USB-A Pinout Diagram and 4-Pin Signal Map
4-pin rectangular connector
Standards: USB 1.1, USB 2.0, USB 3.0, USB 3.1, USB 3.2, USB Battery Charging 1.2
What is the USB-A pinout?
The USB Type-A Connector has 4 pins. Pin 1 is VBUS (power). Pin 2 is D- (data). Pin 3 is D+ (data). Pin 4 is GND (ground).
Standards: USB 1.1, USB 2.0, USB 3.0, USB 3.1, USB 3.2, USB Battery Charging 1.2
Pin Assignment Table
| Pin | Signal | Type | Description |
|---|---|---|---|
| 1 | VBUS | power | +5V Power Supply (Red wire) - Provides 5V DC power up to 500mA (USB 2.0) or 900mA (USB 3.0) |
| 2 | D- | data | Data Minus (White wire) - Differential data signal negative, paired with D+ |
| 3 | D+ | data | Data Plus (Green wire) - Differential data signal positive, paired with D- |
| 4 | GND | ground | Ground (Black wire) - Power and signal ground reference |
Signal Types
Common Applications
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Browse more connector references →The USB-A connector has 4 pins: Pin 1 (VBUS, 5V), Pin 2 (D-), Pin 3 (D+), and Pin 4 (GND). Common in PC Peripherals and Phone and tablet chargers.
USB Type-A Pinout Guide
USB Type-A is the original host-side USB connector, introduced with USB 1.0 in 1996 and still ubiquitous today. The standard USB-A connector has 4 pins for USB 2.0 operation (VBUS, D-, D+, GND), while USB 3.0 Type-A connectors add 5 additional pins internally for SuperSpeed data transfer while maintaining backward compatibility with USB 2.0 devices. The rectangular shape and keying ensure the connector can only be inserted one way, though this requires users to orient the plug correctly.
Wiring Tips & Best Practices
Standard USB wire colors follow a universal convention: Red = VBUS (+5V power), White = D- (Data Minus), Green = D+ (Data Plus), and Black = GND (Ground). However, always verify with a multimeter as some low-quality cables do not follow this standard. For power-only charging cables, D+ and D- may be shorted together or connected through specific resistor values to signal charging capability to the device. The USB Battery Charging 1.2 specification defines how D+ and D- should be configured for dedicated charging ports (DCP), standard downstream ports (SDP), and charging downstream ports (CDP).
Common Issues
Charge-only cables lack D+/D- data wires entirely or have them disconnected, preventing data transfer while still allowing charging. To identify a charge-only cable, check continuity on the white and green wires. USB OTG (On-The-Go) requires a special cable with the ID pin (Pin 4 on Micro-USB) grounded to enable host mode on mobile devices. Cheap cables with thin wire gauges (28 AWG or higher) cause voltage drop during high-current charging, resulting in slow charge rates or device not charging warnings. For reliable 2.4A charging, use cables with 24 AWG power wires or thicker.
Why Use Interactive Diagrams?
- Accuracy: Hover over pins to see exact signal names and descriptions
- Clarity: Color-coded by signal type (power, ground, data)
- Printable: Export clean diagrams for shop floor reference