USB Pin Assignment: All Connector Types & Wire Colors Explained
USB 2.0, USB 3.x, USB-C — the pin layout varies significantly across generations and connector form factors. This page provides the complete pin assignment for all common USB types with color-coded wire diagrams — ready for use in cable assembly, fault diagnosis and component planning.
| Standards Note: The USB specification is maintained by the USB Implementers Forum (USB-IF). Wire colors are defined in the standard but may differ with third-party manufacturers — when in doubt, always verify with a multimeter. |
1. USB 2.0 Pin Assignment
USB 2.0 (Hi-Speed, up to 480 Mbit/s) is the oldest USB standard still widely deployed. Type A and Type B connectors have four pins: two data lines (D− and D+), power supply (VBUS, +5 V) and ground (GND). Micro and Mini variants add a fifth pin (ID) for USB OTG host/peripheral detection.
USB 2.0 Type A & Type B — Pin Assignment
| Pin | Name | Description | Wire Color | Voltage / Signal |
|---|---|---|---|---|
| 1 | VBUS | Bus power supply | Red | +5 V DC (max. 500 mA USB 2.0) |
| 2 | D− | Data line negative (differential signal) | White | Differential 0–3.3 V |
| 3 | D+ | Data line positive (differential signal) | Green | Differential 0–3.3 V |
| 4 | GND | Ground | Black | 0 V reference |
USB 2.0 Micro-B & Mini-B — Pin Assignment
Micro-B and Mini-B (and their A-variants) add an ID pin (pin 4) through which the USB OTG protocol determines whether a device acts as host or peripheral. In standard cables (non-OTG) pin 4 remains unconnected.
| Pin | Name | Description | Wire Color | OTG |
|---|---|---|---|---|
| 1 | VBUS | Bus power +5 V | Red | — |
| 2 | D− | Data line negative | White | — |
| 3 | D+ | Data line positive | Green | — |
| 4 | ID | Device identification (OTG host/peripheral selection) | No wire (GND = host; open = peripheral) | OTG |
| 5 | GND | Ground | Black | — |
2. USB 3.0 / 3.1 / 3.2 Gen 1 Pin Assignment
With USB 3.0 (today USB 3.2 Gen 1, 5 Gbit/s SuperSpeed), four additional data lines were added. The original four USB 2.0 pins are retained (backward compatibility), supplemented by two SuperSpeed differential pairs for transmit (SSTX) and receive (SSRX), plus a shared drain ground (GND_DRAIN).
Important: SSRX/SSTX designations are device-relative — what the Type-A port receives as SSRX is transmitted by the Type-B port as SSTX. Direction is swapped between connector types.
| Pin | Name | Description | Wire Color | Standard |
|---|---|---|---|---|
| 1 | VBUS | Bus power +5 V (900 mA with USB 3.x) | Red | USB 2.0 / 3.x |
| 2 | D− | Hi-Speed data negative (USB 2.0) | White | USB 2.0 / 3.x |
| 3 | D+ | Hi-Speed data positive (USB 2.0) | Green | USB 2.0 / 3.x |
| 4 | GND | Ground | Black | USB 2.0 / 3.x |
| 5 | SSRX− | SuperSpeed receive negative (Type A) / transmit negative (Type B) | Blue | USB 3.x |
| 6 | SSRX+ | SuperSpeed receive positive (Type A) / transmit positive (Type B) | Yellow | USB 3.x |
| 7 | GND_DRAIN | Shared ground for SuperSpeed differential pairs | Bare wire (uninsulated) | USB 3.x |
| 8 | SSTX− | SuperSpeed transmit negative (Type A) / receive negative (Type B) | Violet | USB 3.x |
| 9 | SSTX+ | SuperSpeed transmit positive (Type A) / receive positive (Type B) | Orange | USB 3.x |
Legend: yellow background = USB 2.0 compatible pins, blue background = SuperSpeed-only pins. USB 3.0 Type B (Powered-B) optionally adds pin 10 (DPWR, peripheral power) and pin 11 (DGND).
3. USB-C Pin Assignment (24 Pins)
USB-C is the universal connector for USB 3.2, USB4 and Thunderbolt. It features 24 pins in two rows of 12 (side A top, side B bottom). The mirror-image layout enables reversible insertion — the trademark of the USB-C standard. Additional functions such as Power Delivery (up to 240 W), DisplayPort Alt Mode and Thunderbolt are negotiated via the CC pin (Configuration Channel).
