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Test
Engineers may be finding it more and more difficult to keep up with
the growing and changing demands created by the never ending craze for
“High(er) Tech” power supplies.
I suspect that to the volume manufacturers of power supplies,
the battle seems unending. There
is, of course, the always-present demand for greater IC integration,
involving higher component and power density.
Notwithstanding
these expected and ongoing developments with product design and
performance requirements, there’s a fairly new “trick” available
for helping engineers to better accomplish these goals.
The “trick” is to make power supplies that “talk” as
well as “listen”. Communication
“enhancements” enable the power supply to assume more
responsibility for monitoring and governing its own “health”.
As
Applications Engineering Manager for Autotest Company, I see a lot of
new stuff – and over the years have witnessed the migration of many
new technologies into the world of power supplies.
Our Functional ATE systems have always required specialized Unit
Under Test (UUT) communications. These needs have been
addressed with a variety of solutions involving protocols, busses, and
advanced levels of component integration and complexity. For some high tech Department of Defense (DOD) products, we
employed what have become now proven and accepted solutions such as
RS232, RS 485, IEEE 802.3 Ethernet, IEEE 488, MIL 1553, I2C,
and many others. These
technologies can simply read a serial number from a register or
actually direct the Power Supply through a complete routine of
calibration and internal verification.
In such cases, the ATE’s hardware or equipment
responsibilities may be simple, but the communication process,
coordination and test sequencing can be quite complex.
Along
with the continuing trend for making the power supplies more
technologically capable, powerful, versatile and complex there’s a
rapidly expanding area of expansion in the field of self-diagnostics
and maintenance. We
are also seeing more and more the use of processors in power supplies
… to make them more versatile and flexible for diverse applications.
A typical application is with power supplies that are employed
as sub-systems of a more complex DOD product.
These power supplies are often asked to provide much more than
just delivering system power. They
are often integrated and designed to monitor, react and respond to
variable and changing requirements of a much more complex system.
At
Autotest, we first addressed
these more complex phenomena with the introduction of our UPS ATE.
The Uninterruptible
Power
Supply (UPS), by design, has a responsibility to
communicate with the computer to which it is delivering backup power.
UPS manufacturers, taking advantage of the need for UPSs to
have communication and processing ability decided to let the processor
do other things as well, like calibrate output parameters and provide
functional controls for supporting them.
Built In Test
(BIT) functionality is becoming more common with power supplies,
making them capable of being programmed to sequence through an
internally controlled test process and to report the results. With the integration of a processor and a bi-directional,
software-controlled communication bus to manage this process,
significant additional diagnostics and information can be provided.
The
latest communication trend in communications for commercial power
supplies is in the application of the IIC
Bus (Inter-Integrated
Circuit), or I2C
as it has come to be called. The
I2C Bus is an
essentially a two-wire, low to medium speed, communication bus
developed by Philips Semiconductors in the early 1980s.
It was created to provide a low-cost chip-to-chip communication
links for such things as volume and contrast controls in radios and
televisions. Over the past two decades, the I2C
has expanded its communications role to include power supplies.
So
how do Power Supply ATE manufacturers, such as Autotest,
address the changing needs of the Test Engineer? Communication has
always been an integral part of Autotest’s ATEs.
We use IEEE 488 extensively to control instrumentation, making
communication integral with all our systems.
Our open-ended software and language simplifies development of
Windows supported communication as an inherent function of test
programs for the UUT.
Perhaps our greatest challenge has been in developing the
language library to simplify the process of building flexible and
comprehensive routines into tests.
The I2C
posed a challenge in that regard.
A commercially available PC bus controller, however, provided a
simple solution for adapting the I2C
to developing hardware and software integration for controlling
communication as a part of testing the power supply.
Our APG for
Windows™ software, implementing and integrating new protocols
and busses, has provided test engineers with an automated test
programming and system control environment tailored to the needs of
most any Power Supply. It allows a Test Engineer to design simple solutions for
complex routines for engaging a power supply to whatever type of
interaction may be required.
In
essence, the marriage between power supplies and functional testing is
a longstanding and always developing relationship.
To coin a proven metaphor, “the key to any good marriage is
communication.”
Jim Pennington, Applications Engineering Manager- AUTOTEST Company
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