Power Electronics

Power Semiconductors Take the Floor at APEC

Several exhibitors will be unveiling power semiconductor components at the 2006 Applied Power Electronics Conference and Exposition in March.

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At the upcoming Applied Power Electronics Conference and Exposition (APEC), which will be held March 19-23 in Dallas, several power semiconductor vendors will use the event as a forum for introducing their latest ICs and discrete components. Power supply controllers, power MOSFETs and SiC Schottky diodes are among the new parts being introduced and demonstrated at the show. These components exemplify some of the ongoing trends in controller circuit design, functional integration and device packaging. They also highlight some of the application areas in consumer electronics products and communications, and specific requirements such as energy efficiency, which are driving power component development.

One example comes from National Semiconductor (booths 8 and 9), which will be introducing and demonstrating two new power ICs. A Power-over-Ethernet (PoE) device, the LM5072 integrates a programmable power interface port and a PWM controller, and allows designers to operate PoE appliances at higher power levels than IEEE 802.3af standard devices. Since many emerging PoE applications require power that exceeds the limit of the existing standard (12.95 W), the LM5072 was designed with programmable current limiting that allows it to draw up to 25 W from a PoE-enabled port.

When the LM5072 is designed into standard 802.3af PDs, the current programming resistor can be disconnected to switch the LM5072 to the default mode with its 375-mA maximum current draw. The LM5072, which has a maximum input voltage rating of 100 V and a current rating of 800 mA, also supports applications that accept power from auxiliary sources.

National Semiconductor also will be unveiling the latest member of its high-voltage LM5000 controller family. The LM5035 is a 100-V half-bridge controller that offers a high level of integration and reduced solution size. The LM5035, which integrates primary-side and secondary syncFET drivers, targets consumer electronics, telecom, data communications, industrial, distributed power and battery-operated applications. For more details, see www.national.com.

With its introduction of the NCP1337 PWM current-mode controller, ON Semiconductor aims to simplify the design of quasi-resonant power supplies (Fig. 1). The NCP1337 targets power supplies in notebook ac-dc adapters, off-line battery chargers, consumer electronics such as DVD players, set-top boxes and televisions, and any application where efficiency and low EMI signature are needed.

The NCP1337 combines a true current-mode modulator and a demagnetization detector, which ensures full borderline/critical conduction mode in any load/line. The device eliminates the need for an external signal by providing internal transformer core reset detection. Switching frequency is internally limited to 130 kHz to facilitate compliance with EMI-conducted emission standards, the lowest frequency limit being 150 kHz.

By monitoring the feedback pin activity, this controller enters ripple mode as soon as the power demand falls below a predetermined level. As a result, the standby power of a 160-W CRT television can be reduced to less than 1 W, while adapter no-load consumption can match the most strenuous requirements. Because restart is softened by an internal soft-start and the controller's switching frequency cannot fall below 25 kHz, no audible noise is emitted.

The device will be offered in both 7-pin SOICs and PDIPs and priced at $1.04 per unit in 2500-unit quantities. For additional information or samples, visit www.onsemi.com.

Freescale Semiconductor will introduce a new member of its QUICCSupply family of power devices, which are tuned for PowerQUICC communication processors. The MC34703 QUICCsupply 3 (QS-3) is a dual-output power supply comprised of a 10-A synchronous buck converter and an LDO. It employs unique packaging technology to integrate high-current MOSFETs and control die in a compact 33-pin PQFN package (Fig. 2).

The MC34703 QS-3 is well suited for high-end networking applications using the PowerQUICC III processors, but also supports a number of other advanced microprocessors. Key features include power sequencing, programmable output (through the I2C bus, enabling software adjustment of the output voltage), reset and watchdog functions. Unit pricing in quantities of 10,000 is $2.97. For more information, see www.freescale.com.

Texas Instruments (booths 97 and 98) will highlight several key areas: digital power technology, its latest advancements in “green-mode” control and extensions of its family of wide-input voltage TPS40K dc-dc controllers. The newest members of this family are low pin count, cost-optimized versions of the TPS40K products that are meant to extend the controller family's use in new applications such as set-top boxes, disk drives and servers.

These controllers offer several options for input voltage range. The most notable is the TPS40200 with its extremely wide 4.5-V to 52-V input voltage range. This controller is a nonsynchronous voltage-mode controller with built-in 200-mA FET driver. The TPS40200 generates outputs as low as 0.7 V. Other new models offer input ranges of 4.5 V to 15 V, 2.25 V to 5.5 V, or 4.5 V to 8 V. For more information, see www.ti.com.

Another vendor, Philips Semiconductor, will debut the two newest additions to its energy-efficient GreenChip family of switched-mode power supply controllers. For more details, see www.semiconductors.philips.com.

In the discrete power semiconductor area, Vishay Siliconix (booth 3) will be among the companies introducing new devices that exploit recent packaging innovations. The company will unveil the first 20-V power MOSFETs in its PolarPAK package, which permits double-sided cooling to reduce thermal resistance, package resistance and package inductance. The new devices are aimed at systems requiring high-efficiency dc-to-dc conversion, but which also want the convenience of a package that can be mounted onto a pc board like a standard encapsulated package (Fig. 3). Vishay Siliconix's PolarPAK has been licensed by both STMicroelectronics and Infineon Technologies.

Vishay Siliconix also will be unveiling a series of 25-V MOSFETs designed to prolong battery life in notebook computers. The new MOSFETs offer an on-resistance of 2.6 mΩ at a 4.5-V gate drive. That value of RDS(ON) is said to be 20% lower than that of the 30-V MOSFETs most often used for powering CPU cores.

Packaged in PowerPAK SO-8s and in standard SO-8s, these new devices include both high-side and low-side options for dc-to-dc conversion. For more information, see www.siliconix.com.

Infineon Technologies plans to announce the second generation of its high-voltage silicon-carbide (SiC) Schottky diodes and extensions to its MOSFET product line. The new diodes combine the most desirable attributes of high-voltage SiC Schottky diodes and pn-diodes without reducing efficiency. The two new MOSFET families lower RDS(ON) and increase avalanche ruggedness for the best cost-performance ratio. For more information, see www.infineon.com.

For more details on the components described here, contact the vendors. Or for more information on APEC,see www.apec-conf.org.

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