A standard USB cable is typically wired with four conductors, specifically designed to handle both power and data transmission.
Understanding the Conductors
Inside a standard USB cable, you will find four individual wires serving distinct purposes: two for delivering electrical power and two for carrying data signals. This separation ensures that power delivery and data communication can happen simultaneously and reliably.
Power Wires
There are two conductors dedicated to providing power. These wires are responsible for supplying voltage (VBUS) to the connected device and providing a ground return path (GND).
- Gauge: The power wires have a gauge ranging from 20 to 28 AWG (American Wire Gauge). A lower AWG number indicates a thicker wire.
- Length & Gauge: Longer cables will use 20 AWG for power, as thicker wires reduce voltage drop over distance, ensuring sufficient power reaches the device.
- Twist: The power cores are un-twisted.
Data Wires
Alongside the power wires, there are two conductors used for data transfer. These wires carry the differential data signals, often referred to as D+ and D-.
- Gauge: The data wires are specified as 28 AWG.
- Twist: The data lines are twisted. This twisted pair configuration helps reduce electromagnetic interference (EMI) and crosstalk, ensuring signal integrity for reliable data transmission.
Summary of USB Cable Wiring
Based on the standard wiring, the internal structure can be summarized as follows:
| Wire Type | Function | Count | Gauge (AWG) | Twist Status |
|---|---|---|---|---|
| Power | VBUS, GND | 2 | 20 to 28 | Un-twisted |
| Data | D+, D- | 2 | 28 | Twisted |
This specific arrangement of four conductors, with dedicated and differentiated power and data lines (including variations in gauge and twisting), is fundamental to how a standard USB cable functions.