USB-C Complete Pin Assignment (Side A)
| Pin A | Mirror (Side B) | Name | Function | Wire Color (A / B) |
|---|---|---|---|---|
| A1 | B12 | GND | Ground | Bare wire |
| A2 | B11 | SSTX+ | SuperSpeed transmit positive | Yellow (A) / White (B) |
| A3 | B10 | SSTX− | SuperSpeed transmit negative | Brown (A) / Black (B) |
| A4 | B9 | VBUS | Bus power (USB PD up to 240 W) | Red |
| A5 | B5 | CC1 / CC2 | Configuration Channel: orientation detection, Power Delivery negotiation, Alt Mode activation | Blue (A) / Yellow (B) |
| A6 | B7 | D+ | Hi-Speed data positive (USB 2.0) | White |
| A7 | B6 | D− | Hi-Speed data negative (USB 2.0) | Green |
| A8 | B8 | SBU1 / SBU2 | Sideband Use: auxiliary path for audio and DisplayPort Alt Mode | Red (A) / Black (B) |
| A9 | B4 | VBUS | Bus power (second VBUS pin) | Red |
| A10 | B3 | SSRX− | SuperSpeed receive negative | Blue (A) / Orange (B) |
| A11 | B2 | SSRX+ | SuperSpeed receive positive | Red (A) / Green (B) |
| A12 | B1 | GND | Ground | Bare wire |
| CC Pin (A5/B5) — The Key to USB-C Intelligence: The Configuration Channel negotiates at connection: which side is host, how much power to deliver (USB PD Profiles 5–48 V, up to 5 A = 240 W) and whether an Alternate Mode (DisplayPort, Thunderbolt, HDMI) should be activated. In simple charging cables without an E-Marker chip, CC pull-up/pull-down resistors (56 kΩ / 5.1 kΩ) are hardwired. |
4. Wire Colors — Overview and Tolerances
Wire colors are normatively defined in the USB standard but not always followed by third-party manufacturers. Budget cables in particular may deviate — the pin position is always authoritative, not the color.
| Wire Color | Pin Function | USB Version | Note |
|---|---|---|---|
| Red | VBUS (+5 V) | 2.0 / 3.x / C | Always the positive power supply. Higher voltages possible with USB PD. |
| White | D− (USB 2.0) | 2.0 / 3.x / C | Data line — not a power wire, do not confuse with VBUS. |
| Green | D+ (USB 2.0) | 2.0 / 3.x / C | Data line — differential pair with D−. |
| Black | GND | 2.0 / 3.x / C | Ground / reference potential. |
| Blue | SSRX− | 3.x | SuperSpeed receive negative (Type A). |
| Yellow | SSRX+ | 3.x | SuperSpeed receive positive (Type A). |
| Violet | SSTX− | 3.x | SuperSpeed transmit negative (Type A). |
| Orange | SSTX+ | 3.x | SuperSpeed transmit positive (Type A). |
| Bare wire | GND_DRAIN | 3.x / C | Uninsulated drain wire for SuperSpeed differential pair shielding. |
5. Practical Notes for B2B Procurement & Engineering
⚙ Cable AssemblyUSB 2.0 (4-wire) can still be hand-soldered with standard equipment. USB 3.x (9-wire) and USB-C (24-wire) require precision tooling and impedance control (90 Ω differential). For industrial applications, factory-assembled certified cables are preferred over custom assemblies. Maximum passive cable lengths per USB-IF: USB 2.0: 5 m • USB 3.x: 3 m • USB-C: 2 m (without active cable). |
⚔ Fault DiagnosisA simple continuity tester is sufficient for USB 2.0 cables. For USB 3.x and USB-C: test continuity of all 9 or 24 pins, verify no short between D+ and D−, and confirm shield continuity (GND_DRAIN to connector shell). For USB-C charging issues: test CC pin pull-up/pull-down resistance (missing E-Marker limits the cable to 5 V / 3 A). |
📜 StandardsGoverning standards: USB 2.0 Spec. (USB-IF, 2000), USB 3.2 Gen 1/2 (USB-IF, 2019), USB4 Version 2.0 (USB-IF, 2022), IEC 62680 (international USB interface standard). For USB PD: IEC 62680-1-2. Product labeling per USB-IF: Performance Logos 5G, 10G, 20G, 40G.
|
⚡ Power DeliveryUSB-C cables rated above 60 W must contain an E-Marker chip (electronically marked) that signals cable capacity and current rating to the host. Without E-Marker, the device automatically limits to 5 V / 3 A (15 W). For EPR (Extended Power Range, 100+ W), certified EPR cables are mandatory. |
Frequently Asked Questions about USB Pin Assignment
How many wires does a USB cable have?
USB 2.0 cables have 4 wires (VBUS, D−, D+, GND). USB 3.x cables have 9 wires (plus drain wire = 10 in the cable). Full-spec USB-C cables can have up to 24 pins plus shield — but simple charging cables often only populate a subset of them.
Can USB-A plugs be hand-soldered?
USB 2.0 Type A and B connectors can be assembled with standard soldering equipment: 4 pins, 90 Ω pair impedance, shield connection. USB 3.x and USB-C connectors are barely suitable for hand-soldering due to the 9 or 24 closely spaced pins and impedance requirements. Factory-assembled cables are more reliable for these.
What is the CC pin in USB-C?
The CC pin (Configuration Channel, A5/B5) handles several functions during USB-C connection: it detects which side acts as host, negotiates Power Delivery capacity, and activates Alternate Modes such as DisplayPort or Thunderbolt. Without the CC pin, USB-C cables are incompatible with PD and Alt Mode — in some cases not recognized at all.
Why does USB 3.x speed drop on some cables?
Common causes: the cable has a USB 3.x connector body but is internally only 4-wire (USB 2.0 pins only) — SuperSpeed pins 5–9 are absent. Other causes: inadequate shielding on SuperSpeed pairs, cable length exceeding the passive limit (3 m), or missing GND_DRAIN continuity. Fix: use USB-IF certified cables with the correct wire count (minimum 9 wires for USB 3.x).
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Questions about cable wiring or connector specifications? Our technical sales team: +49 (0)7666 / 88499-0 • sales@industry-electronics.com |
Further reading: USB Port Colors Explained • Connector Glossary • Video Connector Overview •