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Wolfson powers ahead with AudioPlus strategy

LONDON — Wolfson Microelectronics has started sampling the first device in a planned family of power management products that are part of the Edinburgh, Scotland-based company's AudioPlus strategy.

Dubbed the WM8350, the device integrates an audio codec and power management subsystem to deliver high performance audio, extended battery life and reduced system cost for portable audio and navigation applications.

Julian Hayes, VP of marketing at Wolfson, said over time, the AudioPlus strategy will mean incorporating technologies from recently acquired companies such as Sonaptic Ltd, bought in July 2007 for $24.8 million for its expertise in noise cancelling techniques that can operate at frequencies up to 3kHz, and the earlier acquisition of MEMS microphone design group Oligon Ltd.

“Integration in this area is important, but it has to be integration at the right level, and it has to deliver in terms of lower power, lower cost and smaller form factor. We are not necessarily aiming for a single chip CMOS microphone, that has its design challenges and is not trivial”, Hayes told EE Times Europe .

He added the Sonaptic noise cancelling technology is being integrated into the next generation of AudioPlus devices “as we speak”, and that the company does not foresee any intellectual property issues. Sonaptic, which traces its origins back to the Sensaura audio perception IP developed by Thorn EMI's Central Research Laboratories in the 1990's.

According to Hayes products using the WM3850 will be on sale by the end of this year. “The part is already being designed in by many of our partners in the consumer electronics space.”

The WM8350 is compatible with leading multimedia application processors, and provides a “highly integrated solution without compromising audio performance.”

Compared to using separate codec and power management chips, which typically require two or more additional components, the WM8350 can save up to 25 percent on the device bill of materials (BOM) cost and 50 percent on the board footprint, Wolfson suggests.

Functions include a low power audio codec, on-chip clock generation, six DC-DC converters, four LDO regulators, a battery charger, two white LED drivers and an auxiliary analogue to digital converter (ADC), all in a 7x7mm BGA package.

The part supports six analog inputs, two stereo analogue outputs and two mono line outputs, and can drive headphones directly. The integrated power management functionality and power efficiency is said to be on a par with competitive discrete solutions. A built-in power management controller is responsible for the output voltage settings, start-up sequence and low-power modes for all internal DC-DC converters and LDO regulators.

Four 2MHz DC-DC step-down (buck) converters, can be used to generate the supplies for CPU core, I/O, memory devices and other system peripherals. Each of these converters provides a programmable output of between 0.85V – 3.4V in 25mV steps with peak efficiencies of more than 90 percent using a small external inductor and capacitor. Two 1MHz DC-DC step-up (boost) converters with greater than 90 percent peak efficiencies can be used for backlight displays and generation of +5V supply for USB OTG.

Four 150mA low noise LDO voltage regulators can be used to generate the supplies for the audio CODEC, external PLL and other system functions. Each of these regulators provides a programmable output voltage between 0.9V – 3.3V in 50mV and 100mV steps.

A single-cell lithium battery charger is included which supports programmable target voltage, trickle and fast charge modes and various safety features for the end application.

The WM8350 incorporates thirteen GPIO pins which can be programmed for alternate system functions including system wakeups and enabling low-power operation.

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