EEWeb Pulse - Volume 104 by EEWeb Magazines

Hartley Peavey CEO & Founder of Peavey

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CONTENTS

PULSE

Hartley Peavey

PEAVEY ELECTRONICS

A conversation about how this leading amplifier company succeeded by building quality gear at an affordable price.

Featured Products

This week’s latest products from EEWeb.

Spansion Acquires Fujitsu’s Analog Business

How this acquisition will strengthen Spansion’s existing Flash and memory solutions.

Architecture Choices for Graphics Applications

4 14

How lower-end graphics display controllers (GDCs) offer surprising performance without inflating the bill of materials.

Flexible Display Technologies

OLED screens promise to increase durability to extend the lifetime of phones, laptops, tablets, and other mobile devices.

RTZ

Return to Zero Comic

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PULSE

Hartley Peave 1950s to early to B.B. King to play the g he had to t at his pare music price. Aft ampl

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INTERVIEW

ey is the CEO and Founder of Peavey Electronics. Growing up in Meridian, Mississippi in the mid y 1960s, Peavey was exposed first hand to the early origins of rock & roll music--from early Elvis g to Muddy Waters. Like many teenagers his age, the rise of rock & roll inspired Peavey to learn guitar. However, after being kicked out of three different bands for being a “lousy guitar player,” turn to something he knew he could actually do: build electronics. Peavey spent countless hours ents dining room table building guitar pick-ups and amplifiers, which got the attention from his cian friends. In 1965, he founded Peavey electronics to build quality equipment for an affordable ter being told by family and friends that he could never compete with the competition, Peavey’s lifier business grew and grew to become one of the leading amplifier companies in the industry.

e spoke with Hartley Peavey about what differentiates his products from his competitor’s, some the new technologies he’s developing, and the unique work culture in the company’s Meridian, Mississippi headquarters.

“I guess I’m just an old rebel, but the best way to get me to do something is to tell me I can’t do it.”

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PULSE

“ By definition, you cannot be the best without being different. I was different—I approached things from a totally different standpoint.”

Did your interest in blues and rock & roll prompt you to build your first amplifier? When I decided that I wanted to get into the business, I had already been kicked out of 3 bands. When I was in high school, I took every shop course I could possibly take— machine shop, sheet metal shop, basic electricity, advanced electricity, and what we then called Radio. I could solder, I could run a milling machine, I could build a guitar bridge or tremolo. Give me a piece of brass or aluminum and in about an hour and a half—you got it. I thought everybody could do it, but it turns out, I was a much better builder of gear than I was a player. After I got kicked out of the third band, I did a very difficult thing; I had to look in the mirror and be totally honest with myself. Essentially I told myself that it looked like I wasn’t going to be a rock star and because I was really good at building things, I came up with an idea: to build good gear at a fair price. Rock & roll started in the 1950s and it exploded; there was Elvis, Bo Diddley, Chuck Berry, and Ray Charles and all those people. It was a tremendous thing and I was there to witness it. I bought records for my dad’s record shop. As he put it, I knew what kind of music that kids wanted. By the early 1960s, this rock & roll music that had inspired everybody “turned corporate”—the lawyers had taken over the music business, and big conglomerates got involved. Meanwhile, the British were very influenced by this American rock & roll and

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they kind of repackaged it and sold it back to us in the form of the Rolling Stones and the Beatles and what we refer to as the British Invasion started around 1962 and 1963. From the early to mid 1960s through most of the 70s were the glory years of conglomerates—this is when CBS bought Fender, and all these companies with diverse interests began buying out music and sound companies. It was a very interesting time because what happened was that the quality of their products went down and the prices, in some cases, even doubled—all within a few years. This exacerbated the feeling amongst musicians that they wished somebody would make good gear at fair prices. There were amps being sold back then that would go for upwards of $1500—this is when gasoline was selling for 32 cents a gallon. If you want to know what that cheesy transistor 100-watt amplifier would cost today, simply multiply it by 10 ($15,000). I felt like I could easily compete with those people, but I was too stupid to know that what I was attempting was impossible. I call that the “Bumblebee Effect.” If you know anything about bees, you’d know that the bumblebee is aerodynamically incapable of lifting its own body weight. Unfortunately, nobody told the bee that so it flies anyway. I didn’t know that what I was attempting was impossible, so I started out with the crazy idea that I could be the best. By definition, you cannot be the best without being different. I was different—I approached things from a totally different standpoint.

