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A variety of developments in different fields have shaped motion control, power supply and power system design over the past 30 years. Improvements in power component design as well as manufacturing and innovation in power electronics circuit design and power supply simulation have advanced the state of the art. Some of the most significant developments are highlighted in the timeline.
While the achievements chronicled in the timeline offer markers of the progress that has been made in power electronics, it's important to recall that none of these developments occurred in a vacuum. Application requirements, progress in other areas of electronics, and the business relations between electronic component suppliers and their customers have influenced the advances made in the power electronics field.
When the first issue of Solid-State Power Conversion — today's Power Electronics Technology magazine — went to print, the semiconductor industry was reeling from its first recession. In 1975, the top five global semiconductor suppliers were Texas Instruments, Philips, Motorola, Fairchild and National Semiconductor.
Top customers for these companies included General Motors, Univac, IBM, Rockwell and Motorola. Based on the customers, it is no surprise that automobiles, computers, industrial and telecommunications were key markets for electronics including power electronics. However, key products introduced after 1975 shaped today's power electronics industry.
Computers, Cell Phones and Cars
There is a symbiotic relationship between technology and applications in every industry, and this is equally true in power electronics. It took the invention of the microprocessor and power controlled by discrete semiconductors and integrated circuits to create the desktop PC. IBM released its Model 5150 personal computer in September 1981. Although it was not the first personal computer by any means, it was the first to have the PC name associated with it.
The unit used an Intel 8088 microprocessor operating at 4.77 MHz and sold for $3000. Peripherals included 16K RAM, 640K max, an 80 × 24 text display, optional storage of 160 KB using 5.25-in. disk drives, and cassette and keyboard ports. The 100 millionth IBM PC shipped in July 2004. The need for higher power and different voltage levels drove the Semiconductor Industry Association (SIA) to release its first technology road map in 1992 (see “The SIA Road Map”). Several milestone products are the direct results of meeting the requirements of desktop and portable computers (Fig. 1).
Available technology allowed Motorola to introduce a cellular phone in 1983. When the 2.5-lb DynaTac 8000x went on sale in 1984, it cost almost $4000 and provided a meager 30 minutes of talk time for each charge on its nickel-cadmium battery. Fast forward to the late 1980s flip phone, whose weight and size was just a fraction of the original, to today's Razr V3 that is just a half-inch thick and weighs 3.35 oz (Fig. 2).
The Razr has 400 minutes of talk time and 250 hours on standby, and includes incredibly bright dual color displays, long-range Bluetooth capability, built-in speakerphone, 4x digital zoom camera, games, and options for MP3 player and vibrate mode. This remarkable progress came from technology advancements from a highly successful product. Since the power for many of the features is at different voltage levels, the Razr and other modern cell phones require several dc-to-dc converters and voltage regulators. In addition, the Li-ion battery requires sophisticated battery charging and control. The thinnest packages, including chip-scale packaging, are a necessity in the Razr.
Automotive Drives Power Electronics
Automotive original equipment manufacturers (OEMs) and their electronic suppliers have been a source of innovation during the past 30 years. The impact of automotive goes well beyond vehicles since appliance and industrial companies frequently adopt or adapt technology pioneered for automobiles. The car companies' volumes justify the R&D expenses for semiconductor and other high-investment companies. Once developed, industrial companies can count on a level of quality and reliability as well as cost-effective technology.
As the world's largest car manufacturer, some of General Motors' key electronic systems are worth noting. In 1979, GM introduced its computer-controlled closed-loop carburetor system to meet new federal emissions standards from the Clean Air Act of 1970 (see “Powered by Legislation”). All other major manufacturers introduced their initial version of a microprocessor engine control system in this same time frame. Note that this application of microprocessor technology occurred two years before the IBM personal computer. GM's system had six major features:
- Closed-loop carburetor control
- Air-pump control
- Distributor-based spark-timing control
- Idle-speed control
- Evaporative purge-valve control
- Transmission torque converter-clutch control.
Each one of these system outputs had power control aspects. In 1981, GM was the first OEM to introduce an electronic carburetor. Subsequently, single- and then multiple-injector drivers became a major technology driver for both integrated circuits (ICs) and power MOSFETs.
General Motors' need for higher current drivers led to Motorola's (now Freescale Semiconductor) development of the first automotive smart power IC with an integrated MOSFET and the first qualification of plastic-packaged TO-220 power MOSFET operation at 175°C maximum junction temperature by International Rectifier and Motorola (now ON Semiconductor). Both milestone products were initiated to support GM's ABS-VI motor-controlled antilock brake system that went into production in 1990 for 1991 model year vehicles. Today, almost all power MOSFETs for automotive applications have 175°C ratings.
