EL SEGUNDO, CA. March 2001 - International Rectifier Corp. (NYSE: IRF) announces two new 20V HEXFET® power MOSFET families designed to increase efficiency by up to four percent in 12V input DC-DC converters. The new IRF3711 and IRF3704 Series devices are designed for multiphase buck converters that power next-generation, GHz-class microprocessors such as the Intel® Pentium™ 4 and AMD® Athlon® in high-end desktop computers and servers.

The 20V devices are also suitable for 12V input point-of-load (POL) buck converters for distributed power architectures in telecom and datacom applications.

Advanced multiphase buck converters typically require two sets of MOSFETs per phase, the synchronous FET and the control FET. Parameters beyond RDS(on) such as gate charge (Qg) and output capacitance (Coss) are optimized for each device for each application. The 20V IRF3711 series is specifically designed for best performance in the synchronous FET application, while the 20V IRF3704 series is designed for best performance in the control FET application. The 20V maximum rating of IR's devices have a sufficient safety margin for 12V-input synchronous buck converters, and improves performance at the same time.

Carl Blake, Technical Marketing, DC-DC Sector, said, "IR's new 20 volt MOSFETs minimize conduction, switching, driver and output losses in 12 volt input synchronous buck converter applications compared to 30 volt MOSFETs traditionally used in this application."

In desktops and servers, the raw AC mains input is converted to a 12V DC output using a conventional "silver box" AC-DC converter. This 12V DC-regulated input is then converted down to the voltage required by the CPU using a synchronous buck converter. Synchronous buck converters demand high efficiency power components in order to provide ultra-clean DC for today's power-hungry GHz-class microprocessors.

For example, when the 30V MOSFETs in a manufacturer's two-phase buck converter for a Pentium 4 system are replaced with IR's new 20V synchronous FET (IRFR3711) and the new 20V control FET (IRFR3704), test results show a four percent efficiency increase. The improved circuit using IR's application-tuned MOSFETs delivered 78 percent overall efficiency at 1.7V and 20A per phase, operating at 220kHz.

"A four percent efficiency increase at 20 amps is significant. Since circuit board space is at a premium, power management systems must provide increased power in the same or smaller footprint," Blake added.

When frequency is increased to 410kHz in the same two-stage converter, IR's MOSFETs deliver 74 percent efficiency at full load, while the competitions' devices go into thermal runaway.

Higher performance processors with additional functionality may require faster current transient response from the DC-DC converter as the CPU ramps up from idle to full power. This can be achieved by increasing the operating frequency of the converter. IR's new 20V MOSFETs will enable this frequency increase while the buck converter continues to operate in the tight thermal envelope required by manufacturers.

Part Number	Package	BVDSS(V)	RDS(on) max @4.5V(mOhms)	ID* (A)	Qg typ. (nC)	Qgd typ.(nC)	Cosstyp.(pF)	Application
IRF3711	TO-220AB	20	8.5	110	29	8.9	1770	Sync FET
IRF3711S	D2Pak
IRF3711L	TO-262
IRFR3711	D-Pak
IRFU3711	I-Pak
IRF3704	TO-220AB	20	13.5	77	19	6.4	1085	Control FET
IRF3704S	D2Pak
IRF3704L	TO-262
IRFR3704	D-Pak
IRFU3704	I-Pak

Pricing and Availability
The new 20V MOSFETs come in a variety of surface mount and through-hole packages, offering the designer several options depending on circuit design and layout constraints.

Samples of the devices are available now and production quantities will be available in March 2001. Pricing in 10,000 piece quantities for US delivery starts from $0.43 each.