The HDMI interface was not designed to power external devices, but rather to supply sufficient power to complete the initial handshake, HDCP authentication and EDID Exchange. Whilst many source devices provide more than the specified 55mA to perform these functions, they do not always provide enough additional power to allow the operation of external HDMI accessories such as Active HDMI Cables, HDMI to VGA Converters and HDMI Fibre Optic Cables.

Connecting the HDMI Power Injector Cable overcomes this issue and allows you to provide additional power to such devices, by positioning the cable inline between the HDMI source and the HDMI Accessory and then connecting the USB cable to a USB port on your HDMI Source (PC with low power graphics card or Bluray player etc) or to an external USB power supply (not included).