SBOS855E January   2017  – December 2022 OPA1677 , OPA1678 , OPA1679

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  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: OPA1677
    5. 6.5 Thermal Information: OPA1678
    6. 6.6 Thermal Information: OPA1679
    7. 6.7 Electrical Characteristics
    8. 6.8 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 Phase Reversal Protection
      2. 7.3.2 Electrical Overstress
      3. 7.3.3 EMI Rejection Ratio (EMIRR)
        1. 7.3.3.1 EMIRR IN+ Test Configuration
    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. 8.2 Typical Applications
      1. 8.2.1 Phantom-Powered Preamplifier for Piezo Contact Microphones
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Power Supply
          2. 8.2.1.2.2 Input Network
          3. 8.2.1.2.3 Gain
          4. 8.2.1.2.4 Output Network
        3. 8.2.1.3 Application Curves
      2. 8.2.2 Phono Preamplifier for Moving Magnet Cartridges
      3. 8.2.3 Single-Supply Electret Microphone Preamplifier
      4. 8.2.4 Composite Headphone Amplifier
      5. 8.2.5 Differential Line Receiver With AC-Coupled Outputs
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
        1. 8.4.1.1 Power Dissipation
      2. 8.4.2 Layout Example
  9. 9 Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 Development Support
        1. 9.1.1.1 PSpice® for TI
        2. 9.1.1.2 TINA-TI™ Simulation Software (Free Download)
        3. 9.1.1.3 DIP-Adapter-EVM
        4. 9.1.1.4 DIYAMP-EVM
        5. 9.1.1.5 TI Reference Designs
        6. 9.1.1.6 Filter Design Tool
    2. 9.2 Documentation Support
      1. 9.2.1 Related Documentation
    3. 9.3 Receiving Notification of Documentation Updates
    4. 9.4 Support Resources
    5. 9.5 Trademarks
    6. 9.6 Electrostatic Discharge Caution
    7. 9.7 Glossary
  10. 10Mechanical, Packaging, and Orderable Information

Package Options

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

8.2.1 Phantom-Powered Preamplifier for Piezo Contact Microphones

Contact microphones are useful for amplifying the sound of musical instruments that do not contain electric pickups, such as acoustic guitars and violins. Most contact microphones use a piezo element to convert vibrations in the body of the musical instrument to a voltage which can be amplified or recorded. The low noise and low input bias current of the OPA1678 make the device an excellent choice for high impedance preamplifiers for piezo elements. This preamplifier circuit provides high input impedance for the piezo element but has low output impedance for driving long cable runs. The circuit is also designed to be powered from 48-V phantom power which is commonly available in professional microphone preamplifiers and recording consoles.

A TINA-TI™ simulation schematic of the circuit below is available in the Tools and Software section of the OPA1678 or OPA1679 product folder.

GUID-842FA283-B5D8-47F1-B244-A61D9FAA1A30-low.gif Figure 8-1 Phantom-Powered Preamplifier for Piezo Contact Microphones