Datasheet
H(z) +
N0 ) N1 z
*1
32768 * D1 z
*1
(1)
DIGITAL AUDIO PROCESSING FOR RECORD PATH
AudioSerialBusInterface
PGA
0/+59.5dB
0.5dBsteps
ADC
+
DAC
L
Volume
Control
DIN
DOUT
BCLK
WCLK
DINL
DINR
DOUTL
DOUTR
ADC
PGA
0/+59.5dB
0.5dBsteps
+
DACR
Volume
Control
Effects
AGC
AGC
RecordPath
RecordPath
DAC
Powered
Down
DAC
Powered
Down
Effects
SW-D1
SW-D2
SW-D3
SW-D4
LeftChannel
AnalogInputs
RightChannel
AnalogInputs
AUTOMATIC GAIN CONTROL (AGC)
TLV320AIC3107
SLOS545C – NOVEMBER 2008 – REVISED MARCH 2009 ..............................................................................................................................................
www.ti.com
Programming the Left channel is done by writing to Page 1, Registers 65-70, and the right channel is
programmed by writing to Page 1, Registers 71-76. After the coefficients have been loaded, these ADC high
pass filter coefficients can be selected by writing to Page 0, Register 107, D7-D6, and the high pass filter can be
enabled by writing to Page 0, Register 12, bits D7-D4.
In applications where record only is selected, and DAC is powered down, the playback path signal processing
blocks can be used in the ADC record path. These filtering blocks can support high pass, low pass, band pass or
notch filtering. In this mode, the record only path has switches SW-D1 through SW-D4 closed, and reroutes the
ADC output data through the digital signal processing blocks. Since the DAC ' s Digital Signal Processing blocks
are being re-used, naturally the addresses of these digital filter coefficients are the same as for the DAC digital
processing and are located on Page 1, Registers 1-52. This record only mode is enabled by powering down both
DACs by writing to Page 0, Register 37, bits D7-D6 (D7=D6= ” 0 ” ). Next, enable the digital filter pathway for the
ADC by writing a “ 1 ” to Page 0, Register 107, bit D3. (Note, this pathway is only enabled if both DACs are
powered down.) This record only path can be seen in Figure 24 .
Figure 24. Record Only Mode With Digital Processing Path Enabled
An automatic gain control (AGC) circuit is included with the ADC and can be used to maintain nominally constant
output signal amplitude when recording speech signals (it can be fully disabled if not desired). This circuitry
automatically adjusts the PGA gain as the input signal becomes loud or weak, such as when a person speaking
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