Review
For this review, we will broadly classify power semiconductors into two main categories: discretes and ICs. For discretes, which are for the most part power MOSFETs, progress was made this year in packaging and integration. A couple of examples of packaging prowess come from International Rectifier (irf.com). Housed in a package that is 50% smaller than the standard SO-8, the IRF6608 was the first of the company's HEXFET MOSFETs to use its new double-side-cooled, surface-mount, 4.8 mm x 3.8 mm DirectFET "S" package. The device's profile is 0.7 mm, compared to 1.75 mm for SO-8. Together with the IRF6618, the MOSFETs make up the smallest control and synchronous chipset for existing and next-generation VRM10.x high-current (105A) synchronous buck converters. In another example of a packaging feat, the company squeezed a 20V dual bi-directional power MOSFET in a common drain configuration into the company's proprietary FlipFET package, making the FET 80% smaller than in a TSSOP-8 package. The IRF6156 FET's small size—including a profile of less than 0.8 mm—addresses the need for increasingly smaller packages in dc/dc converter applications.
As for integration efforts, the TPC8A01 from Toshiba America Electronic Components (toshiba.com/taec) was introduced this year as the first device to integrate two MOSFETs and a Schottky barrier diode onto a single die. The device is manufactured using the company's UMOS III process technology and comes in a standard SOP-8 package measuring 30 mm2 and 1.6 mm thick.
Now let's move to power ICs where there was lots of action this year in packaging and performance. One packaging example is the AnyAdapter ISL6292 IC from Intersil (intersil.com). Housed in thermally enhanced 3 x 3-mm DFN and 4 x 4-mm and 5 x 5-mm QFN packages, the device was introduced as the industry's smallest Li-ion/Li-polymer battery charger. Any-Adapter indicates that the device can accept a wide range of voltage sources.
On the performance side, Sipex (sipex.com) introduced a boost regulator, the SP6648, designed to power either dual-cell alkaline or Li-Ion based battery applications with an efficiency of 94%. The 10-pin MSOP device consumes a quiescent current of 12 µA while delivering up to 400 mA of output current. This combination of high output power and low quiescent current is accomplished by automatically switching from pulse width modulation (PWM) to pulse frequency modulation (PFM) under light-load conditions. Another example is the AAT3123 and AAT3124 charge pumps from Advanced Analogic Technology (analogictech.com). The high-efficiency, low-noise, constant-frequency devices for white LED applications integrate both a 1.5X fractional charge pump and a 1X load switch, with the dual-mode devices said to push efficiency to new levels by only stepping up the voltage when necessary. The 1X load switch allows battery voltage to pass through to the output when sufficient voltage is available and activates the fractional 1.5X charge pump only when the battery voltage is low.
A hot topic for power ICs this year was power over Ethernet. Texas Instruments (ti.com) stepped to the plate in this area with its TPS2370 and TPS2383. This power management chips allows dc power and data to be delivered and sourced over Ethernet cable. Compliant with the proposed IEEE 802.3af standard, the TSP2370 power interface switch manages detection, classification and delivery of dc power to powered devices (PDs) over standard Ethernet twisted pair cable, while the TSP2383 power sourcing equipment power manager (PSEPM) is capable of independently managing power for up to eight Ethernet ports.
—Joe Desposito
Outlook
Take It To The Limit
There's no doubt that the power semiconductor industry has made great strides in the past few years in terms of packaging and performance of both ICs and discrete power devices. Can we expect to see many more breakthroughs in these areas? Common sense says no. But for every problem of heat dissipation, efficiency and space caused by faster processors, stagnant battery technology and shrinking electronics products, the solution promises tremendous awards for the companies that "figure it out." So expect to see gains, even if incremental, in efficiency across the board for power semis and to see innovative packaging and integration that tackles the worst of power related problems, namely heat and size.
—JD
