Product Preview
WM8510
DEVICE DESCRIPTION
INTRODUCTION
The WM8510 is a low power audio codec combining a high quality mono audio DAC and ADC, with
flexible line and microphone input and output processing. Applications for this device are anticipated
to include VoIP telephones, digital telephones, conference speaker phones and mobile hands-free
kits.
FEATURES
The chip offers great flexibility in use, and so can support many different modes of operation as
follows:
MICROPHONE INPUTS
Two microphone inputs are provided, MICP/MICN and MIC2, allowing for either a pseudo-differential
microphone input or a single ended microphone to be connected. These inputs have a user
programmable gain range of -12dB to +35.25dB using internal resistors. After the input PGA stage
comes a boost stage which can add a further +20dB of gain. A microphone bias is output from the
chip which can be used to bias the 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.
FLEXIBLE MIC2 INPUT
The flexible configuration of the mono input, MIC2, with integrated on-chip resistors allows several
analogue signals to be summed into the single input if required. This can be used as a microphone,
line input or an input for warning tones (beep) etc. The output from this circuit can be summed into
the mono output and/or the speaker output paths, so allowing for mixing of audio with ‘backing music’
etc as required.
SIDETONE ATTENUATION
A bypass path allows analog signals to travel directly to the outputs without passing through the ADC
and DAC. For side tone features in telephone handsets this analog bypass can be attenuated.
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 mono ADC uses a multi-bit high-order oversampling architecture to deliver optimum
performance with low power consumption. Various sample rates are supported, from the 8ks/s rate
typically used in voice dictation, up to the 48ks/s rate used in high quality audio applications.
HI-FI DAC
The hi-fi DAC provides high quality audio playback suitable for all portable mono audio type
applications.
DIGITAL FILTERING
Advanced Sigma Delta Converters are used along with digital decimation and interpolation filters to
give high quality audio at sample rates from 8ks/s to 48ks/s.
Application specific digital filters are also available which help to reduce the effect of specific noise
sources such as ‘wind noise’. The filters include a programmable ADC high pass filter and a
programmable ADC notch filter.
OUTPUT MIXING AND VOLUME ADJUST
Flexible mixing is provided on the outputs of the device; a mixer is provided for the speaker outputs,
and an additional mono summer for the mono output. These mixers allow the output of the DAC, the
output of the ADC volume control and the MIC2 input to be combined. The output volume can be
adjusted using the integrated digital volume control and there is additional analogue gain adjustment
capability on the speaker output.
w
PP Rev 1.2 December 2004
13
WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
