Hi, actually, you may have heard, but HDMI carries power (5V) on pin 18, and the idea here is to take advantage of that power via this Micro-USB port. You could imagine taking advantage of it to charge your smartphone, but beware... we don't expect HDMI to give us more than 10 milliamps. And there again there are nuances, with the MHL 1 standard which is capable of delivering 0.5 A and MHL 2 and 3 of delivering 0.9 A (even so, with 5 V, modern smartphones will not manage to be recharged, at least not quickly).

Hello, this connector is apparently only for "just in case". For me, I have no problem with the connection without additional power supply on an old 17" Dell flat screen led. The picture is good, no shaking.