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EEWeb.c
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April 3, 20
Dave BaarmanFulton Innovation
Electrical Engineering Commun
EEWeb
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TABLE OF CONTENTS
Dave Baarman 4FULTON INNOVATION
Featured Products 9
Understanding Wireless Power - Part IBY DAVE BAARMAN AND JOSHUA SCHWANNECKE WITH FULTON INNOVATION
A Simple Circuit to Generate Plus 18And Minus Supplies Using a Boost RegulatorBY DON LAFONTAINE WITH INTERSIL
RTZ - Return to Zero Comic 23
Interview with Dave Baarman - Director of Advanced Technologies
With differing perceptions of wireless power demands among developers and consumers, itsimportant to find common ground for future wireless power solutions.
See how using a boost converter can help you get larger supplies of both positive and negativevoltages within your circuit.
11
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INTERVIEW
Fulton Innovationwater treatment system to eliminate6-log reduction or 8-log reductionof bacteria and viruses. It ended
up becoming a flagship product for
Amway.
From developing that water
treatment system, we created a very
unique wireless power system that
had a lot of versatility and was highlyresonant in the way that it would
adapt and respond to environmental
changes like temperature, space
and pressure. It was then that we
realized we really had a winning
product.
Can you tell us more aboutthe 400 patents you hold inwireless power technology?
We began developing the watertreatment system and the wireless
power system about 15 years ago
and we saw a very open white-
space of intellectual property
in the patenting world. So we
started patenting back then on
this technology, and really havent
stopped since. Actually, as it sits
DaveBaarman
Dave Baarman - Director of Advanced Technologies
How did you get into electricalengineering and when didyou start?
I always wanted to be an engineer.
Much of my purpose revolves
around being someone innovative
and who can develop new products.
I am very interested in research and
developmentmy first job was
actually in automotive research anddevelopment.
I also have a very entrepreneurial
mind. I started my own business,
sold it, and became a consultant.
I later got hired by Amway as a
consultant to provide wireless
power to a water treatment system.
Out of that relationship, the eSpring
water treatment system was born.
We created a wireless-powered
lamp system to be dropped into the
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INTERVIEW
right now, we have a portfolio of over
700 patents pending or granted in
just the wireless power space.
Can you tell us about beinga founding member of theWireless Power Consortium?
The goal of the Wireless Power
Consortium is to establish Qi
(pronounced chee) as the global
standard for power rechargeable
electronic products. It has more
than 100 members including
industry leaders in mobile phones,
consumer electronics, batteries,
semiconductors, components,
wireless power technology, andinfrastructure such as wireless
operators, furniture and automotive
parts companies.
Some member companies include
Motorola, Samsung, Philips, Verizon
Wireless, Texas Instruments, LG
Electronics and many more. A full
list of member companies can be
found here.
Fulton and the WPC believethat global standards are a vital
step in driving widespread
consumer adoption of wireless
power, and opens up the door
for full interoperability between
device manufacturers and OEMs
worldwide. Globally recognized
standards give consumers
confidence that their purchases
will work with compatible devices,
regardless of the brand.
How does Qi certicationwork?
We do Qi precertification for our
partners. The actual certification
is done by laboratories that are set
up to do this type of testing through
the WPC. It works out pretty nicely
because once you become certified,
they are deemed as interoperable,
and you become part of the WPC
and can put the Qi logo on your
products, just like Bluetooth or Wi-
Fi.
Can you tell us more aboutFulton Innovation and thetechnology it is developing?
Fulton Innovations goal is to
commercializing new and innovative
technologies that improve the way
we live, work, and play. Fulton
is working with a wide range of
industry-leading companies to
integrate wireless power technologyinto infrastructure and electronic
devices enabling consumers to live
a truly wireless life. Fulton Innovation
was established in 2006 to advance
wireless power technology, which
was first developed in 1998 by
parent company Alticor for its
eSpring water purification system.
The technology was further
developed, branded, and officially
launched as eCoupled technologyin 2007. Fulton licenses its eCoupled
technology to manufacturers so they
can incorporate eCoupled into their
products.
Can you tell us about theeCoupled intelligent wirelesspower project?
eCoupled technology is intelligent
wireless power based on inductive
coupling that allows for safe andefficient power transfer without
wires. eCoupled technology is
based on the principle of near-
field resonant magnetic induction.
With magnetic induction, electricity
travels via magnetic fields instead
of through a physical connection
of conductive materials like those
found in a traditional power cord.
Wireless power requires two coils:
a power supply coil (usually in a
surface or pad) and a receiving coil
(in a device). A shared or coupledelectromagnetic field is generated
when the power supply and
receiving coils are positioned near
each other, which then wirelessly
transfers power to or charges the
device.
eCoupled technology uses this
concept to eliminate the need
for power cords. It creates an
electromagnetic conduit, combined
with an intelligent control system
that constantly monitors the power
flow to ensure optimal efficiency
and safety.
How did you and FultonInnovation get involved in thisproject?
Fulton Innovation originally
developed the concept of eCoupled
wireless power in 1998 to solve a very
real problemfinding a safe way topower a UV lamp in a water purifier.
It was then that Fulton realized the
true potential of wireless power and
its broad applicability to virtually
any electronic power system. Since
then, Fulton has enhanced and
developed the technology and is
dedicated to commercializing new
and innovative implementations of
wireless power that improve the
way we live, work, and play.
How has this technology hada signicant impact on thewireless power industry?
The Qi global low-power standard,
set by the Wireless Power
Consortium (WPC), includes
elements of eCoupled technology.
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INTERVIEW
The Qi standard ensures full
interoperability between devices
and transmitters, regardless
of brand. The Qi standard
gives consumers flexibility and
confidence in their technology
purchase. Today, there are more
than 100 Qi-certified devices on
the market worldwide and the list
is growing rapidly. Fulton, as a
founding member of the WPC, is
committed to advancing Qi as the
standard with manufacturers and
consumers to encourage wireless
power industry growth.
What Fulton Innovation clientsare using this technology?