INTERVIEW The music instrument manufacturers were not very progressive and most of them weren’t even using soldering machines—everything was being hand-done and I decided that my first amplifier should be a solid-state amplifier because all the amps I had built up till then, were tube types. I went into the business as Peavey in 1965 after I graduated from Mississippi State University. I started this company with the simple goal of being the best. Everything I did, from then till now, has been different. Many of my competitors spend most of their time trying to recreate the “glories of the past.” Peavey, over the course of our 48 years, has accumulated over 180 patents, which is probably more than all of our competitors put together.

How has amplifier innovation changed over the years? Sadly, a lot of what people in the guitar and amp business do is just copy old designs as if those old designs were optimal. Certainly there were some interesting designs, but not optimal. It’s rather educational to read some of the early amp catalogues, because back in the mid 1950’s the design goal of amplifier designers was to minimize distortion, which was a main selling point. Most of the amplifiers that are thought to sound good, interestingly enough, were not designed by engineers— they were designed by technicians who didn’t understand gain structure. A lot of the amplifiers that were designed by these techs distorted, which today, is what most guitar players seek. It’s an interesting dichotomy from an engineering standpoint because the “bones of companies” that have set out to design a “proper” guitar amplifier are all over the place. When you design a “proper” guitar amp, what you really have is hi-fi amp. If you want a lesson in how bad your guitar can sound, plug it into a hi-fi amp. That’s been quite a revelation to a lot of people.

have to be what I want. The goal of Peavey is for the musicians to tell us what they want, and then we’ll build it. If you are a blues player, I have a great amp for you—it has EL84 tubes and it blows every other blues amp away. But it’s not something that a heavy metal guy would want to plug in to. That’s like saying that one automobile is good for everybody. Instead of making a million versions of the same guitar, we try to do something totally different. Back in the 1970s, I decided to get into the guitar business, and decided to take a different approach from the other main guitar companies. I knew that the way they were doing it with 1890s technology was inefficient. I looked at certain well-made rifles as inspiration for the guitar neck process and found a German company with a machine for making rifle stocks. This could turn out 4 necks in five minutes. To my knowledge, nobody had ever done that before. I was the first one to introduce computer numerical control (CNC) machinery into making guitars and everyone said it couldn’t be done, but we did it. Today, everyone does it that way, but we did it nearly 40 years ago.

What are some of Peavey’s new amplifier innovations? I mentioned earlier that a lot of our competitors are trying to recreate their past glories, but we are looking toward the future. We are making investments in innovative technology across the board—with speakers, with guitar amps, with digital audio systems of all kinds. What we are able to do through the miracles of digital signal processing we could only dream about a couple of years ago. We have a software ampmodeling program that is very unique called ReValver®.

What are the key differentials between Peavey and its competitors? Constant innovation. Some of our competitors have been very successful and they have developed what they call a “signature sound.” Peavey doesn’t have a “signature sound.” All of our amps sound different because they are made for certain genres of music or certain artists. To me, if my customer is satisfied, then I’m happy. The sound of our amps doesn’t

ReValver® Software

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PULSE

Vypyr2® Modeling Amps

We got involved with this because we deal a lot with what most folks call “tone.” The fact is, no matter how good your vocabulary is, you cannot describe a tone to me and I cannot describe a tone to you. If I tell you I want a real “full bottom-end” and a “punchy mid-range” and a “nice crisp high”—what does that even mean? That’s been a real stumbling block for my competitors and me. In response to that, we created a system that allows the musician to actually design their own amplifier without knowing anything about soldering or high voltages or tubes. You can literally design your own virtual amplifier with this software. You can change the tube types, you can change the coupling capacitors, you can change the plate-load resistors, you can change the cathode resistors, tone-stacks, configuration, tube types, and the list goes on. There are over 200 well-respected speaker emulations in there. In the new version, you can output a schematic and either build it yourself, or you can download it to our custom shop and we will build you the actual amplifier from the schematic you designed with our ReValver® software. This is what I meant by saying that Peavey always does things differently. We released our latest generation Vypyr2® amps at the NAMM show in January. Amazingly, this amplifier can model other instruments. Bass Player Magazine is for bass players, but for the first time in history, they awarded our Vypyr2® modeling amp “Best Bass Amp” in the show— and it’s a Guitar amp! We can make our amp mimic almost anything. We can make an electric guitar sound very much like an acoustic guitar and vice versa. We can make an electric guitar sound like a

