CE Pro October 2023 - 22

Networking+Home Control
HDMI CORNER by DPL Labs
HDMI Supply Power Continues
to Haunt Integrators
LAST MONTH, we reported
an incident that occurred
with an assortment of
high-performance equipment
having trouble operating
up to full potential when
using AOC (active optical
cable) devices. This month,
let's continue with more
discoveries involving power
management.
Measuring 18 diff erent
branded AOC devices at
DPL Labs proved that none
of these samples met HDMI
power current limits. This
is serious and can leave an
integrator walking in circles
searching for the problem,
not only during installation
but well after the project is
complete.
The interface has power
limitations designed specifically
for its own operation
when working with only
passive cable products.
There is little left after the
system initializes and starts
up. It's designed to generate
a 5-volt DC output
to be routed to the sink
device and deliver a minimum
of 50mA (.05 Amps).
This small amount does not
leave much energy left to
operate other electronic
devices on the same bus.
But again, it was never
intended to be used this
way. It is designed for only
one purpose and that is to
support the HDMI system
environment, that's all.
22 | CE Pro October 2023
As we conveyed, when
you throw in any active
cable devices, more power
is required to operate these
types of cable products.
Now, with so many AOC
devices in service, test
sampling can be achieved
proving that AOC power
consumption, in most cases,
was causing interoperability
issues in the fi eld.
supply at least 50mA to
earn certifi cation. This also
means that any source
product can provide more
power should companies
want to invest in their device's
built-in power supply.
This is why a fair amount
of devices function when
fi rst put into service. But
the rules have changed a
bit as we've entered into
As we've entered into full 8K
and 10K resolutions, these AOC
devices can pull even more
power, starving its supply bus
and causing failures to occur.
These power demands
vary from one AOC to
another. DPL found that out
of 18 AOC products, there
were fi ve levels of power
consumption measured, all
being over HDMI minimums.
As an example, there were
some AOCs that operated
at a reasonable 65mA. For
sure, they still breached
HDMI limits, but it at least
made a good attempt
compared with others that
had demands of better than
200mA.
Keep in mind that every
source product (AVR,
switch, set-top box, etc.) is
assigned the job of providing
this power to the bus.
Remember, under HDMI
limits, every source must
full 8K and 10K resolutions.
These AOC devices can pull
even more power, starving
its supply bus and causing
failures to occur.
One such device that
was tested reinforced this
claim. It was a simple 8K 1x3
switch. Its power output
was adequate at 100mA. It
had the best 8K and 10K response
out of all the other
contenders. Then, after 10
minutes of cable testing the
device, went dead for no
perceptible reason. Digging
in to determine what had
occurred, it became evident
that one AOC that DPL
tested demanded 195mA to
function. This high-current
demand caused the internal
power supply in the switch
to overheat and eventually
took out the supply.
It was not the fault of the
switch, but the high current
demand of the AOC. This
is something that any integrator
should be cautious of
- it's kind of like a delayed
fuse reaction that can
eventually open and that
system you installed a year
ago dies.
DPL Labs added cable
current testing to its Argumentative
Matrix Testing
Platform some time ago
recognizing these power
supply shortfalls. Every AOC
tested under the Matrix
Test Platform uses the manufacturer's
supplemental
external power to alleviate
these issues. If you aren't
sure, contact the cable
manufacturer directly to
help limit your liability.
JEFF BOCCACCIO,
president of DPL Labs, can
be reached at info@dpllabs.
com, or visit dpllabs.com.
CORRECTION:
In August's HDMI Corner,
the included image should
be this Murideo SIXG-8K
Signal Generator.
cepro.com
http://www.dpllabs.com http://www.cepro.com
CE Pro October 2023

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