EL SEGUNDO, CA. March 2001 - International Rectifier Corp. (NYSE: IRF) introduces two new TO-220-packaged HEXFET® power MOSFETs that maximize power density and deliver maximum performance in primary- and secondary-side DC-DC converter circuits.

The new IR devices can replace larger TO-247-packaged devices. The new MOSFETs are specifically designed for high-efficiency, 48V-input isolated DC-DC converters for telecom and datacom systems. The IRFB42N20D is optimized for primary-side circuits, while the IRF3703 is tuned for secondary-side, sub-3.3V output applications.

New Primary-Side MOSFET Replaces Larger Competing Devices
The IRFB42N20D is a 200V MOSFET with a low gate charge (QG) of 103nC. The gate charge reduces switching losses so significantly that it out-performs similar MOSFETs in the larger TO-247 package.

For example, the new IRFB42N20D replaced a competing TO-247 device in a 48V input, 5V output resistor-capacitor-diode (RCD) clamp-forward converter operating at 110kHz. At full load (40A), the IR device in the TO-220 package delivered better than one percent efficiency improvement over the competing solution in the larger TO-247 package.

"The one percent-plus efficiency increase using the new primary-side MOSFET is significant since it is achieved in a smaller package. Increasing power density requirements drive circuit designers to use higher operating frequencies. The low gate charge of the IRFB42N20D is the key enabling factor for faster switching speeds and more efficiency in a smaller package," said Carl Blake, Technical Marketing, DC-DC Sector.

New Secondary-Side MOSFET Enhances Sub-3.3V Applications
High efficiency, low-voltage DC-DC converters use MOSFETs instead of Schottky diodes in the secondary circuits. For sub-3.3V output applications, the IRF3703 has optimized characteristics that improve efficiency in secondary-side synchronous rectification circuits. The IRF3703 is the best performing 30V MOSFET in a TO-220 package, with 2.8milli-ohms device on-resistance, or RDS(on). This is 20 percent lower than the nearest competing device. The IRF3703 RDS(on) performance reduces conduction losses, while the low gate impedance reduces switching and driver losses.

"In multiple-output, isolated converters, circuit board layout is often simplified if the same device can be used in the secondary stages. The IRF3703 is an excellent choice for secondary stage applications, and reduces bill of material line items as well as time to market," Blake added.

According to industry sources, the MOSFET market for isolated DC-DC converters is approximately $150M, with a growth rate of around 17 percent annually.

Device	BVDSS(V)	Package	RDS(on) @ VGS = 10V(milliohms)	ID (max)@ 25°C (A)	QG(nC)	QGD(nC)	Application
IRFB42N20D	200	TO-220	50.8	42	103	48	Primary MOSFET Isolated DC-DC converters
IRF3703	30	TO-220	2.8	75	209	42	Secondary MOSFET Isolated DC-DC converters

Pricing and Availability
Pricing for the IRFB42N20D is US $1.71 each in 10,000-unit quantities, the IRF3703 is US $1.74 each in 10,000-unit quantities. The devices are available immediately.