HDMI Forum’s HDMI 2.1a Cable Power Amendment Formally Revealed
The HDMI.org recently revealed the addition of an HDMI Cable Power “amendment 1” as part of the “HDMI 2.1a” digital connector standard.
The so-called amended HDMI 2.1a spec, which was first announced prior to CES 2021, will now add support for device power enabling the use of longer active HDMI Ultra High Speed cables that enable supporting devices to draw power without the need of a separate power source.
The organization refrains from using version numbers as an official label in public announcements instead asking members to list each product’s various supported HDMI features. This means anyone in need of this HDMI 2.1a Cable Power features must look for it to be specifically referenced in manufacturer’s feature support documentation and advertising.
Where referenced as such, the supported connected devices and special cable will be cable to carry device power to connected components without the need of a separate power connector. However, this feature will require special active HDMI Cable Power Ultra High Speed cables, supporting the expanded higher bandwidth benefits of that spec, at longer lengths than just a few meters, as supported under HDMI 2.1’s Fixed Rate Link (FRL) signaling system.
The HDMI.org said the new HDMI Cable Power specification allows HDMI Cables to be directly powered through the HDMI Connector, without the need of a separate power cable. Using HDMI Cable Power, the cable can draw up to 300 mA from the 5V supply of the source, according to the organization’s FAQ section of its web site.
The new additive feature requires a special supporting HDMI Cable Power cable and a supporting HDMI source device. The “active cable” can only be attached in one direction, however.
“One end of the cable is specifically labeled for attachment to the HDMI Source (transmitting) device, and the other end of the cable must be attached to the HDMI Sink (receiving) device,” the HDMI.org statement reads. If the cable is attached in reverse, no damage will occur, but the connection will not work.
To determine whether a source device supports HDMI Cable Power, the HDMI.org advises consumers to “check the source device’s specifications or feature labeling.”
The association said that HDMI cables with Cable Power will ship with an additional separate power connector for source devices that do not support the new feature.
The HDMI 2.1a spec was previously announced as supporting a new Source-Based Tone Mapping (SBTM) feature. The latest posting on the “amendment 1” states:
“In the case of the Ultra High Speed HDMI Cable, performance requirements are so high, it is likely that the only way to meet the Ultra High Speed HDMI requirements in cables longer than a few meters is through powered, active HDMI Cables. Therefore, HDMI Cable Power was added to help support the HDMI 2.1a specification’s higher speeds by providing power to those active cables which may need it to function correctly. While active HDMI Cables have previously been used extensively in professional markets, their use will now increase in the home whenever consumers need longer-length Ultra High Speed HDMI Cables.”
The announcement continues: “Connection is the same as attaching an ordinary, “wired” HDMI Cable, except that active cables can only be attached in one direction: One end of the cable is specifically labeled for attachment to the HDMI Source (transmitting) device, and the other end of the cable must be attached to the HDMI Sink (receiving) device. If the cable is attached in reverse, no damage will occur, but the connection will not work.
“HDMI Cables with HDMI Cable Power include a separate power connector for use with source devices that do not support the HDMI Cable Power feature. Typically, these connectors will be USB Micro-B or USB Type-C, but different power connector types may be used. As more and more source devices add support for HDMI Cable Power, these longer cables will deliver convenience in the living room along with reliable, high performance home theater audio video.”
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By Greg Tarr
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