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CODECs boost audio for stereo headsets, digital cameras

San Diego, Calif.&#8212Two new CODECs from Wolfson Microelectronics are designed to deliver hi-fi stereo quality for stereo headset applications as well as high quality audio for digital camera systems.

The WM8987L, in a 28-pin QFN package measuring just 4-by-4 mm, is said to be the world's smallest CODEC with fully differential-capable headphone driver for wireless headsets and other 'wearable' electronics. Working from a 1.8-volt power supply to provide as much volume as devices using a 3.3-volt source, the WM8987L is designed specifically for Bluetooth Advanced Audio Distribution Profile (A2DP) applications and equivalent alternatives when implementing hi-fi stereo in a wireless headset. Its differential output eliminates the need for output capacitors while providing better bass response and delivering longer battery life.

The 24-bit CODEC features an SNR of 87 dB (A-weighted) for recording and 95 dB for playback at 1.8 volts. On-chip bass boost, tone control and 3-D enhancement improve perceived sound quality. Granular power management disables unused sub-circuits to prolong battery life. Four flexible analog inputs reduce electrical noise through the differential microphone connection. The inputs also support an analog line-in for an on-board FM tuner.

Wolfson's second product, the WM8940 mono CODEC, which cuts device footprint by 40 percent over previous generation parts, is designed to provide enhanced audio record capability in digital still cameras (DSC), camcorders, personal voice recorders and VoIP handsets. The chip, in a 4-by-4 mm, 24-pin QFN package, includes four programmable notch filters with DSP functionality to reduce background noise. These filters come into play for audio recording and playback in zoom and focus-motor applications to reduce noise from wind and mechanical vibration. The chip also includes noise-reduction circuitry to compensate for the high-gain microphone amps usually needed in the typical environment, where the subject is a fair distance away. The chip also has an integrated phase-locked loop (PLL) for sample rate flexibility and a headphone and speaker driver.

Click here for the WM8987L's datasheet, and here for the WM8940's. The WM8987L is $1.71 each in 10k quantities and the WM8940 is $1.74.

The Bluetooth Advanced Audio Distribution Profile (A2DP), also known as the AV profile, defines how high quality audio (stereo or mono) can be streamed from one device to another over a Bluetooth connection .

Wolfson Microelectronics Inc. , 1-858-676-5090, www.wolfsonmicro.com

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