Datasheet
www.ti.com
Register Map
REGISTER DEFINITIONS
ATx[7:0] – Digital Attenuation Level Setting
PCM1742
SBAS176A – DECEMBER 2000 – REVISED APRIL 2005
The mode control register map is shown in Table 3 . Each register includes an index (or address) indicated by the
IDX[6:0] bits.
Table 3. Mode Control Register Map
IDX REGIS- B15 B14 B13 B12 B11 B10 B9 B8 B7 B6 B5 B4 B3 B2 B1 B0
(B14–B8) TER
10h 16 0 IDX6 IDX5 IDX4 IDX3 IDX2 IDX1 IDX0 AT17 AT16 AT15 AT14 AT13 AT12 AT11 AT10
11h 17 0 IDX6 IDX5 IDX4 IDX3 IDX2 IDX1 IDX0 AT27 AT26 AT25 AT24 AT23 AT22 AT21 AT20
12h 18 0 IDX6 IDX5 IDX4 IDX3 IDX2 IDX1 IDX0 RSV
(1)
OVER RSV
(1)
RSV
(1)
RSV
(1)
RSV
(1)
MUT2 MUT1
13h 19 0 IDX6 IDX5 IDX4 IDX3 IDX2 IDX1 IDX0 RSV
(1)
DMF1 DMF0 DM12 RSV
(1)
RSV
(1)
DAC2 DAC1
14h 20 0 IDX6 IDX5 IDX4 IDX3 IDX2 IDX1 IDX0 RSV
(1)
RSV
(1)
FLT RSV
(1)
RSV
(1)
FMT2 FMT1 FMT0
15h 21 0 IDX6 IDX5 IDX4 IDX3 IDX2 IDX1 IDX0 RSV
(1)
RSV
(1)
RSV
(1)
RSV
(1)
RSV
(1)
RSV
(1)
RSV
(1)
RSV
(1)
16h 22 0 IDX6 IDX5 IDX4 IDX3 IDX2 IDX1 IDX0 RSV
(1)
RSV
(1)
RSV
(1)
RSV
(1)
RSV
(1)
AZRO ZREV DREV
(1) RSV: Reserved for test operation. It should be set to 0 during normal operation.
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
REGISTER 17 0 IDX6 IDX5 IDX4 IDX3 IDX2 IDX1 IDX0 AT27 AT26 AT25 AT24 AT23 AT22 AT21 AT20
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
Each DAC channel (V
OUT
L and V
OUT
R) includes a digital attenuator function. The attenuation level can be set
from 0 dB to –63 dB, in 0.5-dB steps. Changes in attenuation levels are made by incrementing or decrementing,
by one step (0.5 dB), for every 8/f
S
time interval until the programmed attenuator setting is reached. Alternatively,
the attenuation level can be set to infinite attenuation, or mute. The attenuation data for each channel can be set
individually.
The attenuation level is calculated using the following formula:
Attenuation level (dB) = 0.5 (ATx[7:0]
DEC
– 255)
where: ATx[7:0]
DEC
= 0 through 255
for: ATx[7:0]
DEC
= 0 through 128, the attenuator is set to infinite attenuation.
The following table shows attenuator levels for various settings.
ATx[7:0] DECIMAL VALUE ATTENUATOR LEVEL SETTING
1111 1111b 255 0 dB, no attenuation (default)
1111 1110b 254 –0.5 dB
1111 1101b 253 –1 dB
: : :
1000 0011b 131 –62 dB
1000 0010b 130 –62.5 dB
1000 0001b 129 –63 dB
1000 0000b 128 Mute
: : :
0000 0000b 0 Mute
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