Evaluation Engineering - 12

SWITCHING SYSTEMS

SPECIAL REPORT

BALANCING DENSITY
AND PERFORMANCE
TRADEOFFS
By Rick Nelson, Interim Chief Editor

Low- to medium-density switching
systems serve applications ranging
from aircraft development to automated
test, according to a selection of vendors
surveyed for this report. Read on to find
out what else they told us.

Emerging trends
What trends have you seen develop recently, and what trends do you expect to
develop soon in low/mid-density switching systems?
Bob Stasonis, technical product specialist, Pickering Interfaces: There really is
little new in terms of trends for low/middensity switching, although we have addressed one new market. Typically, if you
exclude high-voltage (standoff issues) and
high-current applications (relay size), low/
mid-density switches are specified for two
reasons-budget and performance. Let
me explain each separately. The budget
issue relates to paying for "just enough
test." In other words, I may never need a
greater switching capacity for my application and my budget is tight, so why buy
more switching than I need? If budget is
not an issue, you go for more switching
to future-proof the system.
In terms of performance, the higher
the frequency of your signals, the greater
possibility of lower isolation and higher
crosstalk in a higher density configuration. Wider spacing between components
makes it easier to design higher performance switching. As data rates get higher

EVALUATION ENGINEERING DECEMBER 2019

(for example, USB 1.0 was only 1.5
Mb/s, while USB 3.1 is 10 Gb/s)
greater attention must be paid to
the performance of the switching.
We recently had a cable-television
testing application that was failing
the MoCA (Multimedia over Coax
Alliance) signal due to excessive
crosstalk. Special switching that
was more of a mid-density was
designed to overcome this
limitation.
If you want to think of
this as a trend, the developments in low/mid-density
switching are being driven
by new relay technology that
is enabling higher density designs. The
technology that is allowing us to continue
to increase density in switch designs, including Pickering's 4-mm2 relays, results
in new definitions for what low/mid density is. In other words, what was medium
density two years ago is likely considered
low density now.
Jon Semancik, director of marketing,
Marvin Test Solutions: Lower I/O pincount applications typically drive low/
mid-density switching requirements, and
there really haven't been any significant
applications or industry trends emerging
specifically along these lines. Cost always
enters into the equation when specifying
a test system, and reducing the size of
the switch subsystem can help control
this; however, it is important to select an

Pickering Interfaces
PXIe-based USB hubs with
integrated switching.

architecture that can scale with
future demands to minimize the
financial impact of expansion
hardware and software.
Norton Alderson, VP of marketing,
Universal Switching Corp.: Universal
Switching has its roots in the ATE industry but over the last 27 years has branched
out into nearly every industry. This year we
received a new type of application where
in the development of an aircraft, the user
wanted to switch in various devices on to
a 1553 bus-loop. This automated the process of the client either physically connecting devices together with various cables
or using patch cords with a patch panel.
Automating this process eliminates mistakes, reduces wear on the devices, and
saves a tremendous amount of time. A
complete reconfigure of the devices takes
seconds to accomplish rather than hours.
This allows the user to quickly evaluate
different aircraft/device configurations
during the engineering phase.

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