Power Electronics

Data Points

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APEC Highlights Product Innovation

Known for unwrapping exciting new products and technologies, this year's Applied Power Electronics Conference and Exposition (APEC 2006) was no different. In keeping with its high standards, manufacturers unveiled many new devices that promise to further raise the performance bar for power electronics solutions.

Discrete Power Semiconductors

Toward that goal, gallium nitride (GaN)-based Schottky diodes were unveiled for the first time to give silicon carbide (SiC) a new competitor. Velox Semiconductor (www.veloxsemi.com), a spin-off from compound semiconductor-based components supplier Emcore Corp., disclosed 600-V GaN Schottky diodes with zero recovery time for power-supply applications. According to Velox, these devices are the first GaN Schottky rectifiers on the market.

The developer claims to have achieved performance comparable to SiC diodes, but at a fraction of their cost. According to Velox, its GaN diodes are offered in packages similar to silicon and SiC diodes. The company has developed 2-A, 4-A, 6-A and 8-A GaN diodes for applications such as power factor correction (PFC), switched-mode power supplies (SMPS) and freewheeling diodes.

As an alternative to SiC diodes, Velox believes that GaN brings the benefit of Schottky rectifiers to cost-sensitive power supplies where the use of SiC is prohibitively expensive. Right now, only 600-V GaN devices are being offered. However, other voltages and current ratings are under development.

Meanwhile, SiC proponents continue to refurbish their wares. For instance, Infineon Technologies AG (www.infineon.com) introduced its second-generation (2G) SiC Schottky diodes with far superior performance over the previous generation. Boasting zero reverse-recovery charge with switching behavior independent of forward current, speed and temperature, the new SiC diodes offer significantly improved overcurrent and overvoltage characteristics. Thus, the new SiC diodes target PFC circuits in SMPS applications wherein they promise to cut cost by more than 30% with higher efficiency in smaller size.

Samples of Infineon's new SiC Schottky diodes are available with blocking voltages of 600 V (4 A, 5 A, 6 A, 8 A, 2 × 5 A, 2 × 6 A, 2 × 8 A) in compact TO-220 and TO-252 (DPAK, MSL3) packages.

Another vendor, Fairchild Semiconductor, introduced an upgraded version of its FETBench online design tool (www.fetbench.com), which offers MOSFET device selection, application analysis and a thermal simulation tool. The tool now incorporates a wider range of low-voltage MOSFETs for use in computing and ultraportable applications. The upgraded version also incorporates a powerful SPICE-based suite of simulation tools including the Berkeley Short-Channel IGFET Model (BSIM) version 3.1. This device model improves computational performance and reduces design complexity compared to traditional models.

“Using Fairchild's FETBench, designers can quickly predict device performance curves at different operating temperatures without having to do complex tests in the lab,” says Claudia Innes, director of corporate marketing. “FETBench allows designers to save, recall and share critical design simulations. For example, a designer can simply reload the circuit design as opposed to inputting this information each time the tool is used.”

Circuit Protection Devices

Innovolt, a Georgia Tech VentureLab startup, revealed a patent-pending current-inrush and voltage-surge suppressor (CVSS) that combines voltage-surge suppression and current-inrush surge suppression in a single device to ensure complete, cost-effective power protection of electronic equipment. In addition, the Innovolt CVSS also features advanced diagnostics that enable users to better understand the type and frequency of any power disturbances they are experiencing and their impact on sensitive equipment. Designed for a wide range of industrial, commercial, medical and consumer applications, the CVSS is available as a plug-in model for home and office use, as well as a hard-wired unit for OEMs and systems integrators.

Many isolated switched-mode power supplies, PFC circuits and motor control applications use isolators such as optocouplers, pulse transformers, magneto-resisitive devices or Galvanic isolators for required isolation. But, these traditional isolators are bulky, expensive and offer limited data rates.

