HDMI one of the most common connectors for video and audio interfaces. This versatile interface helps you run high-resolution and high refresh rate displays that the older VGA and DVI interfaces just can’t.
But does HDMI carry power along with video and audio signals? The answer is yes, they do carry power. But not enough to power devices like external displays.
In other words, they do not carry power like the way a USB port does. HDMI interface is, in fact, not designed to deliver power.
The powered delivered by HDMI is NOT sufficient to run monitors, TVs, PC etc.
How Does HDMI Work?
HDMI cables are one of the most popular ways to connect audio and video devices. But to understand why HDMI does not carry power, you have to understand how a typical HDMI cable works.
HDMI stands for High-Definition Multimedia Interface. These cables are able to carry both digital video and audio signals.
The latest and greatest in HDMI technology is HDMI 2.1, which is able to support resolutions up to 8K and data transfer speeds up to 48 Gbps. HDMI cables are also able to transmit Dolby TrueHD and DTS-HD Master Audio signals.
Most consumer devices use a 19-pin type A HDMI connector. There’s a mini-HDMI connector also available, but the regular one is far more popular.
The signals travel from the HDMI connector’s pins via twisted pairs of copper wire. Six pins are used to transmit three audio and video channels, for a total of three cables per channel.
The TMDS (Transition-minimized differential signaling) clock, which allows devices to synchronize the incoming data, travels through one pair of wires.
Each of these four main cable pairs contains a shield which is another wire that protects the neighbor wires from interference.
These are the components that make up the bulk of wires in an HDMI cable. The HDMI connection transmits other signals in addition to video. Because only one pin is necessary per channel, this means that the rest of the signals that travel via the HDMI cable can be sent over a single wire.
The consumer electronics channel (CEC) is one such channel. If your devices support it, this channel allows them to “talk” to each other.
The hot plug detect channel, which has only one connection, monitors when you connect or disconnect a device and re-initializes the HDMI link if required.
The one-pin display data channel (DDC) carries device information as well as HDCP (high-bandwidth digital copy protection) encryption information. This protects the data traveling through the HDMI cables.
Also Read: Does HDMI Drain Battery?
HDMI Pin Out Diagram
Here is the pin-out diagram of a Standard HDMI connector with 19 pins.
|Pin 1||TMDS Data2+||Pin 11||TMDS Clock Shield|
|Pin 2||TMDS Data2 Shield||Pin 12||TMDS Clock−|
|Pin 3||TMDS Data2−||Pin 13||CEC|
|Pin 4||TMDS Data1+||Pin 14||Not Connected|
|Pin 5||TMDS Data1 Shield||Pin 15||SCL (DDC)|
|Pin 6||TMDS Data1−||Pin 16||SDA (DDC)|
|Pin 7||TMDS Data0+||Pin 17||Ground|
|Pin 8||TMDS Data0 Shield||Pin 18||+5 V (50 mA max)|
|Pin 9||TMDS Data0−||Pin 19||Hot Plug Detect|
|Pin 10||TMDS Clock+|
The only pin that carried voltage is the Pin # 18 but it has a max current rating of 50 mA. Meaning the maximum amount of power it can carry is 0.25W.
So Does HDMI Carry Power?
Yes, HDMI does carry power.
The power in the Pin # 18, on the other hand, can be used to power devices.
However, 0.25W of power is not nearly enough to power up majority of the multimedia devices out there.
It should be noted that the TMDS channels also carry power. However, the power on these channels is intended for carrying the video and audio signals not for powering up devices.
Can HDMI Power Devices?
As mentioned, the maximum operational voltage for HDMI is 5 volts and the maximum current it can carry is 50mA over just one pin that is intended for delivering power to connected devices.
The primary goal of the HDMI interface is NOT to power up or charge devices. This is why external displays have their own separate power source.
A typical PC monitor easily requires anywhere 25-60Watts of power.
But let’s say you really want to power something with HDMI. If you somehow cobbled this thing together, it would probably only last a minute before the wires melted and the whole thing spectacularly collapsed. It might fry your monitor or computer, or possibly both.
So can HDMI power anything? Well, no.
Unfortunately there is no device out there that uses only 0.25W to power up.
Even the lightest multimedia devices such as the Chromecast requires 1-2 watts or 4-8 times the amount of powered delivered by the HDMI port.
Hence, as it stands, currently almost all devices that use the HDMI interface require an external power source.
Also Read: Does HDMI Cable Cause Lags?
HDMI 2.1a and Cable Power Feature
In the latest revision of the HDMI version i.e 2.1a, a new feature called HDMI Cable Power has been added which allows supported devices to be connected without needing a separate power cable.
This feature is mostly intended for allowing support for active HDMI cables to be powered directly through the port.
However, since this feature can supply 5v @ 300mA which equals 1.5W, we may certain and more efficient multimedia devices make use of this feature. Or perhaps we may not see any device at all.
Also Read: What is the Best HDMI Port for Gaming?
Do HDMI Cables Carry Electricity?
For those who are unaware, in colloquial language, the term power and electricity are used interchangeably.
However, in technical terms, electricity is the flow of electrical charges measured in ohms.
So yes, HDMI cables do carry electricity of about 50 milli-Amps (mA).
If you are worried about electrocuting yourself by touching the HDMI connector than rest assured, 50mA is not nearly sufficient to even register a faint feeling of electricity running through your body.
How Many Volts Does an HDMI Cable Carry?
An HDMI cable carries 5Volts.
So does HDMI carry power? Yes, the HDMI interface does carry power, but the power it carries is not nearly enough to power our everyday devices.
In fact, there is no device out there, except for the cable itself, that can get powered directly through the HDMI port despite the fact that one of the pins carries 5V at 30mA max.
This amount of electricity is only enough to allow communication between the devices they are connected to. So, while you won’t be powering any displays with HDMI anytime soon, HDMI is still a versatile connector that can transmit audio and video signals to upto 8K displays and beyond.