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ADI introduces Class-D audio amps for portable CE

Posted: 22 Aug 2006 ?? ?Print Version ?Bookmark and Share

Keywords:Analog Devices? ADI? SSM2301? SSM2304? Class D amplifiers?

Analog Devices Inc. has introduced two Class-D audio amplifiers designed to meet the low power, small size and growing sound quality requirements of portable electronics. The SSM2301 and SSM2304 Class D amplifiers are designed to efficiently drive speakers in handheld and portable consumer applications by consuming minimal power, employing sigma-delta modulation to reduce EMI emissions, and integrating a filterless topology that eliminates external components, the company said.

"Combining the power-saving and space-saving benefits of Class-D audio technology with ADI's linear IC expertise has enabled a portfolio of audio amplifiers that deliver exceptional sound for a range of applicationsfrom portable devices such as cellular handsets and MP3 players, to thin flat panel advanced televisions and multi-channel surround-sound car stereos," said Steve Sockolov, product line director for precision signal processing at ADI. "While most Class-D amplifiers use some variation of PWM, ADI's Class-D amplifiers use a sigma-delta pulse density modulation (PDM) to reduce the amplitude of spectral components at high-frequencies, thus significantly minimizing EMI emissions."

Efficient power consumption, exceptional audio fidelityThe SSM2301 (mono) and SSM2304 (stereo) devices operate at 85 percent efficiency over a wide range of output power levels. The SSM2301 delivers 1.4W into an 8 ohm load, and the SSM2304 delivers 2W of power into a 4 ohm load. Both devices operate on a single 2.5-5.5V supply, have a micro-shutdown mode with a maximum shutdown current of 20nA, and feature a built-in thermal shutdown and output short circuit protection. The ability to function at very low voltages makes them suitable for applications such as cellular handsets, where the speaker amplifiers are driven directly from the battery voltage, ADI said.

The new Class-D audio amplifiers are housed in tiny 8-lead, 3-by-3mm LFCSP. Board space is further conserved with a filterless topology that eliminates external output filters.

The SSM2301 and SSM2304 have less than 1 percent THD+N when driving peak output loads from a 5 V supply, and an SNR that is better than 98dB. The fully differential input provides excellent 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 already sampling, with production quantities expected this month. They are priced at 55 cents per unit in 1,000-piece quantities. The devices are fully specified over the industrial temperature range of -40C to 85C. An evaluation board with additional measurement filters is also available.

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Related Datasheets
Part Number Description Category
? SSM2301 Filterless High Efficiency Mono 1.4 W Class-D Audio Amplifier Passives - Filters, Oscillators and Resonators
? SSM2304 2 W Filterless Class-D Stereo Audio Amplifier Passives - Filters, Oscillators and Resonators



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