Powering Today's Consumer Products
In computers, cell phones and even cars, the challenges for power electronics continues to increase with every new generation of product. All of these applications require more efficient power at lower and different voltage levels in less space inside the enclosure. This is true even though the lines blur between a portable digital assistant with camera and cell phone capability, or a cell phone with integrated camera and games, or a car with a Bluetooth connection to cell phone and built-in computer-based navigation system. The next 30 years promise to provide even greater milestones and products for power electronics.
Smart Power and Packaging Concepts
The applications discussed previously have driven the development of many power component technologies. But as in other areas of electronics, the semiconductor-related developments have been critical in propelling power supply, power system and motion control applications to the high levels of performance being achieved today. Within power semiconductors, two major areas of innovation have been in the development of smart power ICs and advances in semiconductor and system-level packaging.
What the industry has come to know today as smart power ICs results from the merging of CMOS and bipolar controls (BiMOS) with a single or multiple DMOS-output devices, attributed by insiders at Motorola (now Freescale Semiconductor) to Tony New. A power BiMOS high-side driver with a bipolar output device was one of Motorola's first products to combine technology to solve a power problem. “The power transistor was a bipolar device and the smarts were in CMOS transistors with some amount of logic and CMOS analog circuits,” recalls John Pigott, designer for Freescale. Published in a paper in the 1984 IEEE Custom Integrated Circuits Conference, the part also known as HSD-28 was used in the production of General Motors' vehicles to control the fuel pump. This is believed to be the first automotive application of smart power IC technology.
GM subsequently defined the requirements for a MOSFET output device called HSD-3. This unit was based on the capability of a fully protected smart power IC with a MOSFET output that Motorola called the MPC1510. The HSD-3 was qualified and shipped in volume in 1990, according to Hak Yam Tsoi. Tsoi was responsible for developing the production SMARTMOS process at Motorola. “In the HSD-3, the 3 referred to the fact that it drove a 3-Ω load,” Pigott says. “The load current was about 4 A and the current limit was about 6.” The unit used an already developed industry-standard 7-pin TO-220.
HSD-3 was a driver in General Motors' ABS-VI antilock braking system. The monolithic unit had an active substrate for the MOSFET and several integrated protection and diagnostic features. Subsequently, updrain technology allowed multiple isolated output devices targeting applications including injector drivers.
The first monolithic motor control with MOSFET outputs resulted from modifying the process, known as SMARTMOS-J, for lower-voltage applications. Canon's EOS auto-focus, single-lens reflex camera introduced in 1987 used one of these units for the rewind and one for the auto focus.
The technology quickly progressed to the first MCU plus power, a level dubbed hyperintegration, which combined an HC05 microcontroller with two DMOS-based H-bridge outputs to control motors such as those in automotive mirrors, which received a patent in 1990 and subsequently appeared in the November issue of PCIM magazine, “Industry's First Monolithic Smart Power Microcontroller Handles Over Six Watts.”
One of the key transitions for power packaging was the move toward surface-mount technology in the mid-1980s initiated by the development of the DPAK power package. At the time, Daniel Artusi, currently chairman and CEO of ColdWatt Inc., a provider of high-efficiency power supplies for the communications and computer industry, was responsible for market development for Motorola Semiconductor Products.
The DPAK was initially defined in Japan but targeted at small signal applications. Motorola ruggedized the package with changes such as an aluminum-wire bond process commonly used for power transistors. Artusi recalls that the first power products such as the MJD340 and MJD350 bipolar transistors were for telecommunication line cards. Later, Motorola also designed the first D2PAK to provide lower on-resistance and higher power capability than the DPAK. Prior to this effort, suppliers or customers cut the tab from TO-220 transistor to provide a larger surface-mount package.
More recent surface-mount packages — such as Motorola's (Freescale's) power quad flat no-lead (PQFN) packaging that isolates the power die from additional circuitry — expand the power and control of smart power products. Packages such as International Rectifier's FlipFET and DirectFET provide recent milestones for highly dense power discrete products packaging (Fig. 3).
When asked his thoughts for milestone packaging achievements, Doug Hopkins, president of DC Hopkins & Associates, a research associate professor in the Electrical Engineering Department at State University of New York at Buffalo, and recognized power packaging expert, proposed that insulated metal substrates (IMS) and laminated bus bars were key packaging accomplishments in the last 30 years.
Other notable packaging innovations include the brick format initially defined by Vicor in 1984. The brick has been a mainstay and basis for advancing power supply packaging for more than 20 years. After the first bricks were introduced, the format was respun into smaller formats like the half-brick (1988) and quarter-brick (1996). By replacing the original full-bricks with half- or quarter-bricks, users could obtain multiple output voltages.
However, concurrent with the introduction of smaller form factors were improvements in isolated dc-dc converter design. As the designs became more advanced, the power and current density achieved by the bricks rose. Consequently, power supply vendors have been able to provide the same levels of current and power output in smaller and smaller brick formats. This progress led to the introduction of the eighth-bricks (2002) and the sixteenth-bricks (2003).
