Product Preview
WM8955L
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:
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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.
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LOUT1/ROUT1: can drive 16Ω or 32Ω stereo headphones or stereo line output.
LOUT2/ROUT2: can drive an 8Ω mono speaker, stereo headphones or a stereo line-out.
MONOOUT: line output designed to drive a 10kΩ load.
OUT3: multi-function output, maybe used for capacitor-less headphone drive, differential
mono-out, line-out or 32Ω earpiece driver.
Product Preview Rev 0.4 May2003
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