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bass. Our Vypyrs are unique in that they have multiple capabilities. This amp can model the other amplifiers, full effects (stomp-boxes), as well as model other instruments.

Could you tell us about Peavey’s sound reinforcement products? After years of being in the amp business, I wanted to get into high-level sound reinforcement, but I discovered that there were no speakers that would take enough power. Back then, a 50 or 60-watt amp was a big amp, and using conventional materials at the time, speakers could barely handle it. However, when you got 100 watts, 200 watts, or 300 watts, people were driving the power amplifiers into clipping and the speakers would burn up. I went to all the premium speaker makers and they told me that my “customers didn’t understand how to use their precision transducers.” I told them that when I put their “precision transducers” in a Peavey cabinet and it blows, they don’t blame you, they blame me. In desperation, we started making our own loudspeakers 1976, and we

INTERVIEW still do. To the best of my knowledge, we’re the only amp company that does that. We’ve been able to create some incredible sound systems because of that. We’ve been able to work with some outstanding artists where doing the electronics wasn’t terribly difficult, but getting the sound they wanted from new speakers to match speakers that were 30 years old was quite a trick. Uniquely, we can do it and our competitors can’t because they are limited to buying speakers “off the shelf.” Back in the 1970’s we got into the sound reinforcement business and literally revolutionized that whole marketplace. Today, if you have a coliseum, a theme park, or some big facility like an airport, you usually have a digital network and control system that sends the messages to the appropriate speakers and control signage. Peavey introduced a product in 1993 called MediaMatrix®. This was the world’s first digital audio and control network system and we have those installed all over the world. Most theme parks have a sound system that is controlled by MediaMatrix®. The sound system in the U.S. Senate, House of Representatives is MediaMatrix®. Two years ago, at the new airport in Beijing, we installed a MediaMatrix® sound system for the Olympics and we’ve done hundreds of airports, coliseums and cruise ships—we have 10,000 of these installations all over the world. Nobody ever expected a company like Peavey to come out with a very sophisticated product like that, but again, we did it first.

Is Peavey a highly vertically integrated company? Absolutely. That came about because we started in a little town in Mississippi. If I were living in L.A. or Chicago or New York, and I needed a chassis made, I’d go across town to a sheet metal place and they could make me one. Here in Mississippi, if I want a chassis, you make it yourself. I got involved in doing the metal work and silk-screening and making my own circuit boards. Long story short, Peavey is a very vertically integrated company because it is a family owned company and I own the stock. Peavey has never declared a dividend. A lot of people, unfortunately, think that the more you pay, the more you get. That’s simply not true in many cases. To assume that you can judge the quality and reliability of a product by price alone begs the question, “Are all manufacturers just alike?”

“As the company grew, it needed to provide the support structure and framework for a lot of other people so that they can do their thing. To me, Peavey is a bunch of people growing together. We don’t just make things at Peavey, we make people.”

Every manufacturer is set up differently! Their corporate structures are different, their sales methods are different, the way that they come up with their merchandise is different—you can’t unilaterally “paint everybody with the same brush.” By being vertically integrated and by not having huge bank loans, Peavey is in a very unique position to supply to the market excellent products at a fair price.

