The HDMI Forum has announced a new amendment to the HDMI 2.1a standard called HDMI Cable Power. With HDMI Cable Power support, active HDMI cables can be powered directly from the signal source without the need for a different power cable.
Due to their properties, high-bandwidth (48 Gbps) passive HDMI 2.1 cables cannot be very long. As a rule, such cables are limited to a length of 3 meters. To solve the problem, active HDMI cables are required, which are equipped with a special signal amplifier. It needs extra power to work. As a result, an active HDMI cable is additionally equipped with a USB connector through which power is supplied. Some active HDMI cables even come with complete power supplies.
The HDMI Cable Power specification to the HDMI 2.1a standard eliminates the need for an active cable to have an additional power connector. All the necessary cable takes through a single HDMI connector. Regular HDMI cables are designed to carry up to 50 mA. With HDMI Cable Power support, they can already transmit up to 300mA at 5V.
To use Cable Power, you must have an appropriately certified cable and a source device that supports this feature. The connection is the same as with a conventional passive HDMI cable. However, it is essential to remember that active cables only work in one direction, and when connecting, you need to be guided by the marks on the ends of the cable. You can connect them incorrectly without breaking anything. But there will be no benefit from such a connection since the Cable Power function simply will not work.
The new HDMI Cables natively supporting HDMI Cable Power will ship with separate USB Micro-B or USB Type-C connectors that can be used with source devices that do not support Cable Power.