Connector Pinouts
Common connector pinouts — USB, Ethernet, audio, serial, power.
Reference
USB Type-A 2.0
| Pin | Signal | Color |
|---|---|---|
| 1 | VBUS (+5 V) | Red |
| 2 | D− | White |
| 3 | D+ | Green |
| 4 | GND | Black |
RJ-45 / Ethernet (T568B)
| Pin | Pair | Color | 1G function |
|---|---|---|---|
| 1 | 2 tip | White-Orange | BI_DA+ |
| 2 | 2 ring | Orange | BI_DA− |
| 3 | 3 tip | White-Green | BI_DB+ |
| 4 | 1 ring | Blue | BI_DC+ |
| 5 | 1 tip | White-Blue | BI_DC− |
| 6 | 3 ring | Green | BI_DB− |
| 7 | 4 tip | White-Brown | BI_DD+ |
| 8 | 4 ring | Brown | BI_DD− |
3.5 mm TRS / TRRS audio
| Segment | TRS | TRRS (CTIA) | TRRS (OMTP) |
|---|---|---|---|
| Tip | Left | Left | Left |
| Ring 1 | Right | Right | Right |
| Ring 2 / Sleeve | GND | GND | Mic |
| Sleeve | — | Mic | GND |
DB-9 (RS-232 DTE)
| Pin | Signal |
|---|---|
| 1 | DCD — Data Carrier Detect |
| 2 | RXD — Receive |
| 3 | TXD — Transmit |
| 4 | DTR — Data Terminal Ready |
| 5 | GND |
| 6 | DSR — Data Set Ready |
| 7 | RTS — Request To Send |
| 8 | CTS — Clear To Send |
| 9 | RI — Ring Indicator |
ATX 24-pin (power supply)
- +3.3 V (×4), +5 V (×5), +12 V (×2), −12 V (×1), +5 V SB (standby), PS_ON#, PWR_OK, and many GND pins.
- PS_ON# is pulled low by the motherboard to turn the supply on.
- Never short +12 V to GND — fuse / overcurrent protection may not save the PSU or peripherals.
Molex 4-pin (peripheral power)
| Pin | Color | Signal |
|---|---|---|
| 1 | Yellow | +12 V |
| 2 | Black | GND |
| 3 | Black | GND |
| 4 | Red | +5 V |
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