What is the work culture like at the Peavey headquarters? You will not see a coat and tie at Peavey. Everybody here is treated the same—I won’t let anybody here call me “Mr. Peavey.” Everybody is on a first-name basis. As a matter of fact, we have hundreds of telephones at the company, and our telephone directory is listed by first name only, so if you don’t know somebody’s first name, you won’t be able to find them in the directory. I treat everybody like I want to be treated. Let me give you another analogy. This is a little country town. When I decided to make amplifiers back in the mid-60s, I wanted to “do my own thing.” In order to do my own thing, I needed a support structure, so I created one never realizing that I created it for myself only. As the company grew, it needed to provide the support structure and framework for a lot of other people so that they can do their thing. To me, Peavey is a bunch of people growing together. We don’t just make things at Peavey, we make people. ■

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PULSE Demo Board for Configurable Logic Device The 74AUP1T97 provides low-power, low-voltage configurable logic gate functions. The output state is determined by eight patterns of a three-bit input. The user can choose the logic functions MUX, AND, OR, NAND, NOR, inverter, or buffer. All inputs can be connected to VCC or GND. The device ensures a very low static and dynamic power consumption across the entire VCC range from 2.3 to 3.6 V...Read More

USB 2.0 Hub Controller Chip Renesas Electronics Corporation announced the development of the µPD720115 USB 2.0 hub controller chip, which supports simultaneous USB communication and charging of portable devices such as smartphones and tablet PCs via a single USB connector. The most important feature of the µPD720115 is its implementation of USB ports with battery charging functionality which supports the USB Battery Charging Specification, Revision 1.2 (USB BC 1.2). It can help shorten system architecture development cycles and reduce development costs...Read More

14-bit Multiturn Absolute Encoder Module The AEAT-84AD provides all functions as an optoelectronicmechanical unit in order to implement, with single turn absolute encoder, an absolute multi-turn encoder with a combined capacity of up to 30 bits at extended temperature. The unit consists of an IR-LED circuit board, a phototransistor (PT) circuit board, and 6 or 7 gear wheels arranged in between the PCBs. The device also includes optical and absolute multiturn assembly with a maximum diameter of 55mm...Read More

Digital Controller with 64kB Memory The UCD3138064 is a digital power supply controller from Texas Instruments offering superior levels of integration and performance in a single chip solution. The UCD3138064, in comparison to Texas Instruments UCD3138 digital power controller, offers 64 kB of program Flash memory (vs 32 kB in UCD3138) and additional options for communication such as SPI and a second I2C port. It also creates the unique opportunity for the processor to load a new program and subsequently execute that program without interrupting power delivery...Read More

MCU with Fast Wipe Technology DeepCover® embedded security solutions cloak sensitive data under multiple layers of advanced physical security to provide the most secure key storage possible. The DeepCover Secure Microcontroller (MAXQ1852) is a low-power, 32-bit RISC device designed for electronic commerce, banking, and data security systems. It combines high-performance, single-cycle processing, sophisticated tamper-detection technology, and advanced cryptographic hardware to provide industry-leading data security and secret key protection...Read More

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FEATURED ARTICLE

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To read the Pulse interview with John Kispert, CEO of Spansion, click the image below:

Tehrani is confident that because of Spansionâ&#x20AC;&#x2122;s history with Fujitsu, and its expertise in Flash memory, not only will the acquisition go smoothly and leave the two sides feeling comfortable with each other, but that it will enable new and differentiated solutions to be offered to customers. â&#x2013;

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PULSE

Architecture Choices Balance Cost and Performance for Embedded Graphics Applications Waqar Saleem Fujitsu Semiconductor America

rom 3D rendering to image warping, the capabilities of todayâ&#x20AC;&#x2122;s graphics display controllers are integral to a broad range of innovative applications. High-end GDCs help define a productâ&#x20AC;&#x2122;s style and value with dynamic graphics that dazzle consumers. At the other end of the spectrum, modest GDCs display information clearly and simply, giving users what they want efficiently and cost effectively.

