DIFFERENTIAL LINE INPUT .......................................................................................................................................................38
INPUT PGA GAIN CONTROL .....................................................................................................................................................39
INPUT PGA COMMON MODE AMPLIFIER ................................................................................................................................41
MICBIAS CONTROL ....................................................................................................................................................................42
Rev 4.0
3
WM8904
MICBIAS CURRENT DETECT ....................................................................................................................................................43
MICBIAS CURRENT DETECT FILTERING ................................................................................................................................43
ADC DIGITAL VOLUME CONTROL ............................................................................................................................................48
HIGH PASS FILTER ....................................................................................................................................................................50
ADC OVERSAMPLING RATIO (OSR) ........................................................................................................................................51
DYNAMIC RANGE CONTROL (DRC) ..................................................................................... 51
GAIN LIMITS ................................................................................................................................................................................53
ANTI-CLIP CONTROL .................................................................................................................................................................54
QUICK RELEASE CONTROL .....................................................................................................................................................55
GAIN SMOOTHING .....................................................................................................................................................................56
MOBILE MODE.........................................................................................................................................................58
DIGITAL MIXING ..................................................................................................................... 60
DIGITAL MIXING PATHS ............................................................................................................................................................60
DIGITAL SIDETONE ....................................................................................................................................................................62
DAC DIGITAL VOLUME CONTROL ............................................................................................................................................64
DAC SOFT MUTE AND SOFT UN-MUTE ...................................................................................................................................66
DAC OVERSAMPLING RATIO (OSR) ........................................................................................................................................68
OUTPUT SIGNAL PATH ......................................................................................................... 69
OUTPUT SIGNAL PATHS ENABLE ............................................................................................................................................70
HEADPHONE / LINE OUTPUT SIGNAL PATHS ENABLE .........................................................................................................70
OUTPUT MUX CONTROL ...........................................................................................................................................................73
HEADPHONE OUTPUTS – HPOUTL AND HPOUTR .................................................................................................................76
LINE OUTPUTS – LINEOUTL AND LINEOUTR..........................................................................................................................76
EXTERNAL COMPONENTS FOR GROUND REFERENCED OUTPUTS ..................................................................................77
REFERENCE VOLTAGES AND MASTER BIAS..................................................................... 77
ANALOGUE REFERENCE AND MASTER BIAS ........................................................................................................................77
LOW POWER PLAYBACK MODE ..............................................................................................................................................79
POP SUPPRESSION CONTROL ............................................................................................ 80
DISABLED INPUT CONTROL .....................................................................................................................................................80
DC SERVO .............................................................................................................................. 82
DC SERVO ENABLE AND START-UP .......................................................................................................................................82
DC SERVO ACTIVE MODES ......................................................................................................................................................85
DC SERVO READBACK .............................................................................................................................................................87
DIGITAL AUDIO INTERFACE ................................................................................................. 87
MASTER AND SLAVE MODE OPERATION ...............................................................................................................................87
OPERATION WITH TDM .............................................................................................................................................................88
BCLK FREQUENCY ....................................................................................................................................................................89
AUDIO DATA FORMATS (NORMAL MODE) ..............................................................................................................................89
4
Rev 4.0
WM8904
AUDIO DATA FORMATS (TDM MODE)......................................................................................................................................91
DIGITAL AUDIO INTERFACE CONTROL............................................................................... 93
BCLK AND LRCLK CONTROL ....................................................................................................................................................94
DIGITAL PULL-UP AND PULL-DOWN ........................................................................................................................................97
CLOCKING AND SAMPLE RATES ......................................................................................... 98
SYSCLK CONTROL ..................................................................................................................................................................100
CONTROL INTERFACE CLOCKING ........................................................................................................................................100
ADC / DAC CLOCK CONTROL .................................................................................................................................................102
OPCLK CONTROL ....................................................................................................................................................................102
TOCLK CONTROL ....................................................................................................................................................................103
ADC / DAC OPERATION AT 88.2K / 96K .................................................................................................................................103
FREQUENCY LOCKED LOOP (FLL) .................................................................................... 104
GPIO OUTPUTS FROM FLL .....................................................................................................................................................109
EXAMPLE FLL CALCULATION.................................................................................................................................................110
EXAMPLE FLL SETTINGS ........................................................................................................................................................111
GENERAL PURPOSE INPUT/OUTPUT (GPIO) ................................................................... 112
USING IN1L AND IN1R AS INTERRUPT INPUTS ....................................................................................................................119
CONTROL INTERFACE ........................................................................................................ 120
CONTROL WRITE SEQUENCER ......................................................................................... 122
INITIATING A SEQUENCE ........................................................................................................................................................122
PROGRAMMING A SEQUENCE ..............................................................................................................................................123
FAST START-UP FROM STANDBY .........................................................................................................................................132
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