Datasheet
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Register Definitions
PCM1780 , PCM1781 , PCM1782
SLES132B – MARCH 2005 – REVISED AUGUST 2006
B15 B14 B13 B12 B11 B10 B9 B8 B7 B6 B5 B4 B3 B2 B1 B0
REGISTER 16 0 IDX6 IDX5 IDX4 IDX3 IDX2 IDX1 IDX0 AT17 AT16 AT15 AT14 AT13 AT12 AT11 AT10
B15 B14 B13 B12 B11 B10 B9 B8 B7 B6 B5 B4 B3 B2 B1 B0
REGISTER 17 0 IDX6 IDX5 IDX4 IDX3 IDX2 IDX1 IDX0 AT27 AT26 AT25 AT24 AT23 AT22 AT21 AT20
ATx[7:0]: Digital Attenuation Level Setting
Where x = 1 or 2, corresponding to the DAC output V
OUT
L (x = 1) and V
OUT
R (x = 2)
Default value: 1111 1111b
ATx[7:0] DECIMAL VALUE ATTENUATION LEVEL SETTING
DAMS = 0 DAMS = 1
1111 1111b 255 0 dB, no attenuation (default) 0 dB, no attenuation (default)
1111 1110b 254 –0.5 dB –1 dB
1111 1101b 253 –1 dB –2 dB
: : : :
1001 1100b 156 –49.5 dB –99 dB
1001 1011b 155 –50 dB –100 dB
1001 1010b 154 –50.5 dB Mute
: : :
1000 0010b 130 –62.5 dB Mute
1000 0001b 129 –63 dB Mute
1000 0000b 128 Mute Mute
: : : :
0000 0000b 0 Mute Mute
Each DAC channel (V
OUT
L or V
OUT
R) includes a digital attenuation function. The attenuation level can be set
from 0 dB to R dB, in S-dB steps. Changes in attenuator levels are made by incrementing or decrementing by
one step (S dB) every 8/f
S
time internal until the programmed attenuator setting is reached. Alternatively, the
attenuation level can be set to infinite attenuation (or mute).
R (range) and S (step) are –63 and 0.5 for DAMS = 0 and –100 and 1 for DAMS = 1, respectively. The DAMS
bit is defined in register 21.
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 level is set to infinite attenuation (mute).
20
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