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TECH ARTICLE

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PULSE CPU

CPU Flash

CPU

VRAM+ CPU RAM

GDC

Peripherals

VRAM GDC

Peripherals

True Single Chip SOC for Basic Level Implementation

Multi-chip Solutuion for high level implementation

CPU Flash

CPU

Peripherals

GDC

VRAM+ CPU RAM

Hybrid approach to balance cost and performance

SELECTION OF BASIC GDC OPTIONS

hether simply functional or absolutely dazzling, graphics deserve careful attention and High-Quality Rubyhighly visible ways. reward good design MB86298 in There are basicCarmine QVGA display ICs, with pre-rendered Display/UXGA graphics thatMB86297 may include video input. The highEmerald-L est level provides SXGA or higher display resolution Jade Family Middle-Quality with dynamic 3D graphics andMB86R0x multiple inputs. In the middle are GDCs with WVGA display (primarily 2D Display/WVGA Coral-Q, -B, -PA dynamic graphics with some 3D also possible) and video inputs. Indigo MB88F332 Meter & Display/QVGA Lime, Mint, Scarlet Sapphire Some applications are highly cost sensitive, such as MB91590 the automotive industry, where one of the top priorities a minimized bill of materials. In basic to mid-level applications, designers can address this need by using system-on-a-chip graphics controllers as a single-chip solution. These GDCs can communicate with other automobile systems via the CAN bus and can go into shutdown power mode to preserve battery power. OpenGL ES2.0 Open VG 1.0 SGX,IRIS

OpenGL 1.1 PCI, Dual Video In and OutS

OpenGL ES2.0 Open VG 1.0 SGX,IRIS + CortexA9

3" Gen, GOC + ARm9 APIX, T-CON

Sprite APIX, T-CON

Sprite/Draw/NTSC + FR81S 90nm Flash

Limitations of internal VRAM capacity and bottlenecks like bus speed limit the level of graphic functionality supported, flexibility, pixel fill rate, and maximum display size. If performance is more important than cost, higher-end SoCs based on multi-chip architectures are good choices. These GDCs rely on an external vehicle MCU to handle CAN traffic, power management, and peripherals such as stepper motor controllers. They

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do not have built-in VRAM and program flash memory, but use high-speed VRAM interfaces to support high performance. Some application segments—notably automotive—have to keep up with the high-end graphics that are common in smart phones. Designers must ensure that the GDC can create fluid, crisp graphics and that the system responds quickly to user inputs. Thus, the GDC must not impose bottlenecks in the system that create a lag in delivering the desired experience to the end user.

For basic to mid-level applications, a true single chip SoC may be suitable. For high-end applications, such devices will not provide sufficient performance, and a high-end (multi-chip architecture) SoC with external VRAM and flash memory will be needed. If the product’s display accommodates 24-bit RGB input, a GDC with 24-bit RGB output helps avoid the banding effect (abrupt changes between shades of the same color). The use of 24-bit color ensures smooth-looking graphics. Otherwise, the application may need a dithering function in the GDC for neutralizing the banding effect. Dithering applies randomized noise to the frame buffer to prevent the banding effect due to limited color depth. While smooth, flashy graphics always have appeal, applications such as industrial electronics equipment that prioritize rugged design and ease of use can get by just as well with more basic graphics functionality. Lower-end GDCs offer surprising performance for many uses without inflating the bill of materials.

GRAPHICS CONTENT: STATIC OR DYNAMIC? The choice of GDC also depends on the nature of the graphics content. If the content is static and can be pre-determined, a low-cost GDC such as a sprite engine may suffice. Pre-rendered graphic bitmaps can be stored in the Sprite GDC’s external

TECH ARTICLE flash memory. Such GDCs are very good at handling different color formats (those CPU CPUusing Flash a color lookup table or those having actual pixel values in the frame buffer) and can also VRAMUse handle transparency and alpha blending. of a low-overhead compression scheme, such as RLD (Run Length Decoder), canPeripherals greatly GDC reduce storage requirements for pre-rendered graphics, thus reducing cost. Other applications need dynamic graphics content that is determined on the fly, such as maps or random animation. These True Single Chip SOC for applications requireBasic a GDC that has a fully Level Implementation functional pipeline capable of rendering 2D or 3D models with texture maps. The application may also benefit from the use of functions such as hardware lighting and fogging. For more complicated tasks, a graphics engine CPU with shaders provides greater flexibility. Flash Using a flexible display controller simplifies the work of graphics implementation and supports better graphics. Specifically, graphics development is significantly easier with a flexible layering scheme and support for multiple layers and alpha planes, as well as a variety of color depths. Then there is a choice between 2D and 3D graphics. Using 3D graphics impacts performance and features required from a GDC. For example, 3D applications demand higher rates of vertex processing than 2D applications, along with functions such as perspective correction for texture maps and “mip mapping” needed for 3D graphics. Mipmaps are optimized and resized version of the main texture map that are stored along with the main texture map. They are very

useful in enhancing performance by helping avoid the need to resize the main texture map Periphera CPU on the fly. CPU Flash Just adding the z coordinate for 3D graphics significantly increases processing requirements. Two-dimensional graphics rendering is much simpler, and if the content is static, it can be pre-rendered, as discussed earlier. In the cases of dynamic 2D or 3D content, a graphics engine GDC VRAM+ with a full pipeline will be needed CPU RAM

