RJ45 Connector Pinout

Pin Arrangement Rules

1. Viewing Angle:
   When viewed from the front of the female connector (the direction the plug is inserted), with the tab facing down and the metal contacts facing you, the leftmost pin is Pin 1, and the rightmost is Pin 8.
2. T568A Standard:
   • Pin 1: White-green (Receive Data Positive RX+)
   • Pin 2: Green (Receive Data Negative RX-)
   • Pin 3: White-orange (Transmit Data Positive TX+)
   • Pin 4: Blue (Unused / Gigabit bidirectional data +)
   • Pin 5: White-blue (Unused / Gigabit bidirectional data -)
   • Pin 6: Orange (Transmit Data Negative TX-)
   • Pin 7: White-brown (Unused / Gigabit bidirectional data +)
   • Pin 8: Brown (Unused / Gigabit bidirectional data -)
     Mnemonic: Green, blue, orange, brown; light colors first, swap pins 3 and 5.
3. T568B Standard:
   • Pin 1: White-orange (Transmit Data Positive TX+)
   • Pin 2: Orange (Transmit Data Negative TX-)
   • Pin 3: White-green (Receive Data Positive RX+)
   • Pin 4: Blue (Unused / Gigabit bidirectional data +)
   • Pin 5: White-blue (Unused / Gigabit bidirectional data -)
   • Pin 6: Green (Receive Data Negative RX-)
   • Pin 7: White-brown (Unused / Gigabit bidirectional data +)
   • Pin 8: Brown (Unused / Gigabit bidirectional data -)
     Mnemonic: Orange, blue, green, brown; light colors first, swap pins 3 and 5.

Key Features and Applications

1. Data Transmission:
   • 10/100Base-T: Uses only pins 1, 2, 3, and 6 (two pairs of differential signals), with T568B being more common.
   • Gigabit Ethernet (1000Base-T): Uses all 8 pins to enable bidirectional data transmission.
2. Crossover vs. Straight-Through Cables:
   • Straight-through cable: Both ends use T568B or T568A, used to connect different devices (e.g., a computer and a switch).
   • Crossover cable: One end uses T568B, the other T568A, used to connect similar devices (e.g., a computer to another computer).
3. PoE (Power over Ethernet):
   • Mode A: Delivers power through pins 1, 2, 3, and 6 (data and power share the same pairs).
   • Mode B: Delivers power through pins 4, 5, 7, and 8 (using idle pairs).
4. Pin Identification:
   Female connectors typically have no additional markings; the direction is determined by the tab position (when the tab is facing down, the leftmost is Pin 1).

Notes

• Compatibility: T568A and T568B can be mixed, but ensure consistency between both ends or use a crossover cable.
• Special Designs: Some female connectors with network transformers may adjust pin functions, but the arrangement still follows the standards.
• Shielded vs. Unshielded: Shielded female connectors must be used with shielded cables; the pin arrangement remains unchanged.