Fultons technology has been
incorporated into scores of products
from various manufacturers
around the world. You can see
our technology in the following
products:
Amway eSpring waterpurification system
Samsung Droid Charge
Motorola Droid 3
Motorola Droid Bionic
LG Revolution
HTC Thunderbolt
HTC Rezound
HTC Incredible 2
LG Charging Pad
Pantech Breakout
Motorola Droid 4
Does your licensing involveproviding a developmentplatform for users to start usingthe eCoupled technology?
This is a new science based on
old physics. It has a new twist:
multidimensional control. This
means that we are maximizing
physics in order to adapt to varying
environmental conditions. So, when
Fulton Innovationsgoal is to
commercialize newand innovative
technologies that
improve the way welive, work, and play.
we partner with a company, it
is a true collaboration. What we
are really selling is not just a
technology; we are selling that
knowledge to bring our partners
up to speed to understand the
state-of-the-art in a particular
technological realm. We do this tocontribute to the understanding of
state-of-the-art models, tools and
equipment, space and relationships
and electromagnetic fields and
materials that help users see things
in a dynamic environment that were
not previously possible.
Our patents are a progression of that
knowledge, and our relationships
are a technology transfer ofthat knowledge into a physical
embodiment that enhances our
customers products.
Are there any certicationrequirements for productsto make sure there isnt anyinterference with the system?
There are FCC, CISPR and IEC
requirements associated with any
electronics design. What weve
done with the WPC is set up under
a specific band where we have
reference designs to meet the
considerations and requirements
that exist for various products.
With the WPC, weve actually
selected a specific frequency
range in order to be able to meet
the regulatory requirements for
SAR exposure and insure that any
products using the Qi standard
are able to pass the strictest safety
regulations. You can do some
very interesting things balancingin between ICNIRP exposure
guidelines. Our range allows us to
do everything in the power range
of automobiles all the way down to
printed electronics.
Is that safe?
Just to give you an idea, a hairdryer
generates more radiation than our
power systems.
How far away can a devicebe and still remain efcientwith power transfer?
We can do relatively huge distances
and still efficiently transfer wireless
power. In space, you could do some
very large distances. In a room with
people in it, however, you are limited
by SAR exposure and ICNIRP
guidelines. We dont like to do huge
distances in rooms because of the
exposure to humans, so we have
made a considerable effort to limit
the distance between the appliance
and the wireless power supply.
We like the distance to be inches
rather than feet. Although we have
the ability, we have still chosen to
try and limit the distances to limit
exposure.
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INTERVIEW
Are you able to designdirectional antennas tocentralize where the power isbeing transferred?
We have done some very interesting
work with shaping electromagnetic
fields. We call it selective saturation.
We can actually put a radiator in a
table and put laminate over that
table with a shielding material.
Then selectively, wherever you
place your device, the field is
opened to transfer power through
the shielding material. It is very
interesting because it allows for the
opening of virtual holes where you
want the power to be transferred.
This year at the 2012 International
Consumer Electronics Show (CES),
we showed power through metal.
We have designed an aluminum
enclosure, and you can actually
set your electronics on top of that
product and it will charge.
Do you help clients designand incorporate yourtechnology into theirproducts?
Typically, yes. However, the process
varies with each partner. Using
a cell phone manufacturer as an
example, we may or may not go
through the process of using a
license agreement because the
client company might buy the
semiconductors from another
company (e.g., Texas Instruments)
that is already a licensee of ours.The manufacturer might want to go
through the process on its own and
use parts from other companies, but
still enlist our help with the product
to make the design meet certain
specifications and standards like
size and efficiency. There also
might be additional twists to the
manufacturers desires such as
incorporating another trademarked
feature into the design.
We then work together with the
manufacturer to model, design,test, validate and make sure it is Qi
compatible with the WPC. Doing all
of these things is what allows other
companies to use our technology in
their products.
Where can the eCoupledtechnology be used?
There are almost no limits to where
eCoupled can be used. Anywhere
theres a traditional power cable,eCoupled can certainly replace
it. We have shown examples of
eCoupled in everything from kitchen
appliances to vehicles. At last years
Consumer Electronics Show, we
demonstrated wirelessly charging
a Tesla Roadster electric vehicle.
eCoupled is flexible enough to be
used in packaging or publishing.
Using printed electronics, weve
shown how wireless power canbe incorporated into packaging
(we lit a cereal box so it flashed
on a supermarket shelf), and at
CES this year well be showing
a similar example with a copy of
Entertainment Weeklythat lights up
and flashes while it sits on a stand.
Regarding the technology,what frequency do youtypically use to transmit
power?
The technology is frequency-
agnostic, which means that we
can really tune to any frequency
and utilize and maximize the
relationships between transmitters
and receivers.
We can do that dynamically at
about any frequency range, but
with the WPC we operate between
80 250kHz. We have done that
very specifically for very specific
reasons.
What are you doing froma marketing standpoint toconvince companies toincorporate this technologyinto their next devices?
Ten years ago, when we were
pitching the capabilities of wireless
power, the reactions were, Its
impossible, It cant be done.
People thought it would be
inefficient and extremely expensive.Today, while it is a robust power
supply, it is also more convenient
to the consumer--it gets rid of a top-
ten warranty and reliability issue
by eliminating cords and cables
that usually break, and it can be
designed in ways that simply
replace the current power supply
and power management at very
little additional cost, regardless of
the power level.
It has been a long road getting
the consensus and understanding
within the electronics arena. But we
have been successfully doing it with
over 100 companies in the WPC,
and are finally nearing the tipping
point where people are realizing the
value in this technology.
What is the overall target
for Fulton Innovation for thewireless power industry?
We want wireless power to become
ubiquitous. Wed like to remove the
final cable (power) so we can enjoy
a truly wireless, mobile lifestyle.
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3-W Class-D Amplier With Smart Gain
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Wireless power is transitioning
from a technology to an industry.
