WM8956GEFL/V(2007) Просмотр технического описания (PDF) - Wolfson Microelectronics plc

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WM8956GEFL/V
(Rev.:2007)

Hi-Fi DAC with 1W Stereo Class D Speaker Drivers and Headphone Drivers

Wolfson Microelectronics plc 

Preliminary Technical Data

WM8956

DEVICE DESCRIPTION

INTRODUCTION

The WM8956 is a low power audio DAC offering a combination of high quality audio, advanced

features, low power and small size. These characteristics make it ideal for portable digital audio

applications with stereo speaker and headphone outputs such as games consoles, portable media

players and multimedia phones.

Stereo class D speaker drivers can provide 1W per channel into 8Ω loads. BTL configuration

provides high power output and excellent PSRR. Low leakage and pop/click suppression

mechanisms allow direct battery connection, reducing component count and power consumption in

portable battery-powered applications. Highly flexible speaker boost settings provide fully internal

level-shifting of analogue output signals, allowing speaker output power to be maximised while

minimising other analogue supply currents, and requiring no additional components.

A flexible input configuration includes support for two stereo microphone interfaces (single-ended or

pseudo-differential) and additional stereo line inputs. Up to three stereo analogue input sources are

available, removing the need for external analogue switches in many applications. Boost amplifiers

are available for additional gain on the microphone inputs.

The stereo DACs are of hi-fi quality using a 24-bit, low-order oversampling architecture to deliver

optimum performance.

The DAC output signal can be mixed with analogue input signals from the line inputs or bypass

paths. This mix is available on speaker and headphone/line outputs.

The WM8956 has a configurable digital audio interface where digital audio playback data is fed to the

DAC. It supports a number of audio data formats including I2S, DSP Mode (a burst mode in which

frame sync plus two data packed words are transmitted), MSB-First, left justified and MSB-First, right

justified, and can operate in master or slave modes. In PCM mode A-law and µ-law companding is

supported.

The SYSCLK (system clock) provides clocking for the DACs, DSP core, class D outputs and the

digital audio interface. SYSCLK can be derived directly from the MCLK pin or via an integrated PLL,

providing flexibility to support a wide range of clocking schemes. All MCLK frequencies typically used

in portable systems are supported for sample rates between 8kHz and 48kHz. A flexible switching

clock for the class D speaker drivers (synchronous with the audio DSP clocks for best performance)

is also derived from SYSCLK.

To allow full software control over all its features, the WM8956 uses a 2 wire control interface. It is

fully compatible and an ideal partner for a wide range of industry standard microprocessors,

controllers and DSPs. Unused circuitry can be disabled via software to save power, while low

leakage currents extend standby and off time in portable battery-powered applications.

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PTD, July 2007, Rev 2.1

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