Mosfets tailored for Class D audio power amps

23 February 2005 Power Electronics / Power Management

International Rectifier has introduced the IRF6665 DirectFET mosfet for medium power Class D audio amplifiers. These devices have parameters tuned specifically for improved audio performance such as efficiency, low total harmonic distortion (THD) and power density. Applications for Class D amplifiers range from battery-powered portable products to high-end professional amplifiers, musical instruments and car and home multimedia systems.

In addition to application-tuned silicon, IR's DirectFET packaging technology enhances performance in Class D audio amplifier circuits by reducing lead inductance, which improves switching performance and reduces EMI noise. Thermal efficiency enables 100 W operation into 8 Ω without a heatsink. Eliminating heatsinks shrinks circuit size and bulk, giving designers more layout flexibility and reduces amplifier cost.

Critical mosfet parameters determining Class D audio performance and efficiency include device on-resistance, or RDS(on) and gate charge, or Qg.

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