EL SEGUNDO, CA. March 2001 - International Rectifier Corp. (NYSE: IRF) announces the availability of the IRDCSYN2 reference design for the IR1176 application-specific synchronous rectification IC (SRIC). The new IR1176 simplifies and improves isolated DC-DC converters with voltage output down to 1.5V, powering telecom and broadband network servers.

When used with IR DC-DC converter-specific HEXFET® power MOSFETs such as the IRF7822, the IR1176 SRIC enhances 1.5 and 1.8V DC-DC converter efficiency ratings. At 40A, in-circuit efficiency is 86% for 1.8V, and 85% for 1.5V output circuits with 48V input. The new SRIC accomplishes this using a proprietary method of controlling switching transitions of secondary-side MOSFET synchronous rectifiers in a way that minimizes losses associated with body diode conduction.

The IR1176 is a high speed CMOS controller designed to drive N-channel power MOSFETs used as synchronous rectifiers in high current, high frequency forward converters with output voltages equal or below five volts. Schmitt trigger inputs with double pulse suppression allow the controller to operate in noisy environments. The circuit does not require any ties to the primary side and derives its operating power directly from the secondary. The circuit functions by anticipating transformer output transitions, then turns the power MOSFETs on or off before the transitions of the transformer to minimize body drain diode conduction and reduce associated losses. Turn on/off lead time can be adjusted to accommodate a variety of power MOSFET sizes and circuit conditions. The IR1176 also provides gate drive overlap/dead-time control via external components to further minimize diode conduction by nulling effects of secondary loop and device package inductance.

Engineers using the reference design can cut circuit development time by as much as four weeks, since the reference design may be modified to suit a specific application and lead to the development of a final production design.

The IRDCSYN2 reference design board is rated at 3.3VDC and 20A output with an efficiency of 90 percent. The reference design includes a fully-functional synchronous rectification circuit, complete with a bill of materials, schematics, application notes and Gerber file. The reference design board measures 3.25-in. x 2.7-in. x 0.75-in.

Pricing and Availability
The new reference design is available for US $376 each from distributors worldwide.