WM8918 w Ultra Low Power DAC for Portable Audio Applications DESCRIPTION FEATURES 3.8mW quiescent power consumption for DAC to The WM8918 is a high performance ultra-low power stereo headphone playback DAC optimised for portable audio applications. DAC SNR 96dB typical, THD -86dB typical The device features stereo ground-referenced headphone amplifiers using the Wolfson Class-W amplifier techniques - 2.4mW quiescent power consumption for analogue bypass incorporating an innovative dual-mode charge pump playback architecture - to optimise efficiency and power consumption during playback. The ground-referenced headphone and line outputs eliminate AC coupling capacitors, and both outputs Control write sequencer for pop minimised start-up and include common mode feedback paths to reject ground shutdown noise. Single register write for default start-up sequence Control sequences for audio path setup can be pre-loaded and executed by an integrated control write sequencer to Integrated FLL provides all necessary clocks reduce software driver development and minimise pops and - Self-clocking modes allow processor to sleep clicks via Wolfsons SilentSwitch technology. - 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 Stereo digital microphone input line inputs may be connected. The input impedance is 3 single ended inputs per stereo channel constant with PGA gain setting. 1 fully differential mic / line input per stereo channel A stereo digital microphone interface is provided, with a choice of two inputs. The analogue or digital microphone Digital Dynamic Range Controller (compressor / limiter) inputs can be mixed into the headphone or line output paths. Digital sidetone mixing A dynamic range controller provides compression and level control to support a wide range of portable recording Ground-referenced headphone driver applications in conjunction with the digital microphone Ground-referenced line outputs interface. Anti-clip and quick release features offer good performance in the presence of loud impulsive noises. 32-pin QFN package (4x4mm, 0.4mm pitch) TM ReTune Mobile 5-band parametric equaliser with fully programmable coefficients is integrated for optimization of speaker characteristics. Programmable dynamic range APPLICATIONS control is also available for maximizing loudness, protecting speakers from clipping and preventing premature shutdown Wireless headsets due to battery droop. Portable multimedia players Common audio sampling frequencies are supported from a Handheld gaming 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. WOLFSON MICROELECTRONICS plc Production Data, January 2012, Rev 4.1 To receive regular email updates, sign up at 100nF 20 100nF 20 100nF 20 2.2F 100nF 20 2.2F 2.2F CPVDD CPCB CPCA CPGND DAC R DAC L BYPASS R BYPASS L IRQ / GPIO1 MCLK DGND DBVDD 100nF DCVDD 100nF AIFRXDAT LRCLK AIFTXDAT BCLK / GPIO4 SDA SCLK AGND AVDD 4.7F VMIDC 4.7F 100nF 4.7F WM8918 Production Data BLOCK DIAGRAM WM8918 M HPOUTL U IN1L/DMICDAT1 M X U PGA IN2L HPOUTFB X 1F M DYNAMIC RANGE HPOUTR U CONTROLLER DAC (DRC) X Ground-referenced 5-BAND Class-W EQUALISER CLASS-W GROUND- DIGITAL MIC REFERENCED OUTPUTS DIGITAL MONO INTERFACE MIX DIGITAL SIDE M TONE MIXING LINEOUTL U DAC X DIGITAL VOLUME CONTROL LINEOUTFB IN1R/DMICDAT2 M M U PGA LINEOUTR IN2R U X X 1F CPVOUTN AUDIO FLL / MICBIAS VMID CONTROL ADAPTIVE INTERFACE CLOCK Reference INTERFACE CHARGE PUMP CPVOUTP TDM SUPPORT CIRCUITRY MICVDD 2.2F PD, Rev 4.1, January 2012 w 2 DECIMATION FILTERS INTERPOLATION FILTERS