Silicon Laboratories (www.silabs.com) has alleviated the limitations of traditional isolators with a new line of CMOS-based digital isolators. Leveraging patented RF coupling techniques with chip-scale transformers fabricated in CMOS, Silicon Labs launched a highly integrated four-channel isolator that flaunts 2500-Vrms isolation and more than 50% faster data rates than existing solutions while consuming only 12 mA per channel at 100 Mbps. Plus, the isolator is insensitive to temperature, supply voltage and aging. In addition, it simplifies board layout.

Controllers and Regulators

A variety of power-supply controllers and switching regulators were introduced at APEC. Color many of these product introductions green, since they frequently address the latest requirements for energy efficiency.

For example, Texas Instruments (www.ti.com) debuted the UCC28600, an 8-pin quasi-resonant green-mode PWM controller. This chip was designed to implement off-line supplies that meet Energy Star/European Union Code of Conduct standards for external power supplies such as ac-dc adapters. The controller also targets bias supplies for LCD monitors, LCD TVs and PDP TVs.

The UCC28600 green-mode controller provides high power efficiency in full- and light-load operating conditions, and decreases power consumption in the no-load standby mode. The controller implements quasi-resonant control techniques, frequency fold-back operation in light-load conditions and features a dedicated pin to disable the PFC stage in standby operation. The UCC28600 also integrates high-level protection features for energy-efficient power supplies up to 200 W, including cycle-by-cycle power limit and overcurrent hiccup restart mode.

Similarly, Fairchild Semiconductor (www.fairchildsemi.com) introduced a PFC controller IC to help designers meet energy-efficiency regulations such as Energy2000, Blue Angel and the EU Code of Conduct. The FAN7528 reduces standby power by as much as 320 mW in SMPS designs under 250 W, such as notebook adapters. In addition to dramatically increasing energy efficiency, the highly integrated FAN7528 saves board space by reducing component count.

The active PFC controller operates in critical-conduction mode (CRM), and unlike conventional current-mode CRM PFC controllers, the FAN7528 integrates a dual-output control function to increase efficiency with a universal ac input. This integrated feature eliminated the need to sense the rectified ac line voltage. By eliminating an input voltage-sensing network, the FAN7528 cuts system power loss to 80 mW compared to alternative controllers that need to sense input voltage.

Another company looking to address efficiency requirements is Royal Philips Electronics (www.semiconductors.philips.com), which unveiled two additions to its GreenChip family of ICs. The Philips GreenChip PC is a chip set featuring an all-in-one design that increases the overall efficiency of desktop PC power supplies beyond 80%. The GreenChip SR is a secondary-control IC for notebook adapters that improves adapter efficiency versus existing designs.

The Philips GreenChip PC introduces a new topology that makes it easier and more cost-effective for PC power-supply manufacturers to comply with energy-efficiency specifications such as 80 PLUS and Energy Star. The technology used in this chip set integrates the standby supply into the main converter, reducing the number of external components required. Local secondary regulation also solves primary-side feedback issues and dramatically improves cross-regulation.

According to Philips, the GreenChip SR (which includes part numbers TEA1761 and TEA1762) is the only secondary-control IC available to integrate both synchronous rectification and primary feedback control functionality, all in one. Used in notebook-adapter designs, the GreenChip SR can help achieve 3% to 5% gains in energy efficiency. The GreenChip SR also offers a wide operating range of 8.5 V to 38 V, minimizing the number of external components required and enabling simpler designs. In addition, the high-driver output voltage (10 V) makes the GreenChip SR compatible with all brands of MOSFETs.

ON Semiconductor (www.onsemi.com) addressed the energy-efficiency requirements of power supplies used in LCD TVs. Rather than introducing a new IC, the company unveiled its fourth GreenPoint reference design, which offers a complete design example for a 220-W LCD-TV power supply that consumes less than 1 W of standby power. This flat-screen TV design addresses all the functional blocks of the power supply, while meeting international regulations for low standby power dissipation.

