OPA1692 Datasheet, PDF (12/23 Pages) Texas Instruments – Low-Power, Low-Noise and Low-Distortion Audio Operational Amplifiers

OPA1692, OPA1694
SBOS566 – JUNE 2017
8 Application and Implementation
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NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
8.1 Application Information
8.1.1 Capacitive Loads
The dynamic characteristics of the OPA169x amplifiers have been optimized for commonly encountered gains,
loads, and operating conditions. The combination of low closed-loop gain and high capacitive loads decreases
the phase margin of the amplifier and can lead to gain peaking or oscillations. As a result, heavier capacitive
loads must be isolated from the output. The simplest way to achieve this isolation is to add a small resistor (R_S
equal to 50 Ω, for example) in series with the output.
8.2 Typical Application
The low power consumption, noise and distortion of the OPA169x family of audio operational amplifiers make
them an excellent choice for a number of analog audio circuits. One such circuit is shown in Figure 10 which
illustrates a preamplifier circuit suitable for high-performance electret microphones which use a 3-wire interface.
Primo EM-173
Microphone
5V
C1
0.1 F
Microphone
Cable
R1
5.9 k
R3
100
R2
100 k
5V
0.1 F
OPA1692
+
C2
100 pF
±
0.1 F
-5 V
Output
C3
1F
R6 100
R4 100 k
R5 1.1 k
C4 6.8 nF
Copyright © 2017, Texas Instruments Incorporated
Figure 10. Low-Noise Preamplifier for 3-Wire Electret Microphones
8.2.1 Design Requirements
• Maximum Input Sound Pressure Level (SPL): 120 dB
• –3-dB Bandwidth: 20 Hz to 20 kHz
• Signal-to-Noise Ratio: > 75 dB
• Power Supply Voltage: ± 5 V
• Power Supply Current: < 1.5 mA
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