Audio amplifiers with Merus technology maximise battery life, says Infineon

In the design of portable and battery-powered audio devices for consumer speaker applications, key criteria are to maximise battery playback time while maintaining audio performance in a compact form and low system cost.

Infineon has integrated its Merus multi-level switching technology into its audio amplifier ICs. The MA2304DNS and MA2304PNS are supplied in a compact 40-pin QFN package and are aimed primarily at battery-powered speakers, Bluetooth / wireless / smart speakers and soundbars, conference speakers and multi-channel / multi-room audio systems.

The MA2304DNS has an integrated and configurable digital signal processor (DSP) and the MA2304PNS has audio limiter and volume control features. Both ICs feature the second generation multi-level-switching class D audio amplifiers with an inductor-less operation. They provide a bridge-tied load- rated output of 2 x 37W and a power supply voltage range of 10 to 20V for high fidelity audio performance. 

The five-level voltage modulation offers a low idle power of 52mW without the need for complex dynamic rail tracking systems, explained Infineon. This is at least five times lower than the traditional class D audio amplifiers, making these devices suitable for battery-powered speaker applications with extended battery life and/or reduced battery cell cost.

At low output power, the efficiency can be higher than 80 per cent offering extended battery life and thermal management in multi-channel products. Multi-level switching also relaxes electromagnetic compatibility (EMC) requirements and enables inductor-less applications at full power range with lower cost. 

In mains powered, multi-channel applications, the reduced and scalable EMI enables industrial designs which would conventionally need a heatsink or a traditional LC filter.

A high order internal feedback loop ensures low total harmonic distortion (THD) and low noise floor for audio performance. The inductor‑less application contributes to the smallest output filtering, avoiding bulky inductors, thus reducing system cost without output power limitations. 

The integrated DSP in the MA2304DNS is highly configurable and can correct imperfections and tune real speaker applications with, e.g., equalisation, limiting, and other similar functions. The MA2304PNS offers a simpler volume control and limiter for systems where an application/connectivity processor does the audio processing.

The Merus MA2304DNS and MA2304PNS 37W second generation multi-level class D audio amplifiers with an inductor-less operation are available in a QFN 6.0 x 6.0mm² package and can be ordered now.

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