The LCD-TV GreenPoint reference design exploits several of ON Semiconductor's power-management devices and discrete components. Two of the performance enablers are the recently introduced NCP1395 and NCP5181. The NCP1395 is a high-performance resonant-mode controller that offers everything needed to build a reliable and rugged power supply. Its unique architecture includes a 1-MHz voltage-controlled oscillator and protection features with various reaction times that contribute to a safer converter design, without engendering additional circuitry complexity. The NCP5181 is a high-voltage power MOSFET driver that provides two outputs to drive two N-channel MOSFETs. The NCP5181 uses the “bootstrap” technique to ensure proper drive of the high-side power switch.

A complete documentation package for the LCD-TV power supply — including description, schematic, bill of materials, Gerber images and evaluation results — is available at ON Semiconductor's website.

While disclosing its roadmap of high-voltage input regulators and PWM controllers with integrated MOSFETs, Intersil (www.intersil.com) described a high-performance, triple-output controller that provides a single high-frequency power solution primarily for broadband, DSL and networking applications. The ISL6442 integrates complete control, monitoring and protection functions for two synchronous-buck PWM controllers and one linear controller. Input-voltage ripple and total rms input current is substantially reduced by synchronized 180 degrees out-of-phase operation of the two PWMs.

The two PWM buck converters provide simple voltage-mode control. The output voltage of the converters can be precisely regulated to as low as 0.6 V, with a maximum tolerance of ±1.5% over temperature and line variations. Programmable switching frequency up to 2.5 MHz provides fast transient response and small external components. The linear controller provides a low-current output.

The ISL6442 offers voltage-tracking capability. And each controller has soft-start and independent enable functions combined on a single pin. Other features include adjustable overcurrent protection, hiccup-mode overcurrent protection, a power-good signal and thermal shutdown.

For more information on ICs introduced at APEC, as well as power modules and passive components, see the online version of this article at www.powerelectronics.com.

Power IC Designers See Salary Increase

Designers of power ICs experienced a salary increase last year, a trend that was shared by designers of other types of ICs, according to an annual salary survey by technical recruiting firm Analog Group (www.analoggroup.com). The study, “Salary Survey for IC Design Engineers,” found that engineers who specialize in RFICs saw slightly higher pay than those who focused on mixed-signal or power ICs, but that power IC designers still fell on the higher side of the range of salaries reported.

The results of the survey, which are linked to Analog Group's website, showed that in addition to an average salary increase of 8%, IC designers also are receiving sign-on bonuses and restricted stock options. The highest salaries were for positions in the Silicon Valley region.

The survey results reflected that the distinguishing factor among salary ranges was industry experience. Data collected by Matt McGuill of Analog Group indicates that more than 90% of the respondents were advanced degree holders. Bonus amounts also tended to increase with experience, but not as consistently. The Silicon Valley region was also shown to have the highest paid bonuses.

The Analog Group salary survey was initially developed for a power IC client. The original purpose was to determine the market value of several positions within a power management division being created by the client.

PV Market to Reach $2.3 Billion in 2011

The market for thin film and organic photovoltaics (PV) will exceed $2.3 billion in the year 2011, according to a recent report by NanoMarkets, an industry analyst firm based in Glen Allen, Va.

The report, “Thin Film and Organic PV: New Applications for Solar Energy,” states that advances in materials and production modalities are enabling new products, including those that integrate PV with building materials and others that provide novel sources of power for cell phones and notebook computers.

The report also noted that companies that use amorphous silicon, nonsilicon inorganics or organic polymers/small molecules are also benefiting from the shortage of crystalline silicon used in conventional PV, and from the availability of government subsidies as well as the ability of PV users to sell excess power to utilities.

The report examines key product sectors that will create revenue opportunities over the next several years. Consumer electronics are projected to be the third-largest market opportunity, according to NanoMarkets. On the materials front, amorphous silicon, the best established of the various thin film PV materials, will represent an $800 million opportunity followed by organic and hybrid organic/inorganic materials and then copper-indium-gallium-selenium intermetallic compound, known as CIS or CIGS.

The report also examines rival research programs and materials for thin film PV, and compares the various marketing and production strategies being employed to create new PV products for the mobile computer and communications, outdoor power, emergency power and other sectors. It also discusses how this new type of PV will impact traditional PV markets. For more information, see www.nanomarkets.net.

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