Many questions ranging from whatconsumers really expect to which
technology is the safest and most
efficient solution are generating
an increasing amount of debate
as proprietary products come
to market and a wireless power
standard is introduced. As wireless
power reaches a tipping point,
it is important that developers
and consumers alike understand
the realities of the different
technological approaches
especially the safety and efficiency
concerns surrounding themand
the current and future states of the
technology as it gains momentum.
EXECUTIVE SUMMARY
Research has shown that wireless
power is one of the most attractive
new technologies to consumers.
However, there are misconceptionsin the media and the marketplace
about what consumers really expect
from the technology. In order for
the industry to fully develop and
reach mass adoption, there needs
to be a fuller understanding of the
different embodiments of wireless
power technology, as well as
clearer definitions of efficiency
(in particular, how efficiency is
measured), safety and the different
consumer embodiments of the
technology, including pad and
adapter solutions and a wireless
power specification.
Given these considerations
the viability of the technology
and the growing wireless power
industryit has become necessary
to collectively understand and
educate developers and consumers
and collaborate to create the bestavailable solution for today and
best position wireless power for its
future.
UNDERSTANDING
WHAT CONSUMERS
REALLY EXPECT
Research has shown that a desire
to simplify powering and charging
experiences and add a new level
of convenience to everyday life are
driving the consumer expectation
for wireless power. As the latest
wave of wireless power products
enter the marketplace and the
viability of the technology expands
into industry, a need to address the
understanding of wireless power
and how it will be incorporated into
Dave BaarmanDirector OfAdvanced Technologies
UnderstandingWirelessPowerPART 1
Joshua SchwanneckeResearchScientist
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TECHNICAL ARTICLE
everyday life has also arisen.
There has been a level of
misunderstanding about what
the consumer really wants and
needs. Research has shown that ifconsumers knew that an integrated
wireless power solution was going
to be offered in the future, they would
support a pad and adapter solution
today. Nearly half of consumers
surveyed indicated that they would
wait two years for a product if they
could have the technology built
into electronic devices. Still, about
one-third would be willing to buy
adapters, and about one-quarterwould buy the standalone charger
(pad) and use them until they
replace their devices with ones with
embedded technology [1].
However, this research also
indicates that there is a specific
price point that, once exceeded, no
longer makes the adaptive solution
attractive, even to early adopters.
Also, given the size of the adapter
market in light of the larger pictureof all consumer electronics and
infrastructure, it is not reasonable
to think that proprietary charging
pads and adapters are anything
more than short-term options
that will help prepare consumers
for the universal, integrated,
globally-available solution they are
expecting.
Given this understanding
of the marketplace, many
underdeveloped and divergent
thoughts have been introduced
from both the developmental and
perceived consumer points of view.
These range from broadcasting
power and charging any device,
in any position, anywhere in a
room, to leveraging near-field
solutions where devices interact
with charging hot spots built into the
surrounding infrastructure.
As the industry matures and more
specific questions and concernsaround wireless power technology
develop along with it, there is a
necessary sequence of events that
is required for mass adoption of the
technology worldwide. The first of
these is a deeper understanding
of the available technologies,
their strengths and limitations
and the importance of creating
a global standard to serve as
the most effective vehicle for theevolution of the universal wireless
power solutions that is capable of
answering the consumer demand
for a universal, integrated solution.
A simple assumption would be that
consumers want wireless power in
the same vein as Wi-Fi solutions
where power would be available
anywhere. Initially, this holds true
until the aspects of efficiency,
safety, cost and interoperabilityweigh into the equation. This then
becomes a complex consideration
of solutions. This is the underlying
reason to further discuss these
considerations, compromises and
available solutions.
THE PRIMARY
EMBODIMENTS OF
CONSUMER-READY
WIRELESS POWER
Wireless power can be transferred a
number of ways. From microwaves
and lasers, to the way Tesla did
it, to simple embodiments like
rechargeable toothbrushes--
all these methodologies have
limitations that potentially
undermine mass adoption and
commercialization. As an opening
caveat, microwave and laser-type
wireless power systems that are
typically point-to-point sources have
been excluded from this discussion.
That said, development teams are
stretching the boundaries of physics
using available components to
create systems that are able to
compete with the efficiencies of
wired solutions while offering
the conveniences of wire-free
connections. The solutions being
offered currently are based on high-
frequency broadcast, mid-range
inductive coupling or near-field
inductive coupling technologies.Other terms like magnetic
resonance may be used, but think
of this in terms of a very well-tuned
and possibly larger inductively
coupled transmitter and receiver
system that can be configured and
enabled in various ways.
Several terms are used in defining
inductive wireless power transfer,
including magnetic coupling,
where wireless power transfer
is typically near-field inductive
coupling. When discussing terms
like non-radiated energy, this would
assume magnetic coupling or, more
specifically, inductive coupling.
This can refer to both near-field and
mid-range inductive coupling. This
discussion defines these systems
as near-field and those that use a
larger primary coil for mid-range
distances as near-field, far-edge.In addition, mid-range is defined
as somewhere between one and
ten times the diameter of the
transmitting coil.
Far-field is typically radio frequency
(RF) and has a lower wavelength with
a smaller antenna and propagates
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TECHNICAL ARTICLE
effectively. This discussion also
reviews the considerations of these
systems for use and integration. As
a general term, both RF and mid-
range wireless power are defined
here as broadcast power systems,
where the range invokes additional
considerations in field, susceptibility
and coverage in both radiated and
non-radiated terms. The basic term
broadcast for discussion is in a
one-to-many relationshipthat is to
say, one transmitter coil providing
power to many receiver coils. In
these broadcast relationships, the
design requires every receiver in
the system to suffer the differencefrom the most demanding
requirement on the system. This
will typically be expressed as
losses in the transmitter and
receiver. In broadcast systems, the
consideration of the one-to-many
relationship is very interesting;
however, it brings many additional
demands on both sides of the
power system. On the receiver side,
it demands that any device has theprotection and limiting of the largest
device. This places very interesting
and challenging requirements
on the receivers to manage these
voltages and power transactions.
