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DAC/amp enhances audio quality in mobile apps

Posted: 26 May 2009 ?? ?Print Version ?Bookmark and Share

Keywords:DAC? speaker amplifier? mobile application? quality audio?

Wolfson Microelectronics has begun sampling a single-chip mono DAC and speaker amplifier targeted at improving audio quality in a range of devices such as mobile phones, conference speakerphones, digital radios and PNDs.

Dubbed the WM9081, the device integrates a 2.6W switchable class AB/D speaker amplifier, dynamic range controller and ReTune Mobile 5 band parametric equalizer. The latter has programmable coefficients allowing speaker frequency response compensation and music profiles to be defined by the user.

Wolfson claims audio performance of 92dB SNR in Class D mode and 1 percent THD+N at 2.4W output power into 4? speaker loads.

The company also claimed that compared to typical two-chip solutions, the WM9081 takes up about 30 percent less PCB area and achieves an average 20 percent BoM cost reduction.

David Brown, audio amps product line manager at Wolfson, said the device squeezes out "the absolute best, in terms of performance, intelligibility and noise immunity, from low-cost speakers."

The WM9081 also supports four control interface addresses and four-channel TDM to allow multiple devices to be configured and driven independently. Controlling the device is done via a standard 2-, 3- or 4-wire control interface or by hardware control pins.

In addition, an integrated digital audio interface is said to give system designers several advantages in terms of noise immunity/reduction. Digital input allows the WM9081 to be located close to the speakers in multi-channel systems without the need for long analog connections.

The on-chip register write sequencer helps minimize software development time. A number of signal paths (such as DAC to speaker mode) can be enabled and disabled by just one register write. To do this, the internal sequencer initiates a sequence of pre programmed multiple writes independently within the WM9081, offloading control interface communication between the processor and WM9081.

The part comes in a 28-pin COL QFN package.

- John Walko
EE Times Europe

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