OPA376-Q1_15 Datasheet, PDF (12/20 Pages) Texas Instruments – Low-Noise, Low Quiescent Current, Precision Operational Amplifier e-trim™ Series

OPA376-Q1
OPA2376-Q1, OPA4376-Q1
SBOS549 – APRIL 2011
bias current for the package is specified in the
absence of light. Depending on the amount of light
exposure in a given application, an increase in bias
current, and possible increases in offset voltage
should be expected. Fluorescent lighting may
introduce noise or hum because of the time-varying
light output. Best layout practices include end-product
packaging that provides shielding from possible light
sources during operation.
DRIVING AN ANALOG-TO-DIGITAL
CONVERTER
The low noise and wide gain bandwidth of the
OPA376-Q1 family make it an ideal driver for ADCs.
Figure 27 illustrates the OPA376-Q1 driving an
ADS8327, 16-bit, 250kSPS converter. The amplifier is
connected as a unity-gain, noninverting buffer.
+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
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PHANTOM-POWERED MICROPHONE
The circuit shown 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-Q1 serves as a single-ended input to a
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
blocks the different dc voltage levels from each other
on each end of the cable.
NOTE: (1) Suggested value; may require adjustment based on
specific application.
Figure 27. Driving an ADS8327
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