Female USB Pinout: USB 2.0 Type-A Receptacle Wiring Reference

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The female USB Type-A receptacle has four pins: pin 1 VBUS (+5 V), pin 2 D– (data negative), pin 3 D+ (data positive), and pin 4 GND — the universal connector that powers and communicates with billions of USB devices.

The USB 2.0 Type-A receptacle (female connector) is the rectangular socket found on hosts — computers, chargers, hubs, and embedded systems — that accepts a USB Type-A plug. Understanding its pinout is essential for designing, repairing, or extending USB circuits correctly.

The USB Type-A receptacle has four signal contacts arranged in a single row:

Pin 1 — VBUS: the positive supply rail carrying nominally 5 V DC. The USB 2.0 specification allows the host to supply up to 500 mA per port (900 mA for USB 3.0 ports on USB 3.0-capable hosts). A downstream device draws current from this rail. The VBUS rail is protected internally in the host by a current-limiting resettable fuse (polyfuse) or electronic current limiter.

Pin 2 — D– (Data Minus): one conductor of the differential data pair. USB 2.0 uses a single differential pair for half-duplex serial communication, with High-speed (480 Mbit/s), Full-speed (12 Mbit/s), and Low-speed (1.5 Mbit/s) modes. D– is the negative signal of the differential pair.

Pin 3 — D+ (Data Plus): the positive signal of the differential data pair. Enumeration and device detection signals are also carried on D+ and D–. A resistor on D+ or D– pulled to 3.3 V in the connected device indicates device presence and speed capability to the host.

Pin 4 — GND: the signal return and power ground. The USB cable shield (on shielded cables) connects to the connector shell, which is bonded to GND on the PCB in most implementations.

The physical arrangement in the connector places pin 1 on the right side when viewing the receptacle's mating face with the opening facing you and the tab/retaining feature at the top. Pin 4 is on the left. Pins 2 and 3 are in the centre.

USB Charging specifications (USB Battery Charging, BC 1.2) use specific D– and D+ voltage conditions to negotiate higher charging currents. Apple's proprietary charging protocol places defined voltages on D+ and D– to signal current capacity. These protocols operate over the same four pins.

USB Type-C connectors have a different, rotationally symmetrical pinout with 24 pins and are not the subject of this reference page. This page covers USB 2.0 Type-A receptacles only.

How to wire female usb pinout

Identify the mating face orientation of the receptacle The USB Type-A receptacle has a rectangular opening. The plastic insulator tab inside the connector is at the top (or whichever orientation the connector is mounted on the PCB or panel). Orient the receptacle with its opening facing you and the tab at the top before assigning pin numbers.
Locate pin 1 (VBUS) on the right side With the opening facing you and the tab at the top, pin 1 (VBUS, +5 V) is the rightmost contact. On a PCB-mounted receptacle, pin 1 is the first pad from the right when the connector mating face is oriented as described. Use a multimeter and verify the pin carries approximately 5 V when the host is powered.
Identify pins 2 and 3 (D– and D+) in the centre The two centre contacts are the differential data pair. Pin 2 (D–) is adjacent to pin 1. Pin 3 (D+) is adjacent to pin 4. These are the smaller contacts (usually 0.64 mm width) flanked by the larger power contacts. Verify by checking that the wire colours in a standard USB cable are white (D–) and green (D+) at these positions.
Locate pin 4 (GND) on the left side With the opening facing you and the tab at the top, pin 4 (GND) is the leftmost contact. This connects to the circuit's common ground. Verify with a multimeter that it shows continuity to the circuit's ground plane.
Verify the connector shield connection The metal shell of the USB Type-A receptacle is electrically connected to the connector's shield tab(s) on the PCB. In most USB designs, the shell is connected to GND (signal ground) at the host. If the design uses chassis ground separately from signal ground, verify the shielding plan matches the applicable EMC requirement.
Check voltage and data integrity with a USB analyser or multimeter With a known-good USB device connected, verify VBUS is 5.0 V ±0.25 V (USB 2.0 spec: 4.75–5.25 V at the device). Use a USB protocol analyser to verify D+/D– signal integrity if data communication problems are suspected. Do not probe D+ and D– with a standard multimeter during USB data transfer — the probe capacitance disrupts high-frequency USB signals.

Specifications

Pin 1 — VBUS	+5 V DC (4.75–5.25 V per USB 2.0 specification at device)
Pin 2 — D–	Data minus (negative differential data signal)
Pin 3 — D+	Data plus (positive differential data signal)
Pin 4 — GND	Power and signal ground
Maximum current (USB 2.0 standard host port)	500 mA
Maximum current (USB 3.0 host port)	900 mA
USB 2.0 High-speed data rate	480 Mbit/s
D+/D– differential impedance	90 Ω ± 15% (USB 2.0 specification)

Safety warnings

Do not connect external power sources to the VBUS (pin 1) of a USB host port. VBUS is a power output on host ports, not an input. Backfeeding power through VBUS can damage the host device's USB port controller, power management IC, or motherboard.
Do not probe D+ (pin 3) or D– (pin 2) with a standard multimeter probe during active USB data transfer. The probe adds capacitance to the data line, corrupting high-speed signals and potentially causing enumeration errors. Use only a USB-specific protocol analyser or differential probe with appropriate bandwidth.
Short-circuiting VBUS (pin 1) to GND (pin 4) will trip the host's overcurrent protection. While polyfuses are resettable, repeated short circuits can degrade the fuse. In self-powered bus-powered applications, a short circuit can also draw damaging currents from the powered hub or host before the protection responds.
USB connectors are mechanically rated for a finite number of insertion cycles (typically 1 500–10 000 cycles depending on connector quality). Frequent connect-disconnect cycling on a fixed receptacle will eventually cause connector failure. Use a panel extension cable to protect frequently accessed receptacles.

