Since the HDMI voltage specification allows for the output port voltage to be between 4.8 V–5.3 V, there is the possibility that the downstream source is a higher voltage than the upstream source. One condition that can arise is a reverse current condition. If two HDMI sources are accidentally connected together, the system must protect against any damage to either output. The 5 V HDMI source needs to be regulated such that if the output line is shorted anywhere to GND, the device can protect the system from the overcurrent event. If the output is not regulated, a short in the cable can cause excessive heat dissipation that can damage the system and create a fire hazard. Depending on whether the HDMI source is connected to a source or a sink, certain transient events can arise.ĭuring the event that the output is connected to an HDMI sink, a potential short can occur along the output path. The 5 V power rail must be protected, whether connected to a source or a sink. If two HDMI sinks are connected together with a single cable, no damage can occur to either of the sinks.īased on these requirements, an ordinary 5 V regulated supply cannot be used. If two HDMI sources are connected together with a single cable, no damage can occur to either of the sources. No damage to the HDMI source or sink can result from the shorting of any combination of signals on any connector. ![]() Not draw more than 55 mA from the power signal when powered onĪssume any voltage within 4.7 V and 5.3 V indicates a source is connected. Shorting two HDMI Sources together shall not result in any damage.Short Circuit Current: no more than 0.5 A.Output voltage: 4.8 Vmin, 5.3 Vmax – In some case 5.3V may be ideal for longer cable runs to compensate for voltage attenuation over longer distances.The basic requirements for an HDMI source are: The HDMI 2.1 spec provides full detail of the 5 V regulation requirements. In order to ensure a robust HDMI power design, the power rail needs to be regulated in the event of a transient condition. The same applies to Fiber HDMI Cables which cannot be tested by certain HDMI Testers since they do not follow the 19 to 19 pin rule as with standard copper HDMI Cables. Copper HDMI Cables with a Booster / Equalizer is unidirectional (Indicated on Cable with Source / Display per Head) and some HDMI Tester channel tests may fail on a working cable. ![]() In general Bi-Directional copper HDMI Cables WITHOUT a built-in HDMI Booster / Equalizer can be tested with a HDMI Tester. HDMI Couplers in general are used on short distances and on long distances rather use an HDMI Equalizer / Booster. Using ANY additional contact points such as a HDMI Coupler can reduce HDMI Voltage and results in no signal transmitted. Long Cable runs can influence voltage transmission if the source voltage are too low and maximum cable runs will differ from one HDMI port to another due to small HDMI Voltage fluctuations. The HDMI Spec allows a tolerance of ☐.3 Volt in the spec as per picture below and will sync between 4.7v to 5.3v. HDMI Ports must be designed on the 5 Volt DC Specification on Pin 18 (Orange Wire but wire color differs from some manufacturer). HDMI has emerged as a standard for high-definition audio and video transmission, and has increased in popularity on platforms such as the following:Īs multimedia content has grown in popularity, HDMI hardware requirements have been included to ensure that data/power remains within regulation. HDMI Specifications and Technical Info | HDMI Voltages, HDMI Wire Layout, HDMI Channels DDC, TMDS and CEC Introduction
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