WM8904
Pre-Production
MICBIAS CURRENT DETECT ...................................................................................................................................... 43
MICBIAS CURRENT DETECT FILTERING .................................................................................................................. 44
MICROPHONE HOOK SWITCH DETECTION.............................................................................................................. 46
DIGITAL MICROPHONE INTERFACE.......................................................................... 47
ANALOGUE-TO-DIGITAL CONVERTER (ADC)........................................................... 49
ADC DIGITAL VOLUME CONTROL.............................................................................................................................. 49
HIGH PASS FILTER...................................................................................................................................................... 51
ADC OVERSAMPLING RATIO (OSR) .......................................................................................................................... 52
DYNAMIC RANGE CONTROL (DRC)........................................................................... 53
COMPRESSION/LIMITING CAPABILITIES .................................................................................................................. 53
GAIN LIMITS.................................................................................................................................................................. 55
DYNAMIC CHARACTERISTICS ................................................................................................................................... 55
ANTI-CLIP CONTROL................................................................................................................................................... 56
QUICK RELEASE CONTROL ....................................................................................................................................... 57
GAIN SMOOTHING....................................................................................................................................................... 57
INITIALISATION ............................................................................................................................................................ 58
RETUNETM MOBILE PARAMETRIC EQUALIZER (EQ)................................................ 59
DEFAULT MODE (5-BAND PARAMETRIC EQ) ........................................................................................................... 59
RETUNETM MOBILE MODE........................................................................................................................................... 60
EQ FILTER CHARACTERISTICS ................................................................................................................................. 60
DIGITAL MIXING........................................................................................................... 62
DIGITAL MIXING PATHS .............................................................................................................................................. 62
DAC INTERFACE VOLUME BOOST ............................................................................................................................ 64
DIGITAL SIDETONE...................................................................................................................................................... 64
DIGITAL-TO-ANALOGUE CONVERTER (DAC)........................................................... 66
DAC DIGITAL VOLUME CONTROL.............................................................................................................................. 66
DAC SOFT MUTE AND SOFT UN-MUTE..................................................................................................................... 68
DAC MONO MIX............................................................................................................................................................ 69
DAC DE-EMPHASIS...................................................................................................................................................... 69
DAC SLOPING STOPBAND FILTER ............................................................................................................................ 70
DAC OVERSAMPLING RATIO (OSR) .......................................................................................................................... 70
OUTPUT SIGNAL PATH ............................................................................................... 71
OUTPUT SIGNAL PATHS ENABLE.............................................................................................................................. 72
HEADPHONE / LINE OUTPUT SIGNAL PATHS ENABLE........................................................................................... 72
OUTPUT MUX CONTROL............................................................................................................................................. 76
OUTPUT VOLUME CONTROL...................................................................................................................................... 76
ANALOGUE OUTPUTS................................................................................................. 79
HEADPHONE OUTPUTS – HPOUTL AND HPOUTR................................................................................................... 79
LINE OUTPUTS – LINEOUTL AND LINEOUTR............................................................................................................ 79
EXTERNAL COMPONENTS FOR GROUND REFERENCED OUTPUTS.................................................................... 80
REFERENCE VOLTAGES AND MASTER BIAS........................................................... 81
ANALOGUE REFERENCE AND MASTER BIAS.......................................................................................................... 81
LOW POWER PLAYBACK MODE ................................................................................................................................ 82
POP SUPPRESSION CONTROL.................................................................................. 83
DISABLED INPUT CONTROL....................................................................................................................................... 83
CHARGE PUMP............................................................................................................ 84
DC SERVO.................................................................................................................... 85
DC SERVO ENABLE AND START-UP ......................................................................................................................... 85
DC SERVO ACTIVE MODES........................................................................................................................................ 88
DC SERVO READBACK ............................................................................................................................................... 90
DIGITAL AUDIO INTERFACE....................................................................................... 90
MASTER AND SLAVE MODE OPERATION................................................................................................................. 91
OPERATION WITH TDM............................................................................................................................................... 91
BCLK FREQUENCY...................................................................................................................................................... 92
PP, Rev 3.3, September 2012
w
4
WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
