CS4297A
CS4297A
data in its Slot 2. Write operations are similar, with
the register index in Slot 1 and the write data in Slot
2 of a SDATA_OUT frame. The function of each
input and output frame is detailed in Section 3,
AC Link Frame Definition. Individual register de-
scriptions are found in Section 4, Register Inter-
face.
2.4
Input Mux
The input multiplexer controls which analog input
is sent to the ADCs. The output of the input mux is
converted to stereo 18-bit digital PCM data and
sent to the controller by means of the AC-link
SDATA_IN signal.
2.5
The CS4297A volume registers control analog in-
The CS4297A has two output mixers, illustrated in put levels to the input mixer and analog output lev-
Volume Control
2.3
Output Mixer
Figure 8. The stereo output mixer sums together
the analog inputs to the CS4297A, including the
PC_BEEP and PHONE signals, according to the
settings in the volume control registers. The stereo
output mix is sent to the LINE_OUT and
ALT_LINE_OUT pins on the CS4297A. The
mono output mixer generates a monophonic sum of
the left and right channels from the stereo input
mixer. The mono output mix is sent to the
MONO_OUT output pin on the CS4297A.
els, including the master volume level, and the
alternate volume level. The PC_BEEP volume con-
trol uses 3 dB steps with a range of 0 dB to -45 dB
attenuation. All other analog volume controls use
1.5 dB steps. The analog inputs have a mixing
range of +12 dB signal gain to -34.5 dB signal at-
tenuation. The analog output volume controls have
from 0 dB to -94.5 dB attenuation for LINE_OUT
and from 0 dB to -46.5 dB attenuation for
ALT_LINE_OUT and MONO_OUT.
DS318PP6
11
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CIRRUS [ CIRRUS LOGIC ]
