Datasheet

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MUTx – Soft Mute Control
OVER – Oversampling Rate Control
PCM1742
SBAS176A – DECEMBER 2000 – REVISED APRIL 2005
B15 B14 B13 B12 B11 B10 B9 B8 B7 B6 B5 B4 B3 B2 B1 B0
REGISTER 18 0 IDX6 IDX5 IDX4 IDX3 IDX2 IDX1 IDX0 RSV OVER RSV RSV RSV RSV MUT2 MUT1
where x = 1 or 2, corresponding to the DAC output V
OUT
L (x = 1) and V
OUT
R (x = 2).
Default value: 0
MUTx = 0 Mute disabled (default)
MUTx = 1 Mute enabled
The mute bits, MUT1 and MUT2, are used to enable or disable the soft mute function for the corresponding DAC
outputs, V
OUT
L and V
OUT
R. The soft mute function is incorporated into the digital attenuators. When mute is
disabled (MUTx = 0), the attenuator and DAC operate normally. When mute is enabled by setting MUTx = 1, the
digital attenuator for the corresponding output is decreased from the current setting to the infinite attenuation
setting by one attenuator step (0.5 dB) at a time for every 8/f
S
period. This provides a pop-free muting of the
DAC output.
By setting MUTx = 0, the attenuator is increased by one step for every 8/f
S
period to the previously programmed
attenuation level.
Default value: 0
System clock rate = 256 f
S
, 384 f
S
, 512 f
S
, or 768 f
S
OVER = 0 64× oversampling (default)
OVER = 1 128× oversampling
System clock rate = 128 f
S
or 192 f
S
OVER = 0 32× oversampling (default)
OVER = 1 64× oversampling
The OVER bit is used to control the oversampling rate of the delta-sigma DACs. The OVER = 1 setting is
recommended when the oversampling rate is 192 kHz (system clock is 128 f
S
or 192 f
S
).
18