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I do not see the issues noted: I do see another conflict that has been brewing here: - two wire adapters/plugs, vs. three or four wire plugs. I think the various standards for wall plugs around as rather
imbedded and we are not going to change that very fast. I have test equipment that
commonly comes with the three prong connector which appears to be the standard
desktop computer chassis input plug. Using that as a standard we already have
a rather common interface to the electrical supply world or the power input.
Yes this is my world. We need to focus on the standard for output. This is most
challenging regarding the power range for 1.3 to 130 watts. That is a huge
range and a one size fits all plug or connector is a bold expectation. At five
volts that is milliamps to 30 Amps. At 19 Volts we have more reason at the upper
end, 10 amps but even smaller at the lower end. I see a practical side to two adaptors, one up to five watts or
so limited to five volt devices and one that is larger with multiple outputs of
various amps, voltages or even multi-ranging based on rates of supply. This
cuts the small versus large price wars. James R. Johnson, P.E. Pacific Power From: upamd@xxxxxxxx
[mailto:upamd@xxxxxxxx] On Behalf Of Edgar Brown Per Hassel, I think we are _mostly_ in violent agreement. I now think
that an analog modality would be feasible and cost-effective, as long as it is
a simple/feature-less implementation. A good example is kelvin-sensing. As long
as there is trickle power, the adapter can sense the presence of a load and
slowly increase the voltage until the sensing lead reaches a specific voltage
range. That way the adapter does not need any further information from the
load. The adapter only has to track the feedback signal adjusting its output to
remain in the acceptable range. Alternatively, the current or impedance on the
'kelvin' lead could indicate the "power-class" of the load. Note that any analog DC alternative (that I can think of)
has the problem of guaranteeing that the adapter does not become a hazard when
two or more random terminals in the connector are shorted together. Regarding power, I agree on the approach of making the
marking presence and location a mandatory part of the standard. This can be
complemented with LED colors and patterns. A user could easily become
accustomed to an adapter's fast blinking red LED, just beside the power
sticker, indicating that it cannot provide enough power for the connected
device. (Or a steady yellow indicating that the user could be better served by
a higher-power adapter.) I do see another conflict that has been brewing here: - two wire adapters/plugs, vs. three or four wire plugs. Edgar On Jul 8, 2010, at 7:10 PM, Per Hassel Sørensen wrote:
Edgar, I
agree that it is detrimental if we have some various adapter classes, but: I believe
it is almost impossible to not have incompatible combinations of adapters and
devices due to power requirements. The biggest cost factor for a mains
powered adapter is the power rating. It is also a weight and size
factor affecting portability and usage. I don't think people will accept
cost, size or weight of a 130W UPADM adapter to power a device like a portable
radio or charge a micro RC model helicopter. I think this is
not a big issue if handled properly. With
a good UPADM standard, it should be the possible to use any UPADM adapter
as long as it supplies the minimum power needed for the device. Everybody
(Almost) will understand that adapters need to come in different sizes. This is
not difficult as long as we keep adapter power rating the only variable
the user has to think of. It could be part of the standard that
power rating of adapter and consumer is easy to locate, is concise and has
a common labeling. And imagine a sales situation where someone walks into
a store in need for an adapter: The 130W 'brick' will always work,
(un)fortunately (for the store), it is the most expensive one. To
save cost on the consumer side the UPAMD could support a basic analog
mode. Imagine having two separate communication wires in the UPAMD
cable. When in analog mode they are used for sensing a simple analog network in
the consumer. Certain properties (resistance, zener diode voltage etc.) is
detected by the adapter to select correct output voltage,
current limits etc. Further, as a transition solution, a UPAMD adapter
cable with built-in analog network could be built for a very low cost to be
used with legacy equipment lacking built-in UPAMD support. This way
existing equipment can use the new adapter. For
more advanced consumers the UPAMD would use the two communication wires
for duplex communication overlayed (or time multiplexed) on
analog voltage feedback (aka 'Kelvin clips') for reduced cable
cost, better regulation and other benefits as stated in my
previous mail. This
way a full digital communication is present in every UPAMD adapter from the
beginning, without requiring a major revision for purely analog devices. And every
UPAMD adapter will work with all devices, as long as the power requirements are
met as described above. Per
Hassel Fra: upamd@xxxxxxxx
på vegne av Edgar Brown Rene, I see two conflicting goals in removing communications from
the requirements: (1) universality (one adapter fits all) and (2) low-cost
(a.k.a. analog) simplicity. Although a properly designed analog solution can
nearly always be the lowest _manufacturing_ cost one. It would probably be the
most complicated in terms of flexibility. As an analog and digital designer, I
am always confronted on where each technology fits best. I can clearly remember
the cases in which, after a grueling analog design has been put together, I
have wished to have gone digital instead. While the converse is rarely true. These are the issues as I see them: - A single plug fits all: If a UPAMD plug is present in an
adapter and a device, we want the consumer to correctly assume that the two can
be plugged together. Having a class of adapters that would not power some
subset of devices would be very detrimental to this goal (this also applies to
power levels, B.T.W.). This is also one of the strongest arguments against the
highly non-standard and irritating family of barrel connectors. - Providing enough flexibility through analog means,
although possible, would _probably_ complicate the circuit enough that a
comparable digital solution would end up being cheaper in the short (and long)
term. (And clearly cheaper from a design stand point.) - A properly designed (and adopted) standard would create
industry demand for the right low-cost semiconductor solutions. As a sample,
take a look at the prevalence of ARM cores in TI's family of PMBus PWM power
controllers. An ARM core would be overkill for our intended application, but it
is not out of the question in the mid-term. A power supply that has to satisfy
multiple requirements, such as power-factor correction, low-power consumption,
stand-by modes, etc., presents enough functionality that an all-encompassing
integrated digital solution would probably be preferable. And while writing this I thought of a way to accomplish some
of the conflicting analog requirements. A simple feedback mechanism, in which
the device requests power from the UPAMD through a simple lower/higher analog
signal (essentially a slow remote regulation loop) could satisfy some of these
conflicting requirements. An AC signal (e.g., AM-modulated voltage feedback)
can close the device-adapter loop. Only requiring simple
diode/resistor/capacitor circuitry to extract the return feedback signal. And
this would not even require extra wires in the connector. This choice would
somewhat complicate any communications between adapter and device, but it still
can be done with decades-old modem technology. Regarding 'greening' technologies. Although it is true that
large equipment is the easiest target for conservation efforts, do not
underestimate the amount of power being wasted on tens of unused but plugged
adapters in each home and thousands in each office building. Also don't
underestimate that any progress towards these types of standard would also ease
the development of equivalent standards in directly-plugged AC devices. Any
progress to be made in removing power through greener adapters I believe to be
worthwhile. Especially in a standard that we hope would be still useful a few
decades into the future. Edgar Brown On Jul 7, 2010, at 4:51 AM, LEI / Rene Koch wrote:
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