Analog Devices introduced two Class-D audio amplifiers. The SSM2301 (mono) and SSM2304 (stereo) devices operate at 85 percent efficiency over a wide range of output power levels. The SSM2301 delivers 1.4 W into an 8 ohm load, and the SSM2304 delivers 2 W of power into a 4 ohm load. Both devices operate on a single 2.5 V to 5.5 V supply, have a micro-shutdown mode with a maximum shutdown current of 20 nA, and feature a built-in thermal shutdown and output short circuit protection.

The amplifiers are housed in 8-lead, 3 mm × 3 mm lead-frame chip-scale packaging (LFCSP). Board space is further conserved with a filterless topology that eliminates external output filters. The SSM2301 and SSM2304 have less than 1 percent total harmonic distortion plus noise (THD+N) when driving peak output loads from a 5 V supply, and a signal-to-noise ratio (SNR) that is better than 98 dB. The fully-differential input provides rejection of common-mode noise on the input. The amplifiers also include click-and-pop suppression circuitry that reduces audible noise on activation and deactivation.

The SSM2301 and SSM2304 Class-D audio amplifiers are sampling now, with production quantities available in August 2006, and are priced at $0.55 per unit in 1,000-piece quantities. The devices are fully specified over the industrial temperature range of –40 degrees C to +85 degrees C. An evaluation board with additional measurement filters is also available.