The Tributaries USB-VI, HDMI Voltage Inserter was designed to solve the problem of signal drop-out due to insufficient current from the HDMI source component. The HDMi® Specification requires a source to provide a stable 5VDC with a minimum output current of 55mA. Voltage from the source turns on microcontrollers in the sink device and allows the sink to return the 5VDC via the Hot Plug Detect line. The DDC communicates the EDID information and then the HDCP handshake takes place. This handshake is the gatekeeper for the entire HDMI signal. Not only is this required on start-up, but authentication is repeated continuously; if there is an error in this communication the system will not operate properly. These errors will cause flashing images from a HDCP errors, distorted video related to EDID or even complete loss of the image caused by HPD failure.
What causes 5-volt line instability? A source may have been poorly designed with insufficient voltage, or an HDMI cable is too thin causing excessive losses on the 5-volt line. The addition of bus-powered accessories like extenders and active HDMI cables that harvest power from the 5-volt line to power their on-board circuitry will also draw down the 5-volt line. HDMI was never designed to support bus-powered accessories.
To eliminate the possibility of a low voltage failure, Tributaries USB-VI features a Low-Voltage Protection (LVP) circuit. The circuit automatically activates if the source component’s output voltage falls below HDMI’s minimum operational voltage. Additionally, LVP will block reverse current flow that could potentially damage the source.