WM8955 datasheet(15/43 Pages) WOLFSON

15 / 43 page

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WM8955L

Product Preview Rev 0.4 May2003

SIGNAL PATH

The WM8955L signal paths consists of digital filters, DACs, analogue mixers and output drivers.

Each circuit block can be enabled or disabled separatelyusing the control bits in register 26 (see

“Power Management”). Thus it is possible to utilise the analogue mixing and amplification provided

bythe WM8955L, irrespective of whether the DACs are running or not.

The WM8955L receives digital input data on the DACDAT pin. The digital filter block processes the

data to provide the following functions:

•

Digital volume control

•

Tone control and Bass Boost

•

Digital Mono Mix

•

Sigma-Delta Modulation

Two high performance, sigma-delta audio DACs convert the digital data into two analogue signals

(left and right). These can then be mixed with analogue signals from the LINEINL, LINEINR and

MONOIN pins, and the mix is fed to the output drivers, LOUT1/ROUT1, LOUT2/ROUT2, MONOOUT

and OUT3.

•

LOUT1/ROUT1: can drive 16

Ω or 32Ω stereo headphones or stereo line output.

•

LOUT2/ROUT2: can drive an 8

Ω mono speaker, stereo headphones or a stereo line-out.

•

MONOOUT: line output designed to drive a 10k

Ω load.

•

OUT3: multi-function output, maybe used for capacitor-less headphone drive, differential

mono-out, line-out or 32

Ω earpiece driver.

WM8955 Datasheet(PDF) 15 Page - Wolfson Microelectronics plc