FS
_
ADC
*
AOSR
)
7
(
Delay
t
pl
=
)
t
t
(
OUT
_
ADC
_
LEFT
)
t
(
COMP
_
PHASE
_
ADC
_
LEFT
pl
-
=
(
)
FS
_
ADC
*
AOSR
k
*
AOSR
*
)
5
:
6
(
Delay
)
0
:
4
(
Delay
t
f
pr
+
=
)
t
t
(
OUT
_
ADC
_
RIGHT
)
t
(
COMP
_
PHASE
_
ADC
_
RIGHT
pr
-
=
Digital Microphone Input/Decimation Filter
2.3.3.2
Special Functions
2.3.3.2.1 Microphone Bias
The TLV320DAC3203 has a built-in low noise Microphone Bias support for electret-condenser
microphones. The Bias amplifier can support up to 3mA of load current to support multiple microphones.
The Bias amplifier has been designed to provide a combination of high PSRR, low noise and
programmable bias voltages to allow the user to fine tune the biasing to specific microphone
combinations. To support a wide range of bias voltages, the bias amplifier can work of either a low analog
supply or high LDOIN supply.
Table 2-12. MICBIAS Voltage Control
Page 1, Reg 51, D(5:4)
Page 1, Reg 10, D(6)
Page 1, Reg 51, D(3)
MICBIAS Voltage (without load)
00
0
X
1.25V
00
1
X
1.0V
01
0
X
1.7V
01
1
X
1.4V
10
0
1
2.5V
10
1
1
2.1V
11
X
0
AVdd
11
X
1
LDOIN
2.3.3.2.2 Channel-to-Channel Phase Adjustment
The TLV320DAC3203 has a built-in feature to fine-adjust the phase between the stereo ADC record
signals. The phase compensation is particularly helpful to adjust delays when using dual microphones for
noise cancellation etc.
This delay can be controlled in fine amounts in the following fashion.
Delay(7:0) = Page 0/Register 85/D(7:0)
Where
(5)
where
(6)
Where k
f
is a function of the decimation filter:
Decimation Filter Type
k
f
A
0.25
B
0.5
C
1
and
(7)
Where
(8)
33
SLAU434 – May 2012
TLV320DAC3203 Application
Copyright © 2012, Texas Instruments Incorporated
