Reference Design Delivers Compact 120-W Class D Amplifier

The IRAUDAMP3 Class D audio reference design offers a complete six-channel 120-W half-bridge audio power amplifier without a heatsink and in a footprint of only 4.5 sq. in. The reference design employs an IRS20124S high-voltage IC, which features an internal selectable dead-time generation circuit and is immune to noise and supply voltage fluctuations to help achieve a total harmonic distortion of 0.01% at 60 W and 4-ohm load impedance, and 94% efficiency at 120 W and 4 ohms, single channel. The IC also has built-in bi-directional current sensing and an integrated shutdown function to protect the output MOSFETs when an over-current condition like a short-circuited speaker wire occurs.

Also used in the reference design is the IRF6645 DirectFET power MOSFET. The patented DirectFET packaging technology enhances performance in Class D audio amplifier circuits by reducing lead inductance, which improves switching performance and reduces electromagnetic interference. The package’s higher thermal efficiency allows 120-W operation into 4 ohms while eliminating the need for a heatsink. The result is greater layout flexibility and lower overall system cost. Devices in the DirectFET package are RoHS compliant.