Power MOSFETs built in Vishay Siliconix's TrenchFET process claim a 60% lower figure of merit (FOM) than existing devices. The WFET power MOSFETs feature R(DS)ON × Qgd FOMs ranging from 135 to 165 at VGS = 4.5 V. These transistors' thicker gate oxide at the bottom of the silicon trench lowers Crss by two-thirds, yet it doesn't significantly affect on-resistance. In addition, the company's proprietary techniques allow for further increases in cell density to lower on-resistance.
The company unveiled four WFET devices meant for high-side operation in dc-dc converters powering notebook CPU cores. These 20-V rated devices handle 20 A (Si4390DY and Si7390DP) and 40 A (Si4392DY and Si7392DP) of output current. They come packaged in the company's Little Foot and PowerPAK SO-8s. For a summary of specifications, go to www.wallstcom.com/vishay/WFET.htm. Now available, these MOSFETs start at $0.55 in 100,000-piece quantities.