Datasheet

R
5
40W
R
1
1kW
R
2
1kW
1kW
R
4
270W
R
3
270W
R
6
40W
C
2
1nF
C
1
1nF
0.1 Fm
0.1 Fm
10 Fm
V+
+8Vto+16V
-8Vto 16V-
V-
1/2
PCM1804
V
OCM
3
5
4
6
7
1
2
8
C
3
2.7nF
V
COM
(2.5V)
Enable
(1)
Balancedor
Single-Ended
Input
OPA1632
OPA134
+
10 Fm
0.1 Fm
+
+
-
OPA1632
www.ti.com SBOS286B –DECEMBER 2003–REVISED JANUARY 2010
APPLICATION INFORMATION
Figure 11 shows the OPA1632 used as a The V
COM
reference voltage output on the PCM1804
differential-output driver for the PCM1804 ADC provides the proper input common-mode
high-performance audio ADC. reference voltage (2.5V). This V
COM
voltage is
buffered with op amp A
2
and drives the output
Supply voltages of ±15V are commonly used for the
common-mode voltage pin of the OPA1632. This
OPA1632. The relatively low input voltage swing
biases the average output voltage of the OPA1632 to
required by the ADC allows use of lower
2.5V.
power-supply voltage, if desired. Power supplies as
low as ±8V can be used in this application with The signal gain of the circuit is generally set to
excellent performance. This reduces power approximately 0.25 to be compatible with
dissipation and heat rise. Power supplies should be commonly-used audio line levels. Gain can be
bypassed with 10mF tantalum capacitors in parallel adjusted, if necessary, by changing the values of R
1
with 0.1mF ceramic capacitors to avoid possible and R
2
. The feedback resistor values (R
3
and R
4
)
oscillations and instability. should be kept relatively low, as indicated, for best
noise performance.
R
5
, R
6
, and C
3
provide an input filter and charge
glitch reservoir for the ADC. The values shown are
generally satisfactory. Some adjustment of the values
may help optimize performance with different ADCs.
Figure 11. ADC Driver for Professional Audio
Copyright © 2003–2010, Texas Instruments Incorporated 7
Product Folder Link(s): OPA1632