Tools needed

Digital multimeter with DC voltage and continuity functions
USB protocol analyser or USB sniffer (for data line testing)
Anti-static wrist strap and mat (when handling PCB-mounted connectors)
Soldering iron and solder (for through-hole receptacle replacement)
Hot-air rework station (for SMD USB receptacle replacement)
USB cable for functional testing

Common mistakes

Reversing VBUS (pin 1) and GND (pin 4) when wiring a custom USB cable or breakout board, causing immediate damage to the connected device and possibly the host.
Swapping D+ (pin 3) and D– (pin 2), causing USB enumeration failure — the device will not be recognised by the host. Communication will appear to work at electrical level but protocol decoding will fail.
Omitting the VBUS overcurrent protection polyfuse in a custom USB port design, allowing a faulty or non-compliant device to draw excessive current without protection.
Connecting the connector shell (shield) to a separate chassis ground rather than to signal GND, creating a potential difference between the device and host ground that can cause data errors or damage ESD-sensitive inputs.
Using a USB cable with internal D+ and D– wires removed (a 'charge-only' cable) for a data transfer application — these cables support power only and will not carry USB data signals.

Troubleshooting

Connected USB device not recognised by host: Cause: D+ and D– swapped (pins 2 and 3 reversed in custom wiring), or a charge-only cable with no data conductors is in use. Fix: Check cable or wiring for correct D+/D– pin assignment. Test with a verified data-capable USB cable. Measure D+ for a 3.3 V pull-up when the device is connected — this confirms the device is attempting enumeration. If pull-up is present but device is not recognised, the fault is in the host USB controller or driver.
USB port supplies no VBUS voltage: Cause: Blown or tripped polyfuse on VBUS, or host has disabled the port due to an overcurrent fault. Fix: Measure voltage at pin 1 with a multimeter (no device connected). If VBUS is 0 V, check the polyfuse resistance — a tripped polyfuse shows high resistance. Remove the overcurrent device, let the polyfuse cool, and re-test. Replace the polyfuse if it does not recover.
USB device works intermittently or disconnects randomly: Cause: Poor mechanical connection — bent or recessed contacts in the receptacle due to wear or foreign object damage. Fix: Visually inspect the receptacle contacts under magnification. Gently clean the contacts with isopropyl alcohol on a cotton swab. If contacts are bent or broken, replace the receptacle. Test with a short, rigid USB plug rather than a heavy cable that may apply leverage to the connector.

Frequently asked questions

What are the four pins of a female USB Type-A connector?

Pin 1 is VBUS (+5 V power). Pin 2 is D– (data minus, negative of the differential pair). Pin 3 is D+ (data plus, positive of the differential pair). Pin 4 is GND (signal return and power ground). This pin assignment is defined by the USB 2.0 specification and is identical for all USB Type-A connectors regardless of manufacturer.

How much current can a USB Type-A port supply?

A standard USB 2.0 host port supplies up to 500 mA at 5 V (2.5 W). A USB 3.0 port supplies up to 900 mA (4.5 W). USB Battery Charging (BC 1.2) allows up to 1.5 A from a dedicated charging port. USB Power Delivery (USB-PD) supports much higher currents but only over USB Type-C connectors, not Type-A.

Which pin is pin 1 on a female USB Type-A receptacle?

When looking directly into the mating face (opening) of the receptacle with the plastic tab retention feature at the top, pin 1 (VBUS) is on the right side and pin 4 (GND) is on the left. Pins 2 (D–) and 3 (D+) are the two centre pins. The physical pin numbering reads 1-2-3-4 from right to left in this view.

What is the voltage on the D+ and D– pins when a device is connected?

At idle (no device), the host holds D+ and D– low via 15 kΩ pull-down resistors. When a Full-speed or High-speed USB device is connected, the device's D+ line is pulled up to 3.3 V through a 1.5 kΩ resistor inside the device. A Low-speed device pulls up D– instead. This pull-up is what the host detects as device connection.

Is the USB Type-A female pinout the same for USB 3.0?

USB 3.0 Type-A receptacles are physically and electrically backward-compatible with USB 2.0. The four-pin USB 2.0 contacts (pins 1–4) are identical in position and function. USB 3.0 adds five additional contacts behind the USB 2.0 contacts for SuperSpeed (SS) data transmission, but these are only present in USB 3.0 connectors and cables — USB 2.0 connectors do not have them.

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