Low RDS(ON) Power MOSFET and Schottky Diode

Nov 1, 2009 12:00 PM

USING TRENCHFET® Gen III silicon, the Si4628DY SkyFET® from Vishay Intertechnology offers a maximum R_DS(ON) of 3 mΩ at a 10-V gate drive and 3.8 mΩ at 4.5 V — presented as the industry's lowest on-resistance for such a device from an SO-8 package. The first of the company's monolithic MOSFET and Schottky SkyFET products to use their newest TrenchFET technology, the new Si4628DY SkyFET is designed for applications such as the low-side power MOSFET in synchronous buck converters for notebook core voltage and VRM applications, graphic cards, PoL power conversion, and synchronous rectification in computers and servers.

The on-resistance-times-gate-charge figure of merit, a key indicator of performance in such applications, is said to be 26% better at 10 V and 34% better at 4.5 V than the next-best SO-8 device. The Si4628DY is designed to improve power conversion efficiency at light loads for both mains-powered servers and battery-operated notebooks.

Under light-load conditions, the MOSFET in a power converter is off and current conducts through the Schottky diode. Because the Schottky is integrated with the MOSFET, its forward-voltage drop is much lower than the voltage drop across the intrinsic body diode of the MOSFET, resulting in substantially less power loss when the MOSFET is turned off during dead time in a buck-converter application.

A second improvement results from the lower reverse-recovery charge (QRR) of the Schottky diode compared with the QRR of the body diode of the MOSFET. Vishay Siliconix's SkyFET technology reduces QRR in the device by almost 75% compared with a standard MOSFET body diode to improve converter efficiency at light loads.

Finally, integration of the Schottky into the MOSFET silicon chip eliminates the parasitic inductances that would be present if these were mounted to the PCB as individual components, or if separate MOSFET and Schottky diode components were co-packaged. Samples and production quantities of the Si4628DY are available now, with lead times of 10 to 12 weeks for larger orders. Pricing for U.S. delivery starts at $0.48 in 100,000-piece quantities.
Vishay
Malvern, PA
http://www.vishay.com

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