Datasheet

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PCM1870
SLAS544A – MAY 2007 – REVISED SEPTEMBER 2007
Register 81
B15 B14 B13 B12 B11 B10 B9 B8 B7 B6 B5 B4 B3 B2 B1 B0
Register 81 0 IDX6 IDX5 IDX4 IDX3 IDX2 IDX1 IDX0 HPF1 HPF0 RMUL RMUR RSV DSMC RFM1 RFM0
IDX[6:0]: 101 0001b (51h) Register 81
HPF[1:0]: High-Pass Filter Selection
Default value: 00
The PCM1870 has a digital high-pass filter to remove dc voltage at the input of the ADC. The cutoff frequency of
the high-pass filter can be selected.
HPF[1:0] High Pass Filter Selection
0 0 f
C
= 4 Hz at 48 kHz (default)
0 1 f
C
= 240 Hz at 48 kHz
1 0 f
C
= 120 Hz at 48 kHz
1 1 High-pass filter disabled
RMUL: Digital Soft Mute Control for ADC L-Channel
RMUR: Digital Soft Mute Control for ADC R-Channel
Default value: 1
The digital output of the ADC can be independently muted or unmuted. The transition from the current volume
level to mute, or the return to the previous volume setting from mute, occurs at the rate of one 1-dB step for each
8/f
S
time period. When RMUL and RMUR = 0, the digital data is increased from mute to the previous attenuation
level, and when RMUL and RMUR = 1, the digital data is decreased from the current attenuation level to mute. In
the PCM1870, audible zipper noise can be reduced by using zero-cross detection (register 85, ZCRS).
RMUL, RMUR = 0 Mute disabled
RMUL, RMUR = 1 Mute enabled (default)
DSMC: Waiting Time Turn ADC Mute Off at Power Up
Default value: 0
ADC digital output has waiting time at power up when DSMC = 0. It is recommended to set DSMC = 0.
DSMC = 0 10 ms at 48 kHz (default)
DSMC = 1 No wait
RFM[1:0]: Audio Interface Selection for ADC (Digital Output)
Default value: 00
The audio interface format for ADC digital output has I
2
S, right-justified, left-justified, and DSP formats.
RFM[1:0] Audio Interface Selection for ADC Digital Output
0 0 I
2
S (default)
0 1 Right-justified
1 0 Left-justified
1 1 DSP mode
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Product Folder Link(s): PCM1870