PCM3793A
PCM3794A
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SLAS529A–JANUARY 2007–REVISED FEBRUARY 2007
Register 81
B15
0
B14
B13
B12
B11
B10
B9
B8
B7
B6
B5
B4
B3
B2
B1
B0
RFM0
Register 81
IDX6
IDX5
IDX4
IDX3
IDX2
IDX1
IDX0
HPF1
HPF0
RMUL
RMUR
RSV
DSMC
RFM1
IDX[6:0]: 101 0001b (51h): Register 81
HPF[1:0]: High-Pass Filter Selection
Default value: 00
The PCM3793A/94A 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]
0 0
High-Pass Filter Selection
fC = 4 Hz at 48 kHz (default)
fC = 240 Hz at 48 kHz
0 1
1 0
fC = 120 Hz at 48 kHz
1 1
High-pass filter disabled
RMUL: Digital Soft Mute Control for L-Channel ADC
RMUR: Digital Soft Mute Control for R-Channel ADC
Default value: 1
The digital output of the ADC can be independently muted by setting RMUL and RMUR = 1. The digital data is
changed from the current attenuation level to mute level by a 1-dB step for every 8/fS time period. When PMUL
and PMUR are set to 0, the digital data is changed from the mute level to the current attenuation level by a 1-dB
step for every 8/fS time period. In the PCM3793A/94A, audible zipper noise can be reduced by selecting
zero-cross detection (register 86, ZCRS).
RMUL, RMUR = 0
RMUL, RMUR = 1
Mute disabled
Mute enabled (default)
DSMC: Waiting Time for ADC Mute Off at Power Up
Default value: 0
The ADC digital output has an optional delay after power up when DSMC = 0. It is recommended to set
DSMC = 0.
DSMC = 0
DSMC = 1
10 ms at 48 kHz (default)
No delay
RFM[1:0]: Audio Interface Selection for ADC (Digital Output)
Default value: 00
The audio interface for the ADC digital input supports I2S, right-justified, left-justified, and DSP formats.
RFM [1:0]
0 0
Audio Interface Selection for ADC Digital Output
I2S format (default)
0 1
Right-justified format
1 0
Left-justified format
1 1
DSP format
42
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