LEGACY SUPPORT & STANDALONE GDC REQUIREMENT

Some applications must reuse the CPU from previous designs to support Multi-chip legacy requirements and cannot just be designed from theSolutuion ground for up. These applications can often make good use high of standalone GDCs level implementatio that do not have built-in CPUs and can communicate with the legacy CPU via a memory, PCI, or PCI Express bus. This approach enables a scalable design with a variety of performance levels and feature sets. Other applications require the display to be located remotely from Peripherals CPU the GDC. A high-speed serial bus such as APIX is needed in such cases to transmit the video to the display. This configuration allows use of a client or a server architecture, in which the GDC acts as the server and the display as the client. Developing client and server systems independently helps reduce software and qualification costs on the GDC VRAM+ server side because one PCB can be scaled for use across an entire CPU RAM product line. Such an implementation is highly effective if the highspeed serial output functionality is integrated in the GDC. As shown below, Fujitsu offers a wide range of GDCs that span the spectrum of application categories from high to basic. In each catHybrid approach to balance egory, Fujitsu offers an SoC that integrates a CPU, GDC, and peripherals. cost and performance These standalone GDCs are viable options if the system is not being put together from the ground up and there is some legacy component in the system that needs to be preserved. The range of today’s GDC capabilities makes device selection a crucial part of application development. This selection process is easier thanks to a variety of GDC options tailored to meet various application segments. These GDC choices are feature rich, proven in the industry, competitive, and cost effective. ■

High-Quality Display/UXGA

Ruby MB86298 Carmine MB86297

Meter & Display/QVGA

OpenGL ES2.0 Open VG 1.0 SGX,IRIS + CortexA9

Emerald-L Jade Family MB86R0x

Middle-Quality Display/WVGA

OpenGL 1.1 PCI, Dual Video In and OutS

OpenGL ES2.0 Open VG 1.0 SGX,IRIS

3" Gen, GOC + ARm9 APIX, T-CON

Coral-Q, -B, -PA

Lime, Mint, Scarlet

Indigo MB88F332

Sprite APIX, T-CON

Sapphire MB91590

Sprite/Draw/NTSC + FR81S 90nm Flash

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Get the Datasheet and Order Samples http://www.intersil.com

Power Factor Correction Controllers ISL6730A, ISL6730B, ISL6730C, ISL6730D The ISL6730A, ISL6730B, ISL6730C, ISL6730D are active Features power factor correction (PFC) controller ICs that use a boost topology. (ISL6730B, ISL6730C, ISL6730D are Coming Soon.) The controllers are suitable for AC/DC power systems, up to 2kW and over the universal line input.

The ISL6730A, ISL6730B, ISL6730C, ISL6730D are operated in continuous current mode. Accurate input current shaping is achieved with a current error amplifier. A patent pending breakthrough negative capacitance technology minimizes zero crossing distortion and reduces the magnetic components size. The small external components result in a low cost design without sacrificing performance. The internally clamped 12.5V gate driver delivers 1.5A peak current to the external power MOSFET. The ISL6730A, ISL6730B, ISL6730C, ISL6730D provide a highly reliable system that is fully protected. Protection features include cycle-by-cycle overcurrent, over power limit, over-temperature, input brownout, output overvoltage and undervoltage protection.

• Reduce component size requirements - Enables smaller, thinner AC/DC adapters - Choke and cap size can be reduced by 66% - Lower cost of materials • Excellent power factor over line and load regulation - Internal current compensation - CCM Mode with Patent pending IP for smaller EMI filter • Better light load efficiency - Automatic pulse skipping - Programmable or automatic shutdown • High reliable design - Cycle-by-cycle current limit - Input average power limit - OVP and OTP protection - Input brownout protection

The ISL6730A, ISL6730B provide excellent power efficiency and transitions into a power saving skip mode during light load conditions, thus improving efficiency automatically. The ISL6730A, ISL6730B, ISL6730C, ISL6730D can be shut down by pulling the FB pin below 0.5V or grounding the BO pin. The ISL6730C, ISL6730D have no skip mode.