Although technology has advanced
in DC-to-DC conversion, the
efficiency of such systems will be
challenged. Other factors include
extraneous losses in the field and
other parasitic elements. With
close proximity systems, these
can be easily managed. Each
power channel delivers only what
is requested for peak efficiency
which, in turn, limits losses.
Another key challenge is controlling
in various modes with broadcast
power. Consider the option to run as
a battery charger, power supply or
fast rate charger. A difficult problem
for the one-to-many broadcast
power system is managing powersupply interactions, as seen in
Figure 1, along with meeting the
time-dependent requirements of a
demanding power system.
It would be reasonable to think
that for most broadcast systems
the solution is one output and one
charging solution, resulting in more
waste. It is also important to point
out that batteries are typically more
forgiving than power systems. Withcloser proximity systems, scalable
power from one transmitter over
many control modes has been more
easily demonstrated. This problem
appears to be very challenging
in broadcast power and may limit
applications and interoperability.
Figure 1: The power supply management demands of a basic 45 watt laptop power supplyfrom start up charging only, power and charging.
MID-RANGE
WIRELESS POWER
Mid-range wireless power, as
defined here, is wireless power thatextends to larger areas of influence.
Mid-range wireless power is built
around the idea of using resonant
magnetic induction or near-field,
far-edge to send power between
coils across distances from
several inches to several feet. The
limitations of this concept start
with the diameter of the transmitter.
Typically, an inductive coupled
system can transmit roughly thediameter of the transmitter. With
additional tuning of the primary and
secondary Q along with impedance
matching capacitance or inductance
to achieve a matched magnetic
resonance, these distances
can be extended. To date, the
publications and experimentation
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TECHNICAL ARTICLE
show highly tuned systems that can
transmit power over substantial
distances with transmitter and
receiver diameters that are larger
than many consumer electronic
devices. This tuning and the use
of well-engineered low-loss coils
in turn allow these distances to be
extended. It should be noted that the
discussion to date has been about
extending distance and efficiency
to ratios greater than four times the
diameter of the transmitter. This
is not to say that it will necessarily
produce high efficiency, but rather
that power can be transferred at this
distance. For many, this will be moreinteresting at shorter distances
where efficiencies are higher and
suitable distances for specific
applications are gained. This
allows gains that create exciting
opportunities but again benefit the
closer proximity applications the
most by extending distances and
maintaining the highest efficiencies.
The opportunities in this range are
exciting but require additionalconsiderations.
In reviewing the case of early RF
wireless home control technologies
that attempted to leverage the same
thinking, these systems were tested
in situations where significant gaps
in coverage and limiting factors like
aluminum siding were discovered
that created additional consumer
confusion and cost. Imagine these
power transfer coils on the insidewall of a house with aluminum
siding. This places a large coil
within six inches of a metal surface.
This is not an easy solution as the
screen that holds plaster or stucco
would present the same challenges
to an RF-based power solution.
Broadcast wireless power faces the
same probable set of challenges,
the most significant of which is
consumer education. Today, this
technology has been presented in a
way that appears to be magic while
the real comparisons will be made
by the designers of future products.
Wireless-powered devices can be
very finely tuned and operate at
specific frequencies. If a device,
printed circuit, semiconductor or
wire circuit happen to be tuned
to these frequencies, they will
suddenly develop a potential from
the power being broadcasted. This
opens up channels of interferencethat threaten efficiencies as well as
functionality, creating usage issues
for consumers. And, as distances
between power sources and
devices increase, these issues are
amplified beyond simple shielding
solutions. Additionally, wireless
power in larger areas may present
susceptibility and compatibility
issues with devices. This may
create a need for regulation and
standardization that would require
new levels of testing and design
for devices to prevent additional
reliability and warranty failures.
Potential susceptibility failures
can be immediate or latent failure
modes.
In reviewing the claims of non-
radiated energy by some, one
could see how it is more directed
as in magnetic fields, but a specificenergy is still present at the transmit
frequency within that field. This is
typically strongest between these
coils. It should be noted that this
can be minimized but a component
of radiated and non-radiated energy
will be present.
Orientation provides yet another
challenging factor for broadcast
power as distance increases. With
this, consideration must be given
to not only the physical orientation
and alignment between the
specific transmitter and receiver,
but also orientation and alignment
in conjunction with other bodies
of various materials that fall within
the broadcast field. If this condition
happens to restrict the field
completely, the consumer is left with
a dead spot. These circumstances
will change performance and
operation unless the system can
adjust and respond accordingly.
This becomes even more importantwhen considering efficiencies in
a highly tuned system. Adaptive
intelligent solutions can provide
gains in performance when facing
these issues. However, if adaptive
intelligence is not built into systems
at the outset, the system risks
potential technology failures and
reduced consumer confidence.
In addition to tuning and orientation
challenges, mid-range wireless
power solutions face coil geometry
factors that should also be
considered. The laws of physics
have proven that well-matched coils
provide the best power transfer.
Referencing a recent paper by
researchers at Koninklijke Philips
Electronics N.V., one can see the
possible practical applications
using these methods [2]. All
efficiencies referenced in thefollowing efficiencies section of this
paper also consider tightly matched
transmitter and receiver coils.
Subsequent demonstrations have
been realized with vastly different
ratios from the transmitter diameter
to receiver diameter. It should be
pointed out that these efficiencies
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TECHNICAL ARTICLE
may follow some portion of these
ratios. This may further degrade
the efficiency references provided
below for these systems as these
ratios are changed from the
mentioned efficiency. The example
that follows uses a transmitter and
receiver each with a 25cm coil, and
this system demonstrates an AC
system efficiency of 15 percent.
By changing the receiver coil
from 25cm to 25mm (a typical size
needed for a handheld device)
there should be a negative impact in
efficiency. It would also be expected
that any change in coil size would
negatively impact tuning, so thissystem would need to be highly
tuned as the system changes. Given
these variables, there is opportunity
for more system inefficiency at the
system level when considering
interoperability than has been
communicated previously.
