OPA1678 Datasheet, PDF (25/41 Pages) Texas Instruments – Low-Distortion Audio Operational Amplifiers

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OPA1678, OPA1679
SBOS855 – FEBRUARY 2017
Other Applications (continued)
8.1.3 Composite Headphone Amplifier
Figure 40 shows the BUF634 buffer inside the feedback loop of the OPA1678 to increase the available output
current for low-impedance headphones. If the BUF634 is used in wide-bandwidth mode, no additional
components beyond the feedback resistors are required to maintain loop stability.
12 V
Input
R1 ^{100 k}
0.1 F
½
+ OPA1678
±
0.1 F
RBW
100 F
0.1 F
BUF634
0.1 F
100 F
Output
-12 V
R2
R3
200
200
Copyright © 2017, Texas Instruments Incorporated
Figure 40. Composite Headphone Amplifier (Single-Channel Shown)
8.1.4 Differential Line Receiver With AC-Coupled Outputs
Figure 41 shows the OPA1678 used as an integrator which drives the reference pin of the INA1650, forcing the
output DC voltage to 0 V. This configuration is an alternative to large AC-coupling capacitors which may distort at
high output levels. The low input bias current and low input offset voltage of the OPA1678 make the device
especially well-suited for integrator applications.
Copyright © 2017, Texas Instruments Incorporated
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