• Small 10 Ld MSOP package

Two switching frequency options are provided. The ISL6730B, ISL6730D switch at 62kHz, and the ISL6730A, ISL6730C switch at 124kHz.

• TV AC/DC power supply

• Desktop computer AC/DC adaptor • Laptop computer AC/DC adaptor • AC/DC brick converters

100

VLINE

Applications

VOUT

EFFICIENCY (%)

VCC ISEN

GATE

ICOMP

GND

ISL6730

VIN

ISL6730A, SKIP

80 ISL6730C

75 70

COMP BO

VREG

FIGURE 1. TYPICAL APPLICATION

40 60 OUTPUT POWER (W)

100

FIGURE 2. PFC EFFICIENCY

TABLE 1. KEY DIFFERENCES IN FAMILY OF ISL6730

February 26, 2013 FN8258.0

VERSION

ISL6730A

ISL6730B

ISL6730C

ISL6730D

Switching Frequency

124kHz

62kHz

124kHz

62kHz

Skip Mode

Yes-Fixed

Intersil (and design) is a registered trademark of Intersil Americas Inc. Copyright Intersil Americas Inc. 2013 All Rights Reserved. All other trademarks mentioned are the property of their respective owners.

Technology You Can Trust

Avago Technologies Optocouplers

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optocouplers deliver outstanding performance on essential safety and deliver exceptional High Voltage protection for your equipment. Alternative isolation technologies such as ADI’s magnetic or TI’s capacitive isolators do not deliver anywhere near the high voltage insulation protection or noise isolation capabilities that optocouplers deliver. For more details on this subject, read our white paper at: www.avagoresponsecenter.com/672

PULSE

Flexible Display and their Applic Alex Toombs Electrical Engineer

onsumer electronics today largely interact with users via screens, be they touchscreens or screens with other means of inputs. Much

has been made about â&#x20AC;&#x153;retinaâ&#x20AC;? displays, wherein the pixel density of the screen is high enough that one cannot distinguish between individual color pixels from a reasonable distance.

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TECH ARTICLE

y Technologies cations

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ortable computing devices like phones and tablets carve out larger portions of electronic market share every day, demanding more powerful screen technologies in the process. While leading tech companies and Kickstarter projects alike push for wearable computing as a new growth field, the technology is not yet commercially viable to make flexible screens. Eventually, the technology promises to offer wrap-around screens, enabling wristwatches and other devices with full color screens that can be straightened out for use as a traditional slate tablet, but for now, current generations of phones have screens that break when dropped from a low height, cracking the glass and possibly the screen underneath it. Flexible OLED screens promise to increase durability to extend the lifetime and usability of phones, laptops, tablets, and other devices.

What Are OLEDs? Many of the innovations weâ&#x20AC;&#x2122;ve experienced over the last decade would be impractical without the change from Cathode-Ray Tube (CRT) monitors to the plasma and LCD monitors that are so ubiquitous today. It makes sense that the change to new broadcasting and display technologies would bring about innovations unheard of even a decade ago. Amidst the sea of technologies like IPS displays, 4K television, and 3D in-home entertainment, however, the only truly revolutionary design change is that of using OLED screens. OLEDs, or Organic Light Emitting Diodes, are semiconductor devices that work using organic materials as opposed to gallium arsenide and other compound semiconductors necessary for traditional LEDs. OLEDs work without the need for a backlight,

Figure 1: Bilayer Organic LED Cell (courtesy of Wikimedia user Rafal Konieczny)

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Figure 2: Flexible OLED with Voltage Applied (courtesy of Wikimedia user meharris)

which allows for deeper blacks to be shown, and also greatly increases power efficiency. This is in contrast to an LCD screen, wherein a backlight is continuously on, producing light that is then filtered through liquid crystal screens. Additionally, OLED screens can be printed on a substrate like plastic using technology very similar to that of inkjet printers. While this is currently prohibitively expensive, OLEDs are already in use in some mobile phones and other products as of the last decade As manufacturing scales up, we can only expect that OLEDs will take more market share, especially as newer products are released that take advantage of the technologies’ strengths.

