What Is the Function of DVI Pin 15?

This article explains the specific role and technical function of pin 15 on a standard Digital Visual Interface (DVI) connector. It details the electrical purpose of this pin, its relationship to the DVI power and communication systems, and why it is essential for maintaining proper signaling between a video source and a display device.

On any standard DVI connector—including DVI-D (digital only), DVI-A (analog only), and DVI-I (integrated digital and analog)—pin 15 functions as a Ground (GND) connection. Specifically, it serves as the ground return for the +5V power rail, as well as the reference ground for sync signals.

Power Circuit Completion

Pin 14 on a DVI connector provides a +5V power feed from the graphics card to the display. Pin 15 provides the dedicated electrical ground return path required to complete this low-voltage DC circuit.

This +5V line is primarily used to power the monitor's Extended Display Identification Data (EDID) EEPROM chip via the Display Data Channel (DDC). Because of the closed circuit formed by pin 14 (+5V) and pin 15 (ground return), a computer can read the monitor’s supported resolutions, color capabilities, and refresh rates even if the monitor is powered off or in standby mode.

Sync Signal Ground Reference

In analog and integrated implementations (DVI-A and DVI-I), pin 15 also functions as the ground return for horizontal synchronization (H-Sync) and vertical synchronization (V-Sync) lines. A stable, low-noise ground reference is critical for these timing signals to prevent display jitter, image tearing, or signal synchronization failures.

Impact on Display Operation

If pin 15 is damaged, disconnected, or missing:

  • Detection Failures: The host computer may fail to detect the connected display, leading to "No Signal" errors.
  • Resolution Issues: The operating system may be unable to read EDID data, forcing the display into a low-resolution generic fallback mode (such as 640x480 or 800x600).
  • Hot-Plug Malfunctions: The hot-plug detection mechanism (pin 16), which relies on voltage changes relative to ground, may become erratic or fail to report connection events.