CE Pro February 2022 - 26

Networking+Home Control
HDMI CORNER by DPL Labs
Active Devices Are Still
Out of Power Range
WHAT IS GOING ON WITH
super-expensive testing
that seems to be allowing
products to claim passing
certification even without
meeting the necessary power
requirements - particularly
active optical cables
(AOC) we've had in for
testing at DPL Labs? Maybe
they are just buying time
until the interface's power
specification changes over
perhaps by 2023. Still, what
does one do until then? For
starters, take a moment to
understand what the real
deal is here with power.
The HDMI interface has
onboard its multiple wire
configuration one that is
reserved for 5 volts. Over
time, this voltage level has
become a standard due to
its huge exposure in the
consumer electronics industry
with USB being the leading
driver. From the 5 volts,
other lower voltage levels
can be created via many
fantastic supply solutions in
the semiconductor world,
we use them all the time.
That being said, however,
the workable current needed
for most applications is
relatively high compared
to what's available on the
HDMI power bus.
In most applications,
power demands typically
hover around 200ma to
500ma (0.2 to 0.5 amps).
But the HDMI interface
26 | CE Pro February 2022
only has a total guaranteed
current of 55ma. I say
guaranteed because the
specification only requires
the source to have a minimum
of 55ma. That does not
mean source manufacturers
couldn't up that to 100ma
or even 200ma on their
own; it happens all the time.
The problem is that integrators
don't know this from
product to product - settop
boxes, Blu-ray disc players,
etc. are all over the map
when it comes to current
offerings. So, it is somewhat
of a crapshoot. But with
48G 8K transmission slowly
coming into view, the need
for active cable transmissions
will be common and
all will need some form of
supply voltage.
Let's crunch the numbers.
The HDMI bus' designated
5-volt wire is used to not
only flag the sink (display)
device it is attempting to
communicate with by way of
HotPlug but can also be employed
for internal circuitry
used to maintain the bus for
the entire system whether
the system is off or on.
The way it works, when
the system is in the power
off mode the current
requirement is 55ma. When
the system is in power on
mode this current number
can drop to only 5ma
according to the spec. So,
really, the installer has about
5ma at his or her disposal
to use for whatever they
may want or need when
the system is on or off. But
historically, getting anything
done at even 50ma
is near impossible. Should
the system require the full
50ma for normal operation,
it doesn't leave much room
to supply enough power to
an active device especially
when you consider current
demand when the system is
fully loaded and operating.
AOC hybrid products
have active circuits in both
the source and sink side of
the cable. The good thing
is that this technology has
experienced some major improvements
in lowering the
amount of current consumption,
but unfortunately it
still doesn't meet the power
consumption limits. Even if
you consider the power " on "
state as being your most important
function it still only
provides 50ma. DPL Labs has
seen AOC products come in
as high as 300ma and now
they are coming down to less
than 60ma in some cases
and as close as that is, it
does not make the numbers.
As mentioned, these low
current numbers on the bus
will eventually increase as
more power has been ruled
in but probably will not surface
for some time. For now,
when AV installations must
use legacy source hardware,
" Should the
system require
the full 50ma
for normal
operation, it
doesn't leave
much room to
supply enough
power to an
active device. "
pay extra attention. When
in doubt, some external
devices can be added, but
be careful since they are not
necessarily capable of delivering
full 48G throughput
for all four video channels.
Companies testing these
AOC products have the
option to use these external
devices and are included
with each DUT (Device Under
Test). Not only are they
used to supplement the
power to achieve these low
currents, but they are also
tested for all high-speed
video evaluation and analysis
guaranteeing each product's
performance with and
without an external device.
It may be a trial-and-error
procedure if you attempt to
do this on your own.
JEFF BOCCACCIO,
president of DPL Labs, can
be reached at info@dpllabs.
com, or visit dpllabs.com.
cepro.com
http://www.dpllabs.com http://www.cepro.com

CE Pro February 2022

Table of Contents for the Digital Edition of CE Pro February 2022

CE Pro February 2022 - Presentation Page
CE Pro February 2022 - Cover1
CE Pro February 2022 - Cover2
CE Pro February 2022 - 1
CE Pro February 2022 - 2
CE Pro February 2022 - 3
CE Pro February 2022 - 4
CE Pro February 2022 - 5
CE Pro February 2022 - 6
CE Pro February 2022 - 7
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CE Pro February 2022 - 64
CE Pro February 2022 - Cover3
CE Pro February 2022 - Cover4
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