What Pin on an HDMI Cable Carries 5V Power?
On a standard 19-pin Type-A HDMI cable, Pin 18 carries the +5-volt power signal. This dedicated low-current power line supplies energy from the source device to the display to power internal circuitry, enable configuration communication when the monitor is turned off, and initiate handshake protocols.
The Role of Pin 18 in HDMI Connections
The HDMI specification defines Pin 18 as the +5V Power line. Unlike the data pins that transfer compressed or uncompressed audio and video via Transition-Minimized Differential Signaling (TMDS) or Fixed Rate Link (FRL), Pin 18 delivers direct current electricity.
Standard source devices—such as gaming consoles, PCs, and Blu-ray players—are required to provide a minimum of 55 mA at 4.7 to 5.3 volts on this pin. Many modern devices deliver significantly more current (often between 100 mA and 500 mA) to accommodate peripheral hardware like active optical cables, inline switches, and signal boosters.
Why HDMI Needs 5-Volt Power
The 5-volt supply on Pin 18 serves several vital functions in establishing an active connection:
- Powering the Display's EDID Chip: Displays store Extended Display Identification Data (EDID) on an internal EEPROM chip. Pin 18 powers this chip over the Display Data Channel (DDC), allowing the source device to read supported resolutions, refresh rates, and color depths even if the display is unplugged from mains power or set to standby mode.
- Driving Hot Plug Detect (HPD): Pin 19 functions as the Hot Plug Detect pin. When a display detects the 5V signal from Pin 18, it pulls Pin 19 high to notify the video source that a sink device is connected and ready for handshaking.
- HDCP Authentication: High-bandwidth Digital Content Protection relies on an active handshake over the DDC lines. Without the power supplied by Pin 18, the cryptographic exchange between the source and the display cannot occur.
- Active Accessory Power: Active HDMI splitters, signal extenders, and compact media streaming dongles often draw auxiliary operating current directly from Pin 18 instead of requiring a separate external power brick.
Pin 18 in the 19-Pin HDMI Layout
A standard HDMI Type-A connector organizes its pins into distinct functional groups. Pin 18 shares its physical area with the control and detection signals rather than the high-speed data pairs:
- Pin 15: SCL (DDC I2C Serial Clock)
- Pin 16: SDA (DDC I2C Serial Data)
- Pin 17: DDC/CEC/HEAC Ground
- Pin 18: +5V Power
- Pin 19: Hot Plug Detect
Because Pin 18 provides the essential operating voltage for handshaking, a damaged pin or broken wire inside the cable will result in a "No Signal" error, even if the high-speed TMDS audio and video lines remain completely intact.