OPA376 Datasheet, PDF (12/23 Pages) Burr-Brown (TI) – Precision, Low Noise, Low Quiescent Current, Operational Amplifier

OPA376
OPA2376
OPA4376
SBOS406B – JUNE 2007 – REVISED SEPTEMBER 2007
www.ti.com
+5V
C₁
0.1mF
OPA376
(1)
R₁
100W
(1)
C₃
1.2nF
V_IN
+5V
+IN _ADS8327
Low Power
-IN
16-Bit
500kSPS
REF IN
+5V
REF5040
4.096V
C4
100nF
NOTE: (1) Suggested value; may require adjustment based on specific application.
Figure 27. Driving an ADS8327
PHANTOM-POWERED MICROPHONE
The circuit provided in Figure 28 depicts how a
remote microphone amplifier can be powered by a
phantom source on the output side of the signal
cable. The cable serves double duty, carrying both
the differential output signal from, and dc power to
the microphone amplifier stage.
An OPA2376 serves as a single-ended input, to
differential output amplifier with a 6dB gain.
Common-mode bias for the two op amps is provided
by the dc voltage developed across the electret
microphone element. A 48V phantom supply is
reduced to 5.1V by the series 6.8kΩ resistors on the
output side of the cable, and the 4.7kΩ and zener
diode on the input side of the cable. AC coupling is
used to block the different dc voltage levels from
each other on each end of the cable.
An INA163 instrumentation amplifier provides
differential inputs and receives the balanced audio
signals from the cable. The INA163 gain may be set
from 0dB to 80dB by selecting the R_G value. The
INA163 circuit is typical of the input circuitry used in
mixing consoles.
Panasonic
WM-034CY
Microphone
R₁
2.7kW
1/2
OPA2376
1kW
1kW
10kW
+
10mF
1/2
OPA2376
100W
33mF
D₁
5.1V
Phantom Power
(Provides power source for microphone)
48V
1mF
C₂
R₆
33mF 100W
C₃
R₇
33mF 100W
R₈
4.7kW
R₉
4.7kW
2
3
1
2
3
1
Low-level differential audio signal
is transmitted differentially on the
same cable as power to the microphone.
R₁₀
6.8kW
R₁₁
6.8kW
10mF
10mF
+15V
R_G
INA163
3.3kW
3.3kW
-15V
Typical microphone input circuit used in mixing consoles.
Figure 28. Phantom-Powered Electret Microphone
12
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