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ens of billions of “things” are set
to be connected to the Internet
over the next few years, but not all will be
individual IP-addressable sensors. Many
will be gateways that concentrate data
received from arrays of devices via links
such as Bluetooth
®
or proprietary low-
power radio, or wired point-to-point or
fieldbus connections. With these devices
included, the Internet of Things (IoT)
could be gathering data from more than
a trillion sensors to be processed and
stored in The Cloud.
Much IoT design analysis is focused
on ultra-low-power design, enabling
endpoints such as smart sensors to run
for long periods powered by a battery or
by energy harvested from the ambient
environment. Gateway devices require
significantly more power than a small
battery or energy-harvesting system can
provide.
Unlike sensors, which must be placed in
specific locations, gateways allow more
flexibility to position the device near
a convenient source of power such as
an AC wall outlet. If an external power
adapter is used to provide the low-voltage
DC supply for the gateway, designers can
simplify the gateway’s internal circuitry
and outsource the responsibility to
comply with power safety and efficiency
standards to the adapter supplier.
Making Adapters More
Efficient
Designers of all sorts of OEM systems
have been choosing to power their
designs with an external adapter for
several decades now. In fact, adapters
have been so successful that researchers
as long ago as the 1990s foresaw a future
powered by billions of the devices. A 1998
study by Alan Meier of Lawrence Berkeley
National Laboratory (LBNL) estimated
that about 5% of total residential
electricity consumption in the US - worth
about $3 billion - was wasted by power
supplies while the connected equipment
is in standby mode. The percentage was
predicted to reach 30% within 20 years if
no action was taken.
The first mandatory energy-efficiency
specifications for external adapters came
into force in California in 2004. Similar
standards were adopted worldwide, and
became harmonized as the International
Energy Efficiency Marking Protocol for
External Power Supplies. Evolution of
the protocol has imposed increasingly
stringent limits on no-load power
consumption and minimum average
operating efficiency.
In 2014, the US Department of Energy
(DoE) announced that all external
power supplies (EPS) manufactured
after February 10 2016 and marketed
in the US must meet the new Level VI
efficiency specification. The EU and
other authorities, currently operating to
Level V specifications, are expected to
raise their own requirements to Level VI
soon, although none have yet announced
official regulations.
The new ruling applies to all external
power supplies, whether they are shipped
as standalone products or in the box with
OEM equipment such as notebook PCs,
T
New Adapter Regulations for a More
Efficient IoT
Jeff Schnabel, CUI
44 l New-Tech Magazine Europe