Metal oxide semiconductor field-effect transistors (MOSFETs) have been crucial to the continuing advance of computers, cell phones, game systems, MP3/video players and other electronics. Designers use MOSFETs to make ever-smaller devices, to reduce manufacturing costs, and to reduce power consumption and heat emission while improving battery life and device performance.
Engineers face several challenges when they use discrete MOSFET components in their designs. Circuit board layouts can become difficult when a designer must connect three or four separate components.
The hunt for optimal layouts can result in products that are larger than desired, as well as production and development times that run over schedule. On the manufacturing level, the need for a great deal of discrete components can increase warehouse and inventory management costs and increase the time it takes their employees to select and qualify components.
Furthermore, a chain of discrete components can easily result in poor performance due to parasitic power drains. The more components a designer includes, the greater the chance that one of them will break. From a consumer’s perspective, overuse of discrete components can result in products that are too big for popular tastes and unreliable for peoples’ needs.
Every day, engineers are running up against the limitations of discrete components. And ultimately, many have discovered that there are design challenges that simply can’t be met with a series of discrete FETs, diodes, and controllers. How can designers continue to create electronics that feature better optimization and performance? The solution is to take standard MOSFETs and integrate new features into them to create better components.
Integration advantages
What kind of new performance advantages can designers find in integrated MOSFETs? A single integrated MOSFET can include the full functionality of analog controllers and drivers plus any of many different kinds of FETs and transistors. Such integration can synergistically provide a far greater range of functionalities than discrete products alone.
Designers working in a wide range of electronics industries can make use of integrated MOSFETs. More and more companies are using them in consumer electronics such as DVD players, satellite TV receivers, high-definition LCD and plasma televisions, stereos, game systems, and a wide range of electronic toys.
Most designers would intuitively realize the need for integrated solutions in computers (especially notebooks and ultra-mobile PCs and computer peripherals such as modems and routers), but they are also highly valuable in GPS navigation systems, remote health monitors, casino games, robots, military communications and navigation systems, and even casino games.
Integrated MOSFETs are ideal for use in portable battery-powered electronics, everything from cell phones, PDAs, and media players to flashlights, testing equipment and barcode scanners. Because batteries are heavy, increasing the power efficiency of portable electronics is one of the most important challenges facing designers who seek to make smaller, lighter devices. In cell phones, where component space and performance is critical, improving battery life by 1% can result in 5 more minutes of talk time for the user. A similar power efficiency/use-time ratio applies to notebooks computers and media players.
Therefore, integrated MOSFETs that combine drivers, buck converters, buck controllers, and FETs can be extremely useful to designers. These integrated devices are compact, thin, require little heat-sinking, and are much more cost-effective than discrete components. Better yet, they can be highly power-efficient.
Integrated solutions
Several companies are producing integrated MOSFET solutions. For instance, Fairchild Semiconductor’s TinyBuck is the industry’s smallest 6-A synchronous dc/dc buck converter solution and has the widest VIN range (3.0 to 24 V). Its low-profile MLP package (which is available in a lead-free design) replaces one buck controller, two drivers, two FETs, and one boot diode, requiring 50% less space than comparable design solutions using discrete components (see Fig. 1 ). TinyBuck is intended for a wide range of applications, from entertainment electronics to portable medical equipment to notebook computers and blade servers.
Fig. 1. Products such an the TinyBuck from Fairchild Semiconductor have low-profile MLP package which replaces one buck controller, two drivers, two FETs, and one boot diode, requiring 50% less space.
Texas Instruments’ products include TPS40131, which is a two-phase synchronous buck controller with integrated MOSFET drivers. It supports a 5-V output from a 1 to 40-V supply and is intended for use in graphics cards, networking equipment, servers, and other computer and telecommunications equipment.
Intersil’s ISL8510 offers a standard buck controller, integrated boot diode and FETs for power regulation and frequency switching. It can handle a fixed voltage of 5 V or a variable voltage of 6 to 25 V. This general-purpose lead-free package is intended for applications such as handheld devices, wireless LAN cards and compact flash memory cards.
ON Semiconductor manufactures packages such as its NUD3048 FET switch, which combines two MOSFETs for voltage regulation. It is intended for cell phones and other telecommunications applications.
Vishay Intertechnology produces packages that integrate control MOSFETs, synchronous MOSFETs, and driver circuits. The company’s SiC714CD10 and SiC711CD10 can be used to design buck converters in point-of-load devices such as servers and routers.
International Rectifier’s IRF4000 integrates four MOSFETs into a single package intended for use in power-over-Ethernet devices such as switches and hubs. The device can deliver up to 15 W per port, and it takes up only 20% of the space on a 48-port circuit board that discrete PoE MOSFETs would occupy.
Fairchild Semiconductor also manufactures the lead-free Dual Power 56 (FDMS9620), which includes two specialized/optimized MOSFETs in a dual MLP 5 x 6 package. It incorporates an optimal synchronous buck power stage to improve energy efficiency and PCB space utilization. Its integrated, low-switching-loss “high-side” MOSFET is complemented by a low conduction loss “Low Side” SyncFET for optimal efficiency.
Furthermore, the location and positioning of the two integrated MOSFETs in this package are ideally laid out for design engineers. This package is best for regulating power in notebook computers as well as general point-of-load solutions.
Whether engineers need to make their electronics smaller, faster, cooler, or more energy-efficient, integrated MOSFET solutions exist to help them make their products the best they can be. ■
Visit http://mosfets.electronicproducts.com to see full coverage of MOSFETsSponsored by Fairchild Semiconductor • www.fairchildsemi.com
Visit http://mosfets.electronicproducts.com to see full coverage of MOSFET solutions. Fairchild Semiconductor is the global leader in power analog and power discrete technologies delivering energy-efficient solutions for all electronic systems. Recognized as The Power Franchise, Fairchild provides leading-edge silicon and packaging technologies, manufacturing strength and system expertise. In 2007, Fairchild celebrates its “50/10” anniversary, commemorating 10 years as a new company and 50 years in the industry. Known as the “Father of Silicon Valley,” Fairchild developed the planar transistor in 1958––and with it a new industry. Today, Fairchild is an application-driven, solution-based semiconductor supplier providing online design tools and design centers worldwide as part of its comprehensive Global Power Resource. For more information, visit www.fairchildsemi.com.
Sponsored by Fairchild Semiconductor • http://www.fairchildsemi.com
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