EL SEGUNDO, Calif. — July 2006 — International Rectifier, IR® (NYSE: IRF), a world leader in power management technology, today introduced a new 30V-synchronous buck converter chipset consisting of the IRF6631 Control MOSFET and IRF6638 Synchronous MOSFET. The pair features IR’s benchmark DirectFET® packaging with double-sided cooling and the latest HEXFET® MOSFET technology to reach higher levels of efficiency and thermal performance at the intermediate current levels (below 18 amps). Applications include advanced notebook and desktop computer, telecom, datacom and general purpose synchronous buck designs where small size, high efficiency, and improved thermal conduction result in increased power density.

“This new DirectFET chipset is an excellent choice for designers seeking very compact and efficient switching in mid-range, 15- to 18-amp power converter applications. In addition to improving efficiency by over 1% in the five- to eight-amp range, the board space savings is almost 50% compared to the typical approaches using three SO-8 devices,” said Jeff Sherman, senior marketing manager of IR’s Portable Computing Solutions.

Each device is tailored to maximize performance in its role within synchronous DC-DC buck converter circuits. The IRF6631 DirectFET Control MOSFET reduces switching losses, while the IRF6638 DirectFET synchronous MOSFET lessens conduction losses and reverse-recovery charge.

The IRF6631 Control FET features a gate charge of 12nC and delivers a 16% reduction in figure of merit of on resistance-gate charge (99.6 mOhmsnC) compared to previous offerings. The IRF6638 Synchronous FET delivers a typical on-state resistance of 3.0 mOhms at 4.5V, a 12% reduction over existing devices while maintaining the same gate charge.

Part Number	Package	BVDSS (V)	RDS(on) max @10V (mOhms)	RDS(on) max @4.5V (mOhms)	VGS (V)	ID @ Tc=25şC (A)	QG typ (nC)	QGD typ (nC)
IRF6638	DirectFET Medium Can	30	2.9	3.9	20	140	30	11
IRF6631	DirectFET Small Can	30	7.8	10.8	20	57	12	4.4

Patented DirectFET Packaging Technology

International Rectifier's patented DirectFET MOSFET packages present a whole new set of design advantages not previously delivered by standard plastic discrete packages. Their metal can construction enables dual-side cooling that effectively doubles the current handling capacity of high frequency DC-DC buck converters powering advanced microprocessors. In addition, devices in the DirectFET package are compliant with the Restriction of Hazardous Substances Directive (RoHS).

Availability and Pricing

The IRF6631 and IRF6638 DirectFET MOSFETs are available immediately. Pricing is US $0.65 each for the IRF6631 and US $1.05 each for the IRF6638, both in 10,000-unit quantities. Prices are subject to change. The devices are RoHS compliant.