Another consideration with mid-
range wireless power systems is
power control. When powering a
laptop, a headset and cell phone,
the power transmitted must be
tailored to the highest demand. The
other devices must be designed
to either accommodate this input
amplitude or other tradeoffs must
be made. This represents yet
another opportunity for losses,
leading to overall lower efficiency
and potentially greater thermal
dissipation in the device. This
also represents additional designconsiderations and protections
for smaller devices that already
struggle to reach their high level of
integration.
Appendix
1. AcuPOLL Research, Inc.,
August 2008 Project Alamo
River
2. Eberhard Waffenschmidt and
Toine Staring, Limitation of in-
ductive power transfer for con-
sumer applications, Submittedas synopsis to European Power
Electronics (EPE) Conference
2009, Barcelona, Spain, 8-10
September, 2009.
3. AIP Industrial Physics Forum
(November 13, 2006). Retrieved
from: http://powercastco.com/
PDF/HarvesterDataSheetv2.pdf
4. Aristeidis Karalis,
J.D.Joannopoulos, and MarinSoljacic (2006). Wireless Non-
Radiative Energy Transfer.
5. AIP Industrial Physics Forum
(November 13, 2006). Retrieved
from: http://powercastco.com/
PDF/HarvesterDataSheetv2.pdf
6. Hadley, Franklin (Version from
November 19, 2008).Retrieved
from: http://web.mit.edu/isn/
newsandeven ts /wire less_power.html
7. Eberhard Waffenschmidt and
Toine Staring, Limitation of in-
ductive power transfer for con-
sumer applications, Submitted
as synopsis to European Power
Electronics (EPE) Conference
2009, Barcelona, Spain, 8-10
September, 2009.
8. Hadley, Franklin (Version fromNovember 19, 2008). Retrieved
from: http://web.mit.edu/isn/
newsandeven ts /wire less_
power.html
9. Intel Labs (Accessed Octo-
ber 2009). Wireless Resonant
Energy Link. Retrieved from:
http://seattle.intel-research.net/
research.php#wrel
10. Eberhard Waffenschmidt and
Toine Staring, Limitation of in-
ductive power transfer for con-sumer applications, Submitted
as synopsis to European Power
Electronics (EPE) Conference
2009, Barcelona, Spain, 8-10
September, 2009.
11. http://www.ecoupled.com
12. Eberhard Waffenschmidt and
Toine Staring, Limitation of in-
ductive power transfer for con-
sumer applications, Submittedas synopsis to European Power
Electronics (EPE) Conference
2009, Barcelona, Spain, 8-10
September, 2009.
13. http://www.wirelesspowercon-
sortium.com
14. Aristeidis Karalis,
J.D.Joannopoulos, and Marin
Soljacic (2006). Wireless Non-
Radiative Energy Transfer.
About the Authors
DAVID W BAARMAN
David Baarman is the Director of
Advanced Technologies at Fulton
Innovation and the lead inventor
of eCoupled intelligent wireless
power technology. Mr. Baarman
is responsible for the technical
supervision and development ofeCoupled technology and other
Fulton Innovation technologies. Mr.
Baarman joined Amway in 1997,
where he first pioneered the use of
intelligent inductive coupling in the
eSpring Water Purifier. With over
20 years of leadership experience in
the development of consumer and
http://powercastco.com/PDF/HarvesterDataSheetv2.pdfhttp://powercastco.com/PDF/HarvesterDataSheetv2.pdfhttp://powercastco.com/PDF/HarvesterDataSheetv2.pdfhttp://powercastco.com/PDF/HarvesterDataSheetv2.pdfhttp://web.mit.edu/isn/newsandevents/wireless_power.htmlhttp://web.mit.edu/isn/newsandevents/wireless_power.htmlhttp://web.mit.edu/isn/newsandevents/wireless_power.htmlhttp://web.mit.edu/isn/newsandevents/wireless_power.htmlhttp://web.mit.edu/isn/newsandevents/wireless_power.htmlhttp://web.mit.edu/isn/newsandevents/wireless_power.htmlhttp://seattle.intel-research.net/research.php#wrelhttp://seattle.intel-research.net/research.php#wrelhttp://www.ecoupled.com/http://www.wirelesspowerconsortium.com/http://www.wirelesspowerconsortium.com/http://www.wirelesspowerconsortium.com/http://www.wirelesspowerconsortium.com/http://www.ecoupled.com/http://seattle.intel-research.net/research.php#wrelhttp://seattle.intel-research.net/research.php#wrelhttp://web.mit.edu/isn/newsandevents/wireless_power.htmlhttp://web.mit.edu/isn/newsandevents/wireless_power.htmlhttp://web.mit.edu/isn/newsandevents/wireless_power.htmlhttp://web.mit.edu/isn/newsandevents/wireless_power.htmlhttp://web.mit.edu/isn/newsandevents/wireless_power.htmlhttp://web.mit.edu/isn/newsandevents/wireless_power.htmlhttp://powercastco.com/PDF/HarvesterDataSheetv2.pdfhttp://powercastco.com/PDF/HarvesterDataSheetv2.pdfhttp://powercastco.com/PDF/HarvesterDataSheetv2.pdfhttp://powercastco.com/PDF/HarvesterDataSheetv2.pdf -
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TECHNICAL ARTICLE
industrial products, Mr. Baarman
took the technology behind eSpring
and developed it to power everyday
technologies, including consumer
electronics, with a diverse range
of power needs. Mr. Baarmans
efforts have led to national and
global recognition of eCoupled
technology and the acquisition of
former competitor, Splashpower, in
May 2008. Mr. Baarman has more
than 700 U.S. and foreign patents
that are granted or pending.
