# HDMI EMI woes: cable

#### morzh

Joined Jan 18, 2017
29
It seems as my device is currently failing Radiated EMI certs when the HDMI cable is plugged in. Even Ferrites don't help much, according to the tech who tested it.
We have supplied thecable and it is your standard inexpensive 6' cable

I've done some reading on the issue and it seems like HDMI cables are a known EMI offenders' category.
I have also looked at the PCB remedies and I have found none: it does not look as if anyone uses any CM chokes such as they use for USB and such on HDMI lines. All I see is ESD protection which I have.

So, what I am looking for is:

1. A cable (6' is ok) reommendation by name: a know good EMI performer.
2. Any known working solutions that can be put on PCB to attenuate any intererence that would come out of HDMI cable.

Any help is greatly appreciated.

Thanks

Mike

#### crutschow

Joined Mar 14, 2008
27,232
Is the cable shielded?

Perhaps a cable with ferrite EMI suppressors at both ends, such as this, would work, or is that what the tech tried?

Is it required that you supply the cable with the device?

#### morzh

Joined Jan 18, 2017
29
Crutcschow

Thanks for the input.
No, we do not supply the cable, but as we were explained, if we have the port, it needs to be plugged into and then tested for at least the EMI, and then preferably for EFT/immunity etc.
The rest of the cables seems to behave; it is the HDMI that does not. We sent them what we had on hands; Personally I have never certified anything with HDMI and so I have no experience in dealing with it. I do understand what can go wrong, I found two articles bashing HDMI cables for being some of the worst offenders, but the only article that lists some good cables, lists those that are only sold in Japan/Vietnam or in the UK. Not here. Tried to look by names.

PS.. Took a look at the cable. Well...it is under $5 and with two ferrites it does not give me a whole lot of confidence about the shileding of it, else why the ferrites.....the cables listed in that arrticle by major companies like Sony etc start from$50 and some are \$300.

#### crutschow

Joined Mar 14, 2008
27,232
If it's radiated EMI that's a problem, then you may have to buy a good, shielded cable.
Ferrite suppressors are likely more for conducted EMI.

I'm not sure how you are expected to meet EMI requirements with a cable, when you don't supply the cable with the device.
A customer supplied cable would then likely not meet the EMI requirements.

#### ci139

Joined Jul 11, 2016
1,696