10 (SSRX+):** Receiver differential pair.
*   **Configuration:**
    *   **Pin 4 (ID):** Used for USB On-The-Go identification.

### Relationships and Evolution
The USB 3 Micro-B plug connects mechanically with **USB 3 Micro-AB receptacles** and **USB 3 Micro-B receptacles**. It is structurally different from and cannot mate with a **USB 2 Micro-B plug** (which only has 5 pins) or the **USB 3 Standard-B plug** (which is larger).

This connector is considered "legacy" as it was eventually **replaced by the USB-C plug**, which offered a reversible design and a unified connector standard for both hosts and 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)