Speaker boost IC aims to improve sound quality in smartphones

November 15, 2013 // By Graham Prophet
NXP has extended its range of speaker driver ICs with the TFA9895 – its second-generation speaker boost solution – which improves the sound quality of handsets and tablets via a new multi-band compression feature which enhances the way music and voice sound, even at louder speaker volumes.

The multi-band processing feature in the TFA9895 improves audio quality at louder speaker volumes via more stable high-gain audio imaging. The TFA9895 also adds a high-frequency noise gate that improves the sound of poor-quality audio signals. Like its predecessor, the TFA9887, the TFA9895 offers a completely integrated small speaker driver, including integrated processing and an on-board 5-V DC/DC converter, as well as complete protection against speaker failure. Both ICs can deliver 4W of peak power into a 4-Ohm speaker that is conventionally limited to 0.5W.

The new multi-band algorithm and noise-reduction features complement the existing speaker protection algorithm to provide high-quality sound from small speakers. The feedback-controlled excursion protection prevents distortion caused by hitting the mechanical limits of the speaker, and an advanced clip avoidance algorithm monitors audio performance and prevents amplifier clipping even when the power supply begins to sag. The system allows for bandwidth extension to increase the low frequency response well below speaker resonance. The device can be configured for stereo systems, allowing synchronisation between devices to ensure good stereo imaging.

NXP claims market leading position in speaker boost and protection, with the only IC offering adaptive excursion control which provides real-time, real-world protection even when the acoustic environment changes. Systems using the TFA9895 or other NXP speaker boost amplifiers can greatly improve the sound from small speakers, typically realising gains of 6 to 9 dB in output volume and 12 dB in bass response while also improving system reliability. Alternatively, designers can use the improved performance to further shrink their acoustic systems, resulting in smaller and thinner devices.

As with the previous boost and protection ICs, the entire system is integrated into a single chip, including the CoolFlux DSP high-efficiency class-D amplifier with current sensing and DC-to-DC converter. The advanced, embedded algorithms require no separate licensing. Additional tools allow designers to customise their audio sound quality and choose how to optimise the phone’s performance.

NXP: www.nxp.com/pip/TFA9895UK