SBOS566C June   2017  – October 2018 OPA1692

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Preamplifier for 3-Wire Electret Microphones
      2.      THD + N vs Frequency (3 VRMS, 2-kΩ Load)
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin Functions: OPA1692
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information: OPA1692
    5. 6.5 Electrical Characteristics
    6. 6.6 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Distortion Reduction
      2. 7.3.2 Phase Reversal Protection
      3. 7.3.3 Electrical Overstress
    4. 7.4 Device Functional Modes
      1. 7.4.1 Operating Voltage
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Capacitive Loads
      2. 8.1.2 Noise Performance
      3. 8.1.3 Basic Noise Calculations
      4. 8.1.4 EMI Rejection
      5. 8.1.5 EMIRR +IN Test Configuration
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curves
    3. 8.3 Other Application Examples
      1. 8.3.1 Two-Wire Electret Microphone Preamplifier
      2. 8.3.2 Battery-Powered Preamplifier for Professional Microphones
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
    3. 10.3 Power Dissipation
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Development Support
        1. 11.1.1.1 TINA-TI™ (Free Software Download)
        2. 11.1.1.2 DIP Adapter EVM
        3. 11.1.1.3 Universal Operational Amplifier EVM
        4. 11.1.1.4 Smart Amplifier Speaker Characterization Board Evaluation Module
        5. 11.1.1.5 TI Precision Designs
        6. 11.1.1.6 WEBENCH Filter Designer
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Related Links
    4. 11.4 Receiving Notification of Documentation Updates
    5. 11.5 Community Resource
    6. 11.6 Trademarks
    7. 11.7 Electrostatic Discharge Caution
    8. 11.8 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

8.2.3 Application Curves

Table 3 lists the performance of the preamplifier circuit in Figure 60. The total power supply current of the circuit is a combination of the 600 µA consumed by the microphone element itself and the 650 µA power-supply current of the OPA1692. Figure 61 shows the frequency response of the circuit. Comparing the output signal level of the microphone for a 1-Pa input signal level to the A-weighted noise of the preamplifier circuit and microphone determines the SNR of the circuit. For a 1-Pa input sound level, the microphone produces a 14.13 mVRMS signal. The microphone has an SNR of 80 dB, which results in a RMS noise voltage of 1.41 µVRMS. The input-referred A-weighted noise voltage of the preamplifier circuit is 600.6 nVRMS. The microphone and preamplifier noise must be combined as a root sum of squares, which results in a total RMS noise voltage of 1.53 µVRMS and a total circuit SNR of 79.3 dB. By selecting the OPA1692 for this design, this circuit achieves a high level of performance with low power consumption.

Table 3. Comparison of Design Requirements and Results

SPECIFICATION DESIGN REQUIREMENT DESIGN RESULT
Gain 12 V/V or 21.6 dB (120 dB Maximum Input SPL) 11.79 V/V or 21.43 dB
–3-dB bandwidth 20 Hz to 20 kHz 24 Hz to 21 kHz
Signal-to-noise ratio > 75 dB 79.3 dB
Power supply current (microphone and amplifier circuit) < 1.5 mA 1.25 mA
OPA1692 AI_C001_SBOS566.pngFigure 61. Frequency Response of the Low-Noise Preamplifier for 3-Wire Electret Microphones