JOSHUA SCHWANNECKE
Joshua Schwannecke is a Research
Scientist with the Advanced
Technologies Group at Fulton
Innovation. Josh has more than fiveyears of experience with wireless
power and developing solutions
using eCoupled technology. He has
developed wireless power solutions
for the Amway eSpring Water
Purifier and other devices including
hearing aids, phones, headsets,
laptops, and power tools. He also
works closely with Fultons partner
companies to research wireless
power solutions for prototype
products. Mr. Schwannecke holds
a Masters in Electrical Engineering
from Michigan State University and
has received an excellence award
for coil design and optimization. He
holds one granted patent and has
eight published patent applications.
http://bit.ly/nKLRXohttp://bit.ly/nKLRXohttp://bit.ly/nKLRXohttp://bit.ly/nKLRXohttp://bit.ly/nKLRXohttp://bit.ly/nKLRXohttp://bit.ly/nKLRXo -
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60V Fault Protected, 3.3V to 5V, 20V Common Mode
Range, RS-485/RS-422 Transceivers with Cable Invert
and 15kV ESD
ISL32450E, ISL32452E, ISL32453E, ISL32455E, ISL32457EThe ISL32450E through ISL32457E are 3.3V to 5V powered, fault
protected, extended common mode range differential transceivers
for balanced communication. The RS-485 bus pins (driver outputs
and receiver inputs) are protected against overvoltages up to
60V, and against 15kV ESD strikes. These transceivers operate
in environments with common mode voltages up to 20V
(exceeds the RS-485 requirement), making this RS-485 family
one of the more robust on the market.
Transmitters are RS-485 compliant with VCC 4.5V and deliver a
1.1V differential output voltage into the RS-485 specified 54
load even with VCC = 3V.
Receiver (Rx) inputs feature a Full Fail-Safe design, which
ensures a logic-high Rx output if Rx inputs are floating, shorted, or
on a terminated but undriven (idle) bus. Rx full fail-safe operation
is maintained even when the Rx input polarity is switched (cable
invert function on ISL32457E).
The ISL32457E includes a cable invert function that reverses the
polarity of the Rx and Tx bus pins in case the cable is
misconnected during installation.
See Table 1 on page 2 for key features and configurations by
device number.
Related Literature
See FN7784, ISL32470E, ISL32472E, ISL32475E,ISL32478E: Fault Protected, Extended Common Mode Range,
RS-485/RS-422 Transceivers with 16.5kV ESD
Features Fault Protected RS-485 Bus Pins. . . . . . . . . . . . . Up to 60V
Extended Common Mode Range . . . . . . . . . . . . . . . . . . 20V
Larger Than Required for RS-485
15kV HBM ESD Protection on RS-485 Bus Pins
Wide Supply Range . . . . . . . . . . . . . . . . . . . . . . . . . 3V to 5.5V
Cable Invert Pin (ISL32457E Only)
Corrects for Reversed Cable Connections While Maintaining Rx
Full Fail-safe Functionality
1/4 Unit Load for Up to 128 Devices on the Bus
High Transient Overvoltage Tolerance. . . . . . . . . . . . . . 80V
Full Fail-safe (Open, Short, Terminated) RS-485 Receivers
Choice of RS-485 Data Rates . . . . . . . . . . . . 250kbps or 1Mbps
Low Quiescent Supply Current . . . . . . . . . . . . . . . . . . . 2.1mA
Ultra Low Shutdown Supply Current . . . . . . . . . . . . . . . 10A
Pb-Free (RoHS Compliant)
Applications Utility Meters/Automated Meter Reading Systems
Air Conditioning Systems
Security Camera Networks
Building Lighting and Environmental Control Systems
Industrial/Process Control Networks
FIGURE 1. EXCEPTIONAL ISL32453E RX OPERATES AT >1Mbps
EVEN WITH 20V COMMON MODE VOLTAGE
FIGURE 2. TRANSCEIVERS DELIVER SUPERIOR COMMON MODE
RANGE vs STANDARD RS-485 DEVICES
TIME (200ns/ DIV)
VO
LTAGE(V)
0
5
10
15
20
B
A
RO
VCC = 3V
VID = 1V2Mbps
ISL3245XE
COMMO
N
MODERANGE(V)
STANDARD RS-485TRANSCEIVER
-20
-7
0
12
20
February 20, 2012
FN7921.0
Intersil (and design) is a registered trademark of Intersil Americas Inc. Copyright Intersil Americas Inc. 2012
All Rights Reserved. All other trademarks mentioned are the property of their respective owners.
Get the Datasheet and Order Samples
http://www.intersil.com
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Combining the operation of a boost regulator and a
negative voltage converter can generate a negative
supply from a single low-voltage supply. The circuitin Figure 5 shows a standard application circuit for a
+20V supply along with two op amps, two diodes and
two capacitors to generate the 20V supply. This article
will discuss the basic operation of a boost converter to
generate a larger positive supply voltage. Equations
are derived to determine the minimum inductor value to
maintain a safe peak inductor current, and a maximum
inductor value to maintain continuous conduction mode
(CCM) operation. The article will then discuss the
generation of a negative supply and the restrictions of
the design.
Understanding the Boost Topology:
Before we add the additional circuitry to generate the
negative supply, it is important to understand how the
boost convertor produces an output voltage that is
always greater than the input voltage. In order to do this,
we analyze the boost circuits in Figure 1 and the current
waveforms in Figure 2. For this analysis, we account
for all the losses in the charging and discharging loops
in our equations. This should help to give a complete
understanding of the circuit.
However, the output voltage is not dependent upon any
losses in the circuit. This is because all the losses are
inside the circuits feedback loop of the ISL97701which
we will use as an example hereand are automatically
accounted for. The output voltage is defined from
the feedback resistor network shown in Figure 5 and
calculated in Equation 1, where VrefFB is the internal
reference voltage of the ISL97701.
( )
.( )
( )
V V
R
R R
V VR
R R1 15 1
OUT refFB
OUT
2
1 2
2
1 2
:
:
=+
=+
Positive Supply:
Figure 6a shows the basic boost converter circuit.
