[Moved]: HDMI surge protection

[dharithothi]

Hello Guys,

I am having issue in HDMI interface failure due to surge. Currently I am using ESD protection IC TPD12S016 from TI. but this is for only ESD protection and can not provide Surge protection. I also searched surge protection chip for HDMI but I can't find proper protector of HDMI. As HDMI is highspeed interface normal surge protector is not recommended. So which take care should be done for surge protection on HDMI.???

 

[FvM]

Re: HDMI surge protection

I wonder according to which standard a HDMI interface is required to withstand surge events? Applying IEC 1000-4-5, no surge test is advised for data lines up to 10 m, up to 30 m under special circumstances.

I guess you'll have serious difficulties to achieve immunity for non-isolated high speed interfaces.

 

[dharithothi]

Re: HDMI surge protection

Hello FvM,

Can i try by providing EARTH to HDMI connector???

 

[westom]

Re: HDMI surge protection

Can i try by providing EARTH to HDMI connector???

Earthing the connection would make that connector a target. Surges hunt for earch ground. A surge incoming on AC main will hunt for and find earth ground outgoing via an HDMI port. Never address surges at the appliance. Always address a surge BEFORE it can enter a building.

Telephone and TV cable should already have that effective protection installed for free. That properly earth protection is why that surge is outgoing from an HDMI port. Address the typical incoming path - AC electric. No 'whole house' protector is required to be installed there. Best protection does not exist if you did not properly earth it.

BTW, earth ground is not that wall receptacle safety ground. Safety ground protects humans. Surge protection must connect low impedance (ie less than 3 meters) to earth ground. Then hundreds of thousands of joules are harmlessly absorbed outside. Then no surge current is inside hunting for earth ground destructively via all appliances - including dish washer and furnace.

 

[FvM]

It's not clear to me what kind of earthing is intended. Regularly, HDMI cable screen and connector case are connected to instrument ground. Surges won't be able to affect the signal lines. Instrument ground may be connected to protective earth, depending on the instrument design.

What's the test setup that causes HDMI interface failure?

 

[westom]

It's not clear to me what kind of earthing is intended. Regularly, HDMI cable screen and connector case are connected to instrument ground.

Instrument ground, digital ground, analog ground, chassis ground, and wall receptacle safety ground can be interconnected. And all are electrically different. Otherwise you could connect a lightning rod to any to protect the building.

Earth ground is completely and electrically different from all. Now reread that previous post. That reply can only exist if statements in a previous post were ignored.

Surge protection is how a surge connects low impedance (ie less than 3 meters) to earth ground. That is not safety (protective or equipment) ground in a wall receptacle. Especially important is every number - ie 3 meters. Part of a path that also goes maybe another four miles through earth.

A surge incoming on AC mains is directly connected to every signal wire, instrument ground and every wire in an HDMI port. Otherwise you can say how something not 'blocked' by three kilometers of sky is 'blocked by 1 centimeter electrical parts.

Protection is always about a path used by a surge to connect to earth ground. An to earthborne charges some four miles distant. Define how instrument ground or wall receptacle safety ground somehow 'blocks' or 'absorbs' hundreds of thousand of joules. Those numbers make obvious that any 'magic' attachment does not and cannot protect from a transient that typically damages HDMI ports.

 

[FvM]

I notice a partly different usage of terms. What you call "safety ground" is named PE (protective earth) in international standards.

Protection is always about a path used by a surge to connect to earth ground.

That's true as far as building or plant wide surge protection in power distribution and communication lines is addressed.

Nevertheless there are surge protection standards for instruments (e.g. in said IEC 1000-4-5) which deal with the surges bypassing the first protection levels. Conducting away surges to a low impedance earth ground isn't an option on this level.

A surge incoming on AC mains is directly connected to every signal wire, instrument ground and every wire in an HDMI port. Otherwise you can say how something not 'blocked' by three kilometers of sky is 'blocked by 1 centimeter electrical parts.

As for the surge voltages that are discussed in instrument level surge protection (e.g. up to 4 kV), they can be blocked by 1 cm electrical parts under circumstances. A surge "incoming on AC mains" is not necessarily converted to a large differential voltage inside the HDMI circuit. The major problem is probably that it causes a common mode current along the HDMI interconnect which in turn generates a possibly destructive differential voltage in the interface.

We need to know the OP's test setup to discuss the details.

 

[westom]

Nevertheless there are surge protection standards for instruments (e.g. in said IEC 1000-4-5) which deal with the surges bypassing the first protection levels.

Which means we are discussing a transient that exists before it is even on wires that provide electricity to a building. Obviously IEC1000-4-5 is only about an item. It is only a tiny part of a bigger picture.

To protect any appliance from a surge that can easily blow through that 4000 volt protection means addressing that surge where it is most easily eliminated before it can enter a building. That solution is typically located at a service entrance and always with a low impedance (ie less than 3 meter) connection to single point earth ground. Only then is protection defined by IEC1000-4-5 not overwhelmed.

Does not matter if every other ground connects to that earth ground. Those are irrelevant. Impedance of that connection must be low. That connection must have no sharp bends. It cannot be inside metallic conduit. It is separated as much as possible from other non-grounding wires. It must have no splices. It must have no sharp bends. It must be low impedance.

A protector is only as effective as its earth ground - electrodes in earth. Should damage happen, an investigation starts by locating a human mistake that made damage possible. That starts at the item that must always exist to have effective protection - single point earth ground and connections to it.

Best protection on a TV cable is a hardwire direct to that earth ground. A protector only does what a direct hardwire does better. Effective protectors are only connecting devices to what defines protection. To what harmlessly dissipates hundreds of thousands of joules. That is an always required single point earth ground.

Classic example of HDMI port failure is a surge incoming on AC main. And outgoing to earth via some other path. HDMI port is a classic outgoing and destructive path to earth via its cable or satellite dish connection. That connection path can include any signal wire, analog, instrument, or digital ground inside electronics, and any 4000 volt protector. It is the nature of a classically destructive surge; that is a current source.

Protection is always about where hundreds of thousands of joules are harmlessly absorbed. A protector is only as effective as the quality of and connection to its earth ground.

Concepts that define protection of appliances inside a building were demonstrated by protection of that building - when using a lightning rod. In every case, protection is defined by what harmlessly absorbs even hundreds of thousands of joules. Best protection for HDMI ports exists where that surge might enter a building. A solution that typically costs about $1 per protected appliance.

BTW, protective ground is about a resistance connection. For surge protection, impedance (not resistance) is the critical parameter. So we discuss earth ground - a subset of what is described as protective ground. A low impedance connection is always possible. Why were we always able to achieve one? It is required for effective protection even of the HDMI port.