An amendment to the HDMI 2.1a specification was announced yesterday which introduces a new feature called HDMI Cable Power, allowing users to use much longer HDMI cables than those currently supported, without the need for a power connector. separate power supply.
Power over HDMI cable will overcome the limitation of fixed rate link signaling system of HDMI 2.1, which provides high-speed, high-bandwidth signals but can only be kept over short distances, which means that the Passive cables are limited to a few meters in length.
Previously, the only way to overcome this constraint was to use active HDMI cables, which use an amplifier to amplify the signal allowing it to be sustained over longer distances without degradation, and commonly found in professional environments.
While active HDMI cables require a separate power supply powered by an external source, power-over-HDMI cables can draw up to 300mA of a source’s 5V power supply directly from the HDMI connector, which allows for less convoluted cables in home theater systems.
However, like active HDMI cables, HDMI power cables will be unidirectional, with a specified source and output. According to the HDMI website (opens in a new tab)“One end of the cable is specifically labeled for connection to the HDMI Source (transmit) device, and the other end of the cable should be connected to the HDMI Sink (receive) device. If the cable is connected to the upside down, no damage will occur, but the connection will not work.”
Power over HDMI will be available for all categories of HDMI cables, but for ARC/eARC support you’ll want to look for cables labeled as Ultra High Speed HDMI Cable, Premium High Speed HDMI Cable with Ethernet, High speed HDMI cable with Ethernet or standard HDMI cable with Ethernet.
To use Power over HDMI, you need both an HDMI cable and an HDMI source device that supports the function. We haven’t seen any announced products that include it yet, but it’s worth noting that new HDMI cables with Cable Power will come with a separate power connector, normally a USB Micro-B or Type-C, for use with an incompatible source. devices.
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