During one switching cycle, the transistor Q1 turns on
and turns off. During the time Q1 is on, the inductor
L1 is placed in series with the VIN supply through the
Don LaFontaineSenior Application Engineer
A Simple Circuit to GeneratePlus and Minus Supplies
Using a Boost Regulator
+++
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TECHNICAL ARTICLE
ISL97701s integrated boost FET (Q1). The diode D1 is
reverse biased and the circuit reduces to that shown in
Figure 6b. The voltage across the boost inductor (L1)
is equal to VIN (VDS + IL1 x RL1) and the current
ramps up linearly in inductor L1 to a peak value at time
DT. Thepeak inductorcurrent (IL1) is calculated in
Equation 3 and shown graphically in Figure 6b. Any
load requirements during this phase are supplied by the
output capacitor C1.
The duty cycle (D) in Equation 5 is determined by setting
the losses in Equation 5 (IL1 x RL1, VD1, VDS) to zero
because they are within the feedback loop of the ISL97701.
The ISL97701 varies the duty cycle continuously to keep
Figure 1
V Ldtdi
iLV
dt ( )2LL
LpkL
T
DT
0
= = #
When Q1 turns off, because the current in an inductor
cannot change instantaneously, the voltage in L1 reverses
and the circuit becomes that shown in Figure 1c. Now the
no-dot end of L1 is positive with respect to the dot end
and D1 becomes forward biased. Because the dot end is
at VIN, L1 delivers its stored energy to C1 and charges it
up to a higher voltage than VIN. This energy supplies the
load current and replenishes the charge drained away
from C1. During this time, energy is also supplied to the
load from VIN. The voltage applied to the dot end of the
inductor is (VIN IL1 x RL1), while the voltage applied
to the no-dot end of L1 is now the output voltage (VO)
plus the diode forward voltage (VD). The voltage across
the inductor during the off-state is ((VO + VD1 + IL1 x
RL1) VIN). The inductor current during the off-time of
the switch (T-DT) is calculated in Equation 4 and shown
graphically in Figure 1c.
IL
V (V I R )DT ( )3L1(on)
IN DS L1 L1=
- + ##D
IL
(V V I R ) V(T DT) ( )4L1(off)
o D1 L1 L1 IN=
+ + --
##D
In steady-state conditions, the current increases during
the on-time of the switch and decreases during the off-time of the switch (Figure 7). Both on-time and off-time
currents are equal to prevent the inductor core from
saturating. Setting both currents equal to each other
and solving for VO results in the continuous conduction
mode boost voltage shown in Equation 5.
V1 D
V I R )V V
1 DD
( )5oin L L
D1 DS= -
-- -
-
##
Figure 2
RL1
IL1
RL
L1 D1
Q1C1
IO
VIN
VDS
+
VO
RL1
IL1
IQ1
L1
(VO+VD+IL1xRL)VIN(T-DT)
L
Q1VIN+
RL1
IL1
RL
L1 D1
DT
DTOT
T
VO
C1
VIN+
IO
a
b
a
b
IL1(of f) =
(VIN(VDS+IL1xRL1))DT
L
IL1(on) =
DTOT
IL1
IL1
IL1(pk)
IL1(a ve)
ID1
IQ1
OT DT T
OT DT T
OT DT T
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TECHNICAL ARTICLE
VO constant, regardless of the conduction losses as
a function of load current. With the losses set to zero,
Equation 5 reduces to Equation 6. This results in the
value for the duty cycle shown in Equation 7.
the output current multiplied by the gain of the boost
regulator as shown in Equation 10.
VV
1 D1 ( )6
IN
O=
-
D 1V
V( )7
O
IN= -
Inductor Selection
The inductor selection determines the output ripple
voltage, transient response, output current capability
and efficiency. Its selection depends on the input
voltage, peak inductor current, output voltage, switching
frequency and maximum output current. When choosing
an inductor, make sure the saturation current of theinductor is greater than the IPEAK of the circuit. Likewise,
the transistor should be able to handle peak current
greater than IPEAK. The peak inductor current is shown
in Figure 10 and can be calculated using Equation 11.
Figure 3
From Figure 3, we can see that the peak inductor current
IL1 is equal to the average inductor current IL1 plus one
halftheIL1current,asshowninEquation8.
I I21
I ( )8L1(PEAK) L1(AVE) L1(ON)= + D
The average power IN is equal to the average power
OUT divided by the efficiency of the circuit, as shown inEquation 9.
V IEff
V I( )9IN L1 (AVE)
O O=##
Where Eff is equal to the efficiency of the ISL97701 boost
regulator.
Therefore, the average inductor current is equal to
IV Eff
V I( )10L1(AVE)
IN
O O=#
#
IL1wasdefinedinEquation3andthedutycycle(D)
in Equation 7. Substituting Equation 7 into Equation
3 and adding it to Equation 10 results in Equation 11.
Equation 11 gives the inductors peak current in terms of
input voltage, output voltage, switching frequency, and
maximum output current (again, the losses due to VDS
and IL1 x RL1 are not included because they are inside
the feedback loop of the ISL97701).
IV Eff
V I1/2
L V FREQ
V (V V )( )11L(PEAK)
IN
O O
O
IN O I N+
-
=#
#
#
# #
#
By rearranging the terms in Equation 11, we can solve
for the inductor value using Equation 12.
L(I V Eff I V )2V FREQ
V Eff (V V )( )12
PK IN O O O
IN2
O IN
-
-
=
Equation 12 is useful for determining the minimum
value of L that the circuit can handle without exceeding
the peak current through the inductor, and therefore the
switch Q1. The maximum peak current (IPEAK) allowed
through Q1 for safe operation is given in the electricaltable as 1.2A.
Minimum Inductor Value Design Example
Given: VIN = 5V, VO = 20V, IO = 50mA, IPK = 1.2A, freq
= 1MHz, Eff = 0.85 (Efficiency of 85% from Figure 3 in
the ISL97701 data sheet).
Equation 12 gives us the boundary condition for the
smallest inductor we can have to ensure the peak
current through Q1 is less than the max limit of 1.2A.
The minimum inductor value for the given conditions isdetermined to be 1.94H.
