WM8758B datasheet(25/90 Pages) WOLFSON

25 / 90 page

Production Data

WM8758B

PD, Rev 4.4, January 2012

DEVICE DESCRIPTION

INTRODUCTION

The WM8758B is a low power audio codec combining a high quality stereo audio DAC and ADC, with

flexible line and microphone input and output processing.

FEATURES

The chip offers great flexibility in use, and so can support many different modes of operation as

follows:

MICROPHONE INPUTS

Two pairs of stereo microphone inputs are provided, allowing a pair of stereo microphones to be

pseudo-differentially connected, with user defined gain. The provision of the common mode input pin

for each stereo input allows for rejection of common mode noise on the microphone inputs (level

depends on gain setting chosen). A microphone bias is output from the chip which can be used to

bias both microphones. The signal routing can be configured to allow manual adjustment of mic

levels, or to allow the ALC loop to control the level of mic signal that is transmitted.

Total gain through the microphone paths of up to +55.25dB can be selected.

PGA AND ALC OPERATION

A programmable gain amplifier is provided in the input path to the ADC. This may be used manually

or in conjunction with a mixed analogue/digital automatic level control (ALC) which keeps the

recording volume constant.

ADC

The stereo ADC uses a 24-bit high-order oversampling architecture to deliver optimum performance

with low power consumption.

HI-FI DAC

The hi-fi DAC provides high quality audio playback suitable for all portable audio hi-fi type

applications, including MP3 players and portable disc players of all types.

OUTPUT MIXERS

Flexible mixing is provided on the outputs of the device. A stereo mixer is provided for the stereo

headphone or line outputs, LOUT1/ROUT1, and additional summers on the OUT3/OUT4 outputs

allow for an optional differential or stereo line output on these pins. Gain adjustment PGAs are

provided for the LOUT1/ROUT1 and LOUT2/ROUT2 outputs, and signal switching is provided to allow

for all possible signal combinations.

OUT3 and OUT4 can be configured to provide an additional stereo or mono differential lineout from

the output of the DACs, the mixers or the input microphone boost stages. They can also provide a

midrail reference for pseudo differential inputs to external amplifiers. OUT3 and OUT4 should not be

used as a buffered midrail reference in capless mode.

AUDIO INTERFACES

The WM8758B has a standard audio interface, to support the transmission of stereo data to and from

the chip. This interface is a 3 wire standard audio interface which supports a number of audio data

formats including:



DSP/PCM Mode (a burst mode in which LRC sync plus 2 data packed words are

transmitted)



MSB-First, left justified



MSB-First, right justified

The interface can operate in master or slave modes.

CONTROL INTERFACES

To allow full software control over all features, the WM8758B offers a choice of 2 or 3 wire control

interface. It is fully compatible and an ideal partner for a wide range of industry standard

microprocessors, controllers and DSPs.

Selection of the mode is via the MODE pin. In 2 wire mode, the address of the device is fixed as

0011010b.

WM8758B Datasheet(PDF) 25 Page - Wolfson Microelectronics plc

WM8758B Datasheet(HTML) 25 Page - Wolfson Microelectronics plc

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