Datasheet
REGISTER DEFINITIONS
ATx[7:0]: Digital Attenuation Level Setting
PCM1680
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.................................................................................................................................................. SLES133B – MARCH 2005 – REVISED OCTOBER 2008
B15 B14 B13 B12 B11 B10 B9 B8 B7 B6 B5 B4 B3 B2 B1 B0
REGISTER 1 0 IDX6 IDX5 IDX4 IDX3 IDX2 IDX1 IDX0 AT17 AT16 AT15 AT14 AT13 AT12 AT11 AT10
REGISTER 2 0 IDX6 IDX5 IDX4 IDX3 IDX2 IDX1 IDX0 AT27 AT26 AT25 AT24 AT23 AT22 AT21 AT20
REGISTER 3 0 IDX6 IDX5 IDX4 IDX3 IDX2 IDX1 IDX0 AT37 AT36 AT35 AT34 AT33 AT32 AT31 AT30
REGISTER 4 0 IDX6 IDX5 IDX4 IDX3 IDX2 IDX1 IDX0 AT47 AT46 AT45 AT44 AT43 AT42 AT41 AT40
REGISTER 5 0 IDX6 IDX5 IDX4 IDX3 IDX2 IDX1 IDX0 AT57 AT56 AT55 AT54 AT53 AT52 AT51 AT50
REGISTER 6 0 IDX6 IDX5 IDX4 IDX3 IDX2 IDX1 IDX0 AT67 AT66 AT65 AT64 AT63 AT62 AT61 AT60
REGISTER 16 0 IDX6 IDX5 IDX4 IDX3 IDX2 IDX1 IDX0 AT77 AT76 AT75 AT74 AT73 AT72 AT711 AT70
REGISTER 17 0 IDX6 IDX5 IDX4 IDX3 IDX2 IDX1 IDX0 AT87 AT86 AT85 AT84 AT83 AT82 AT81 AT80
Where x = 1 – 8, corresponding to the DAC output V
OUT
x. Default value: 1111 1111b.
ATTENUATION LEVEL SETTING
ATx[7:0] DECIMAL VALUE 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 output, V
OUT
1 through V
OUT
8, 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).
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