WM8918 Datasheet, PDF (1/176 Pages) Cirrus Logic – Ultra Low Power DAC for Portable Audio Applications

w
WM8918
Ultra Low Power DAC for Portable Audio Applications
DESCRIPTION
The WM8918 is a high performance ultra-low power stereo
DAC optimised for portable audio applications.
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.
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.
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.
A stereo digital microphone interface is provided, with a
choice of two inputs. The analogue or digital microphone
inputs can be mixed into the headphone or line output paths.
A dynamic range controller provides compression and level
control to support a wide range of portable recording
applications in conjunction with the digital microphone
interface. Anti-clip and quick release features offer good
performance in the presence of loud impulsive noises.
ReTune^TM 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.
Common audio sampling frequencies are supported from a
wide range of external clocks, either directly or generated
via the FLL.
The WM8918 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.
FEATURES
 3.8mW quiescent power consumption for DAC to
headphone playback
 DAC SNR 96dB typical, THD -86dB typical
 2.4mW quiescent power consumption for analogue bypass
playback
 Control write sequencer for pop minimised start-up and
shutdown
 Single register write for default start-up sequence
 Integrated FLL provides all necessary clocks
- Self-clocking modes allow processor to sleep
- All standard sample rates from 8kHz to 96kHz
 Stereo digital microphone input
 3 single ended inputs per stereo channel
 1 fully differential mic / line input per stereo channel
 Digital Dynamic Range Controller (compressor / limiter)
 Digital sidetone mixing
 Ground-referenced headphone driver
 Ground-referenced line outputs
 32-pin QFN package (4x4mm, 0.4mm pitch)
APPLICATIONS
 Wireless headsets
 Portable multimedia players
 Handheld gaming
WOLFSON MICROELECTRONICS plc
To receive regular email updates, sign up at http://www.wolfsonmicro.com/enews
Production Data, January 2012, Rev 4.1
Copyright 2012 Wolfson Microelectronics plc