Power Electronics Milestones and Products
Silicon General introduces the industry's first PWM controller IC, the SG1524, which was designed by Bob Mammano.
National Semiconductor introduces the first three-terminal linear regulator designed by Bob Dobkin.
Sprague Electric and National Semiconductor introduce combined power/control ICs.
Bergquist launches Silpad to replace grease and mica insulators.
- International Rectifier (IR) patents the first commercially viable power MOSFET, the HEXFET.
SGS introduces the L296, the first monolithic switching regulator.
RCA's Carl F. Wheatley Jr. and Hans Becke are awarded a U.S. patent for the IGBT (see “Inventing the IGBT” on page 18).
IR launches the first commercially viable high-voltage ICs.
Vicor introduces a dc-dc converter that pioneers zero-current switching, the brick format and high power density (25 W/in3).
Motorola introduces the DPAK as surface-mount power package.
Linear Technology introduces the first bipolar low dropout regulator.
Motorola announces the first monolithic MOSFET motor control.
Multisource Technology, founded by Alex Estrov, commercializes planar magnetics for power supply applications.
IR and Motorola qualify MOSFETs for maximum 175°C TJ for ABS application.
Sony commercializes the first Li-ion battery.
Linear Technology introduces the first synchronous switching regulator.
Siliconix introduces the first trench power MOSFETs.
Power Integrations introduces the first three-terminal integrated high-voltage CMOS off-line switcher.
Maxwell Technologies commercializes ultracapacitors for power storage, producing 1200-F, 2.3-V devices for Honda's Integrated Motor Assist system.
STM introduces the first submicron power IC.
Semtech introduces the first monolithic, multiphase PWM controller.
Power Integrations announces a digital on/off control topology for switching power converters.
National Semiconductor pioneers online simulation and virtual prototyping for switch-mode power supplies.
SynQor introduces the 30-A dc-dc converter using synchronous rectification.
Siemens describes the CoolMOS superjunction FET at the IEEE ISPSD Conference.
IR introduces the FlipFET first wafer-level power packaging.
STM introduces the high-voltage mesh technology reducing on-resistance by three to four times.
iWatt announces a digital power supply controller.
IR introduces DirectFET.
Power-One introduces a nonisolated dc-dc converter using a digital PWM controller.
The SIA Road Map
The Semiconductor Industry Association (SIA) published its first technology road map in 1992. Based on projected improvements forecast by Moore's law, performance of leading-edge integrated circuits such as microprocessors and memory would double within 18 months. To achieve these forecasts, many areas of improvement were required to keep up with higher clock speeds and greater amounts of memory. This included testing, packaging and, of course, power.
In 1999, the forecast for 2005 marked the end of the short-term projection. The long-term forecast for both desktop and portable applications extended out 15 years to 2014, where minimum voltages for maximum power are forecast at 0.6 V for desktop computers and maximum high-performance power with a heatsink will reach 183 W.
Powered by Legislation
Perhaps one of the most easily recognized drivers of technology is government legislation. The U.S. Environmental Protection Agency's Clean Air Act of 1970 spurred the initial development of engine control systems with all of the associated power control elements. Subsequent legislation has made electronic engine controls a continuously improving area for power electronics.
The International Electrotechnical Commission (IEC) PFC (THD) legislation such as IEC 1000-3-2 and IEC 6000.3.2. in Europe, JIS C 61000-3-2 in Japan, and the China Compulsory Certificate (CCC) have resulted in the development of several power-factor correction (PFC) ICs. The U.S. Department of Energy's EnergyStar program represents a number of efforts to make more energy-efficient products. Similar types of programs also exist in several European countries, including Germany's Blue Angel and the Group for Energy Efficient Appliances (GEEA), and all of them strive to reduce power consumption in both active and standby modes. This legislation drove the development of numerous ICs and has led to the more efficient use of power.
Inventing the IGBT
As with many key inventions, researchers working independently sometimes result in more than one person discovering the solution. A well-known electronic industry example is the invention of the integrated circuit by Jack Kilby and Robert Noyce, who both applied for patents in 1959 that were subsequently issued. In power electronics, the IGBT has multiple inventors.
On Dec. 14, 1982, RCA's Carl F. Wheatley Jr. and Hans Becke were awarded U.S. Letters Patent No. 4,364,073: “Power MOSFET with an Anode Region.” Today, it's considered the seminal patent for the IGBT. The patent was filed March 25, 1980.
As noted in the September 2005 issue of Power Electronics Technology (”Advances in Discrete Semiconductors March On,” pp. 52-56): “[Nathan] Zommer helped B. Jayant Baliga commercialize the IGBT in the 1980 time frame. Zommer built the first IGBTs under the direction of Baliga, who invented the device at General Electric R&D labs in Schenectady, N.Y. Together they delivered the first paper on IGBTs in 1981.”
Today, both RCA and GE are part of the power heritage of Fairchild Semiconductor.