1.94 H ( )13= n
L(1.2A (5)(0.85) 50mA(20)) 2 (20) 1MHz
(5V) (0.85)(20 5)2
-
-
=
Maintaining CCM Design Example
For maximum efficiency, the boost converter needs to
IL1
IL1
IL1(pk)
IL1(a ve)
O DT T
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TECHNICAL ARTICLE
Negative Supply
The operation of the negative supply is best understood
by considering Figure 5. We will start our analysis
under steady state conditions (the inductor operating
in continuous conduction mode and C1 is equal to thevoltage calculated in Equation 1).
When Q1 turns off, the inductor voltage flies up turning
on D1 and D3. Diode D2 is blocking current flow from
C3. The inductor current now charges both capacitors
C1 and C2 with the polarity shown in Figure 5. The
voltage on C2 is equal to the voltage on C1 plus the
forward voltage drop of D1.
When Q1 turns on, Diodes D1 and D3 are blocking and
capacitor C2 is now in parallel with capacitor C3 through
D2 (which is now on), as seen in Figure 4. This connectionresults in a negative voltage being transferred on to C3.
The voltage transferred to C3 is equal to the voltage on
C1 as shown in Figure 4 and Equation 18.
be operated in continuous conduction mode (CCM). To
maintain continuous conduction mode operation of the
boost regulator, the value of IL1 needs to be greater than
orequaltoIL1/2(Figure3).
I21 I
V Eff
V I1/2
L V FREQ
V (V V( )14
L1(AVE) L1
IN
O O
O
IN O IN)-
#
#
#
# #
#
$
$
D
Rearranging terms and solving for L results in Equation
15.
L 1/2
V Eff
V IV FREQ
V (V V )(15)
IN
O OO
IN O IN-
#
#
#
# #
#
$
To maintain continuous conduction mode operation for
the given circuit design conditions above, the value of L
has to be greater than 7.96H.
L 1/2
5V (0.85)
20V 50mA20 1MHz
5V (20V 5V)-#
#
#
# #
#
$
7.96 H ( )16$ n
It should be noted that when there is a light load, the circuit
can slip into discontinuous conduction mode, where the
inductor becomes fully discharged of its current each
cycle. This operation will reduce the overall efficiency
of the supply. Using Equation 15 and making the value
of the inductor large enough for a given minimum
output current will ensure continuous conduction mode
operation.
Output Capacitor
Low ESR capacitors should be used to minimize the
output voltage ripple. Multilayer ceramic capacitors
(X5R and X7R) are preferred for the output capacitors
because of their lower ESR and small packages.Tantalum capacitors with higher ESR can also be used.
The output ripple can be calculated in Equation 17:
Vf C
I DI ESR ( )17O
SW 1
OUT
OUT=#
#
#D +
For noise sensitive applications, a 0.1F placed in
parallel with the larger output capacitor is recommended
to reduce the switching noise.
Figure 4
The efficiency of the charge transfer between the
two capacitors is related to the energy lost during this
process. Energy is lost only in the transfer of charge
between capacitors if a change in voltage occurs. Theenergy lost is defined in Equation 19:
(V D ) D V 0
V V
( )18C1 1 2 C3
C1 C3
+ - - =
=
E21
C (V V ) ( )192 12
2
2-=
Where V1 and V2 are the voltages on C2 during the
charging and transfer cycles. If the impedances of
C2 and C3 are relatively high at the 1MHz frequency
compared to the value of RL, there will be substantial
+
+
+
C2
V = VC1 +D1
Q1 turns on connecting
C2 to ground as shown
VC3
C3
C1
D1
D2
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TECHNICAL ARTICLE
difference in the voltages V1 and V2. Therefore it is
not only desirable to make C3 as large as possible to
eliminate output voltage ripple, but also to employ a
correspondingly large value for C2 in order to achieve
maximum operation efficiency.
Output Voltage Regulation Using Op Amps
The final output voltage regulation is accomplished
using the ISL28208 Dual Opamp. The voltage developed
by the boost converter powers the amplifiers and the
output voltage is calculated using Equations 20 and 21.
currents between 25mA and 125mA. The circuit will
work perfectly fine outside these ranges, as long as the
maximum IPEAK current is not exceeded (Equation 12).
The only drawback will be a reduction in the efficiency
of the circuit. The percent efficiency could drop fromthe 80s to the 60s as the operation goes from continuous
conduction mode to discontinuous conduction mode.
Reference the ISL97701 data sheet for additional
information on performance.
About the Author
Don LaFontaine is a Sr. Principal Application Engineer/
Sr. Engineering Manager with Intersils Analog/Mixed
Signal product line in Palm Bay, Florida. His focus is on
precision analog products. He has been with Intersil
Corp. for the last 30 years. He graduated from theUniversity of South Florida with a BSEE in 1985.
V 5V (R R ) /R ( )20OUT(positive) 3 4 3:= +
V V R /R ( )21OUT (negative) OUT (positive) 6 5= :-
Restriction On DesignFor reasonable voltage regulation of the negative supply
voltage, the negative supply current needs to be less than
or equal to the positive supply current. This is because
the control loop for output voltage regulation is around
the positive supply voltage only.
I I ( )22OUT(positive) OUT(negative)$
The ISL97701 is optimized to work best for a small
range of inductors. The slope compensation ramp
generator, inside the ISL97701, is optimized for inductorvalues between the range of 4.7H to 15H and output
Figure 5
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C2
C3
C1
C0
VOUT(positive)
VOUT
FB
ISL97701
ISL28108
ISL28108
VDDOUT
VDD
NEN
NSYNC
GND
LX20V
VOUT(negative)
- 20V
4.7F6.8H
4.7F
4.7F
R1383k
R2
R3
22.2k
33.2k
R4
100k
R5
100k
R6
100k
5F
- 20.99V
5V
5V
V+
V
V+
V
5V
20.99V
L1
Q1
D2
D1 V0
D3
+
+
+
+
+
O
SCILLATOR
AN
DCONTROL
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