FROM EDN EUROPE: 500W Class-D amplifier design
By Graham Prophet -- EDN, February 3, 2005
International Rectifier's IRAUDAMP1 Class-D audio-amplifier reference design gives engineers a preconfigured circuit that delivers 500W of peak power in each of two stereo channels into 4Ω loudspeakers (Picture). It is based on the IR2011S gate-driver IC and uses a pair of IRFB23N15D MOSFETs in each channel's output stage. A self-oscillating pulse-width modulator keeps component count and costs low. The circuit illustrates design points such as protection and pc-board layout. Protection covers overvoltage and overcurrent limits and prevents dc from reaching the speakers and causing damage. The company claims specifications of 0.008% harmonic distortion plus noise, measured with a single tone (1 kHz) at 100W output. With the same signal, efficiency peaks at 93%, driving 350W. The circuit operates from ±25 to ±60V.
The company has also introduced a MOSFET in its DirectFET surface-mount package, also for Class-D audio amplifiers at the medium power level. Circuits you build with the IRF6665 deliver 100W into 8Ω without heat sinking.
International Rectifier, +44 208 645 8003, www.irf.com.
