Mini-DIN 6-Pin PS/2 Connector
6-pin circular connector
Standards: IBM PS/2 Technical Reference, Mini-DIN standard
What is the PS/2 pinout?
The Mini-DIN 6-Pin PS/2 Connector has 6 pins. Pin 1 is DATA (data). Pin 2 is NC (reserved). Pin 3 is GND (ground). Pin 4 is +5V (power). Plus 2 more pins.
Standards: IBM PS/2 Technical Reference, Mini-DIN standard
Pin Assignment Table
| Pin | Signal | Type | Description |
|---|---|---|---|
| 1 | DATA | data | Data (active low, open collector) |
| 2 | NC | reserved | Not Connected / Reserved |
| 3 | GND | ground | Ground |
| 4 | +5V | power | +5V Power (up to 275mA) |
| 5 | CLK | data | Clock (device-generated, 10-16 kHz) |
| 6 | NC | reserved | Not Connected / Reserved |
Signal Types
Common Applications
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Map this connector into your BOM workflow →The PS/2 connector has 6 pins: Pin 1 (DATA), Pin 2 (NC), Pin 3 (GND), and Pin 4 (+5V, 5V). Plus 2 more pins. Common in Desktop keyboards and Desktop mice.
PS/2 Keyboard & Mouse Pinout Guide
The PS/2 interface uses a synchronous serial protocol where the device provides the clock signal (10-16 kHz) and data is transmitted one bit at a time with odd parity. Communication is bidirectional - the host can send commands to the device (e.g., set keyboard LEDs, change mouse resolution). Unlike USB which requires driver initialization, PS/2 devices are available immediately at power-on, making them essential for BIOS configuration and systems without USB legacy support. The keyboard and mouse ports are electrically identical; the purple (keyboard) and green (mouse) color coding is purely conventional to prevent confusion.
Wiring Tips & Best Practices
PS/2 uses open-collector signaling with active-low logic. Both clock and data lines require pull-up resistors (1-10k ohms) to +5V - these are typically provided by the host controller. The clock line is always driven by the device during device-to-host communication, and by the host during host-to-device communication. Data is valid on the falling edge of the clock. When building adapters, ensure the +5V supply can provide at least 275mA for keyboards with LEDs or built-in hubs. The shield (metal shell) should be connected to ground for EMI protection.
Common Issues
Hot-plugging PS/2 devices can damage the port or device - always connect PS/2 devices with the system powered off. Some motherboards share a single PS/2 controller between both ports, causing issues when using both keyboard and mouse. USB-to-PS/2 adapters only work with devices that have built-in dual-mode support - passive adapters do not perform protocol conversion. Keyboards not working in BIOS but working in OS indicates USB legacy mode is disabled. Ghosting and key rollover issues on PS/2 are protocol limitations, not connector issues - some gaming keyboards use PS/2 specifically for better N-key rollover than USB. Erratic cursor movement or missed keystrokes often indicate timing issues from long cables or poor connections.
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