Typical OLED Composition OLED construction is in some ways similar to that of organic solar cells, though they use different materials in achieving their respective ends. Typically, an OLED cell is comprised of an organic material betwe—en and anode and cathode, which is then deposited on a

substrate like plastic. Organic materials used in OLEDs are denoted “semiconductors” because their conductivity ranges from total insulation to high levels of conductivity, depending upon the voltage applied across them. Whereas typical semiconductors like silicon or gallium arsenide have valence and conduction bands wherein electrons and holes travel, organic semiconductors work by exchanging electrons between neighboring highest occupied orbitals and lowest unoccupied electrons. A typical bilayer OLED cell is shown in Figure 1.

Theory Behind OLEDs When a voltage is applied across the cell, a current flows to the anode as electrons are freed from the highest occupied orbit and move into neighboring lowest unoccupied orbits, much in the way that electrons and holes are generated in traditional semiconductor devices under bias. Depending upon the bandgap of the semiconductor, light of a certain wavelength is emitted as electrons relax back into lower orbitals. These cells are Visit: eeweb.com

PULSE “ One of the greatest advantages of OLED cells is that they can be printed on durable substrates like plastic, allowing them to be used as flexible screens that can be wrapped and bent without worry.” on the order of five percent efficient when talking about quantum efficiency, though there are many efforts underway to make these cells more efficient to further reduce cell power consumption. More expensive devices that use multiple layers, collectively referred to as heterojunction OLED cells, can reach quantum efficiencies of close to twenty percent now.

Advantages and Applications of OLEDs One of the greatest advantages of OLED cells (that is just now being realized) is that they can be printed on durable substrates like plastic, allowing them to be used as flexible screens that can be wrapped and bent without worry. Working prototypes have been demonstrated for the last year or two, with Samsung debuting their flexible displays at CES 2013 this January to the awe of reporters on the site. As companies like Google create next generation computing eyewear and Pebble e-Watches raises hundreds of times more money than they asked for, it is clear that consumers are asking for widespread flexible screens. Now, companies have to figure out how to effectively produce them on a wide scale. Using inkjet printers, manufacturers have developed techniques that deposit OLED material upon flexible plastic sheets. As manufacturing methods grow more widespread, the price promises to drop below even what we currently pay for LCD screens. An example of an OLED printed on flexible plastic is shown as Figure 2.

Challenges to OLED Manufacturing OLEDs are not a miracle technology and still require some innovation before they can achieve wide scale success. The organic cells themselves are subject to degradation due to repeated stress, moisture, and heat, all of which can result from being handled as part of consumer electronics. Additionally, like some solar cells, OLEDs use a brittle translucent conductive material called indium tin oxide

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(ITO) in fabricating the anodes of the device. Other conductive metals cause shadowing effects that would block some of the light generated by the devices. ITO is growing ever more rare and costly, and is one of the most delicate elements in the device. Current AMOLED screens are able to use strong glass to protect and encapsulate the devices, but long-term applications of flexible OLEDs will require some materials problems to be solved.

Final Thoughts on OLEDs OLED technology promises to introduce new consumer electronic arenas for the technology giants to compete in, allowing for wearable computers and other devices that were science fiction just a few years ago. While companies like Samsung already use OLED screens in their phones and can even print cells onto a plastic substrate, nobody has solved the durability issues brought up with the repeated stress of plastic sheets. Additionally, manufacturing these cheaply on a wide scale has proven difficult. But when the materials and manufacturing questions are finally answered, we will see a wide new array of flexible screens in our daily lives.

About the Author Alex Toombs received an electrical engineering degree from the University of Notre Dame, concentrating in semiconductor devices and nanotechnology. His academic, professional and research experiences have exposed him to a wide variety of fields; from financial analysis to semiconductor device design; from quantum mechanics to Android application development; and from low-cost biology tool design to audio technology. He recently joined the cloud startup Apcera as a Software Engineer. ■