WM8904
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Ultra Low Power CODEC for Portable Audio Applications
DESCRIPTION
FEATURES
3.0mW quiescent power consumption for DAC to
headphone playback
The WM8904 is a high performance ultra-low power stereo
CODEC optimised for portable audio applications.
DAC SNR 96dB typical, THD -86dB typical
ADC SNR 91dB typical, THD -80dB typical
The device features stereo ground-referenced headphone
amplifiers using the Wolfson ‘Class-W’ amplifier techniques -
incorporating an innovative dual-mode charge pump
architecture - to optimise efficiency and power consumption
during playback. The ground-referenced headphone and line
outputs eliminate AC coupling capacitors, and both outputs
include common mode feedback paths to reject ground
noise.
2.4mW quiescent power consumption for analogue bypass
playback
Control write sequencer for pop minimised start-up and
shutdown
Control sequences for audio path setup can be pre-loaded
and executed by an integrated control write sequencer to
reduce software driver development and minimise pops and
clicks via Wolfson’s SilentSwitch™ technology.
Single register write for default start-up sequence
Integrated FLL provides all necessary clocks
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Self-clocking modes allow processor to sleep
All standard sample rates from 8kHz to 96kHz
The analogue input stage can be configured for single
ended or differential inputs. Up to 3 stereo microphone or
line inputs may be connected. The input impedance is
constant with PGA gain setting.
Stereo digital microphone input
3 single ended inputs per stereo channel
1 fully differential mic / line input per stereo channel
A stereo digital microphone interface is provided, with a
choice of two inputs.
Digital Dynamic Range Controller (compressor / limiter)
Digital sidetone mixing
A dynamic range controller provides compression and level
control to support a wide range of portable recording
applications. Anti-clip and quick release features offer good
performance in the presence of loud impulsive noises.
Ground-referenced headphone driver
Ground-referenced line outputs
ReTuneTM Mobile 5-band parametric equaliser with fully
programmable coefficients is integrated for optimization of
speaker characteristics. Programmable dynamic range
control is also available for maximizing loudness, protecting
speakers from clipping and preventing premature shutdown
due to battery droop.
32-pin QFN package (4 x 4mm, 0.4mm pitch)
36-ball WLCSP package (2.6 x 2.5mm, 6 x 6 ball grid,
0.4mm pitch)
Common audio sampling frequencies are supported from a
wide range of external clocks, either directly or generated
via the FLL.
APPLICATIONS
Portable multimedia players
Multimedia handsets
Handheld gaming
The WM8904 can operate directly from a single 1.8V
switched supply. For optimal power consumption, the digital
core can be operated from a 1.0V supply.
Wireless headsets
Mobile internet devices
Netbooks
WOLFSON MICROELECTRONICS plc
Pre-Production, September 2012, Rev 3.3
Copyright 2012 Wolfson Microelectronics plc
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