PCM1681_15 Datasheet, PDF (28/44 Pages) Texas Instruments – PCM1681 24-Bit, 192-kHz Sampling, Enhanced Multilevel Delta-Sigma,Eight-Channel Audio Digital-to-Analog Converter

PCM1681, PCM1681-Q1
SLES211C – FEBRUARY 2008 – REVISED JULY 2015
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Each DAC output, V_OUT1 through V_OUT8, has a digital attenuation function. The attenuation level can be set from
0 dB to R dB, in S-dB steps. Changes in attenuation levels are made by incrementing or decrementing by one
step (S-dB) for every 8/f_S time interval until the programmed attenuation setting is reached. Alternatively, the
attenuation level can be set to infinite attenuation (or mute). Range (R) and step (S) are –63 and 0.5,
respectively, for DAMS = 0 and –100 and 1, respectively, for DAMS = 1. The DAMS bit is defined in register 13.
The attenuation data for each channel can be set individually. The attenuation level can be calculated using the
following formula:
Attenuation level (dB) = S • (ATx[7:0]_DEC – 255)
where ATx[7:0]_DEC = 0 through 255. For ATx[7:0]_DEC = 0 through 128 with DAMS = 0 or for ATx[7:0]_DEC = 0
through 154 with DAMS = 1, the attenuation is set to infinite attenuation (mute).
B15 B14 B13 B12 B11 B10 B9 B8 B7 B6 B5 B4 B3 B2 B1 B0
REGISTER 7 0 IDX6 IDX5 IDX4 IDX3 IDX2 IDX1 IDX0 MUT8 MUT7 MUT6 MUT5 MUT4 MUT3 MUT2 MUT1
REGISTER 18 0 IDX6 IDX5 IDX4 IDX3 IDX2 IDX1 IDX0 RSV RSV RSV RSV RSV RSV MUT8 MUT7
8.6.2.2 MUTx: Soft Mute Control
where x = 1–8, corresponding to the DAC output V_OUTx. Default value: 0
MUTx
0
1
Mute disabled (default)
Mute enabled
SOFT MUTE CONTROL
The mute bits, MUT1 through MUT8, are used to enable or disable the soft mute function for the corresponding
DAC outputs, V_OUT1 through V_OUT8. MUT7 and MUT8 of register 7 and register 18 work as an OR function,
either one or both can be used according to the requirements of the application. 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 one attenuator step (S-dB) at a time. This
provides a quiet, pop-free muting of the DAC output. On returning from soft mute, by setting MUTx = 0, the
attenuator is increased one step at a time to the previously programmed attenuator level. The step size, S, is 0.5
dB for DAMS = 0 and 1 dB for DAMS = 1.
B15 B14 B13 B12 B11 B10 B9 B8 B7 B6 B5 B4 B3 B2 B1 B0
REGISTER 8 0 IDX6 IDX5 IDX4 IDX3 IDX2 IDX1 IDX0 DAC8 DAC7 DAC6 DAC5 DAC4 DAC3 DAC2 DAC1
REGISTER 19 0 IDX6 IDX5 IDX4 IDX3 IDX2 IDX1 IDX0 RSV RSV RSV RSV RSV RSV DAC8 DAC7
8.6.2.3 DACx: DAC Operation Control
where x = 1–8, corresponding to the DAC output V_OUTx. Default value: 0
DACx
0
1
DAC OPERATION CONTROL
DAC operation enabled (default)
DAC operation disabled
The DAC operation controls are used to enable and disable the DAC outputs, V_OUT1 through V_OUT8. When
DACx = 0, the output amplifier input is connected to the DAC output. When DACx = 1, the output amplifier input
is switched to the dc common voltage (V_COM), equal to V_CC/2. DAC7 and DAC8 of register 8 and register 19 work
as an OR function, either one or both can be used according to the requirements of the application.
REGISTER 9
B15 B14 B13 B12 B11 B10 B9 B8 B7 B6 B5 B4 B3
B2
B1
B0
0 IDX6 IDX5 IDX4 IDX3 IDX2 IDX1 IDX0 RSV RSV FLT RSV FMT3 FMT2 FMT1 FMT0
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