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IR's Power Chipset and Cirrus Logic IC Boost Efficiency and Shrink Audio Amplifiers by up to 75%

Applications for Class D amplifiers range from battery-powered portable audio products to high-end professional amplifiers and musical instruments, as well as car and home audio systems that offer concert-quality sound.

International Rectifier HEXFET® power MOSFETs and gate driver integrated circuit (IC) work with the Cirrus Logic power amplifier controller ICs to boost consumer and professional audio amplifier efficiency and cut losses by up to 80 percent. This breakthrough efficiency improvement allows designers to shrink the size of audio amplifiers by as much as a factor of four. The digital Class D amplifiers work with International Rectifier's devices to enable dramatic improvements in sound quality by delivering better signal-to-noise (S/N) ratio, reducing total harmonic distortion (THD), expanding dynamic range, and enhancing frequency response.

Dr. Skip Taylor, Vice President of PWM Technologies for Cirrus Logic, said, ``IR's application-tuned power management devices are an enabling technology for this Class D audio design breakthrough. The Crystal TrueDigital Class D amplifier technology combined with International Rectifier's IRCS-Series chipsets has overcome the technological barriers that prevented the widespread adoption of Class D amplifiers and offer significant improvements over today's audio amplifiers.''

Bipolar transistors currently used in Class AB audio amplifiers are not suitable for new Class D amplifier topologies, so designers turned to optimized MOSFET technology that makes it possible to deliver the sound quality and efficiency that audiophiles and music professionals require.

Cirrus Logic, the premier provider of chips for the entertainment industry, is leading the Class D revolution and selected International Rectifier to provide the application-specific power chipsets needed for the Class D amplifier output stage.

Technical Details

International Rectifier's IRCS-Series power semiconductor chipsets include the IRCS8101 and IRCS8102 HEXFET power MOSFETs and IRCS8001 gate driver integrated circuit (IC). International Rectifier has leveraged its applications expertise in switching mode power supplies along with its advanced MOSFET technology to develop application-tuned MOSFETs for Class D amplifiers.

In Class D amplifier topologies, which evolved from switch mode power supplies, dead time control is critical to reduce harmonic distortion and provide the highest audio quality. IRCS-Series MOSFETs offer switching speeds up to 1MHz, without any compromise in efficiency, thanks to their low gate-to-drain charge (QGD), output capacitance (COSS) and on resistance (RDS(on)). IRCS-Series MOSFETs minimize conduction and switching losses to improve the efficiency of Class D amplifiers from industry norm of 50% to over 90%.

The low output capacitance and soft and fast recovery diode of the IRCS-Series MOSFETs also significantly reduce distortions in sound output. The IRCS8001 gate driver IC combines most of the functions to drive the MOSFETs in one chip and provides very fast switching speeds and low power dissipation. The IRCS8001 IC is specifically designed for the IRCS-Series MOSFET to deliver the highest performance.

The Cirrus Logic full-bridge and half-bridge TrueDigital Class D power amplifier demonstration boards feature Cirrus Logic's Crystal Sound DSPs and IR application-specific HEXFET MOSFETs and gate driver ICs. The 50-watt power amplifiers are designed for applications such as shelf-top audio systems, audio mini systems, audio/video receivers (AVR), boom boxes, small professional amplifiers and powered speakers.

Enhanced efficiency allows manufacturers to dramatically shrink the size of a typical audio amplifier by a factor of four. The size reduction increases product design creativity, allowing the amplifier to be built into a speaker or other unit, such as set-top boxes and DVD players. A large boom box can be reduced to the size of a portable CD player and still deliver the same sound volume and quality. Increased efficiency also enables battery-powered amplifiers that can run up to three times as long compared to conventional amplifiers.

``With this partnership, Cirrus continues to execute its Total-E(TM) solutions strategy by providing the first members from our TrueDigital Class D amplifier family,'' commented Taylor.

Stephen Oliver, International Rectifier Marketing Manager, AC-DC Products, added, ``International Rectifier audio-optimized IRCS-Series chipsets combine with Cirrus Logic's breakthrough TrueDigital Class D technology to deliver a complete solution that allows easy implementation of small footprint, highly efficient, completely digital Class D amplifiers with high-quality sound.''

Pricing and Availability

Pricing for the International Rectifier IRCS8001 gate driver IC is US $3.55 each, the IRCS8101 is US $1.08 each, and the IRCS8102 is US $1.45 each in 10,000-unit quantities.

About International Rectifier

International Rectifier is recognized as the leading supplier of power semiconductors and systems solutions. IR's patented HEXFET® power MOSFETs, IGBTs and high-voltage ICs make electricity work smarter in industrial automation and controls, automotive electrical systems, consumer electronics, computers and peripherals, telecommunications, lighting and satellite/launch vehicle applications. Visit the IR Web site for more information on International Rectifier products: www.irf.com.

About Cirrus Logic Inc.

Cirrus Logic is a premier supplier of high-performance analog and DSP chip solutions for Internet entertainment electronics. Building on its global market share leadership in audio integrated circuits and its rich mixed-signal patent portfolio, the company targets high-volume audio, video and communications applications. Cirrus Logic sells its products under the Crystal®, Maverick(TM) and 3Ci(TM) brands, as well as its own name. Founded in 1984 in Silicon Valley, Cirrus Logic operates from headquarters in Austin, Texas and major sites located in Fremont, California and Broomfield, Colorado, as well as offices in Europe, Japan and Asia. More information about Cirrus Logic is available at www.cirrus.com.

Trademark Notices

IR® and HEXFET® are registered trademarks of International Rectifier Corporation. All other product names noted herein may be trademarks of their respective holders.

Cirrus Logic®, Crystal® and Maverick(TM) are trademarks of Cirrus Logic Inc. All other product names noted herein may be trademarks of their respective holders.

Contact:

     International Rectifier, El Segundo
     Joe Engle, 310/252-7019
     jengle1@irf.com
       or
     Cirrus Logic
     Molly Muir, 512/912-6324
     mollym@crystal.cirrus.com