A new dual power MOSFET with remarkably low on-resistance for this device type was released today by Siliconix. The new TrenchFET, which is intended for use as a safety switch in lithium ion battery packs, offers on-resistance of just 22 milliohms at a 4.5-V gate drive and 30 milliohms at a 2.5-V gate drive. Setting a record for dual device performance in the LITTLE FOOT TSSOP-8, specifications for the new Si6968DQ constitute nearly a third improvement over the previous state-of-the-art device in this package.

To create the new Si6968DQ, Siliconix combined its latest 32 million-cell/inch2 TrenchFET technology with a novel common-drain design which allows a larger active silicon area in the same size package as a standard dual device. Since the MOSFETs used as safety switches in most lithium ion battery packs are connected at the drain by the manufacturer, the Si6968DQ represents an unusual synergy between the possibilities of Siliconix' TrenchFET power MOSFET technology and the demands of a specific application.

"The Si6968DQ is, to the best of our knowledge, the world's first single chip dual vertical MOSFET," said Phil Dunning, Product Marketing Director at Siliconix. "But what cell phone designers will really value is getting the on-resistance they need in a smaller package."

The Si6968DQ, with a height profile of just 1.1 mm, will provide significant space savings compared to other packages typically used in the safety switch application. Unlike many other 2.5-V-rated devices, furthermore, the Si6968DQ features the 12-V gate-source voltage rating that most battery pack manufacturers now consider a necessity.

Every reduction in the battery pack size and weight is a welcome one. This is a very nice breakthrough from Siliconix and the drain improvements fit this application like the perfect glove. That and the combination of the Little Foot package will make this an easy sell for the company. Little Foot was, to me, one of the smartest joint ventures I have seen in recent years (between Siliconix/Temic and Motorola) as packaging design costs skyrocket. And getting such decent on-resistances in such a package entirely justifies the work.

As battery manufacturers get more and more concerned about safety (and there really are a lot of incredibly stupid things consumers do with batteries and battery packs) the 12-V gate-source rating is an essential for the vast majority of uses. The Si6968DQ is in production and is priced at $1.15 for 100,000-piece lots.