SBOS426D November   2008  – October 2016 OPA209 , OPA2209 , OPA4209

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: OPA209
    5. 6.5 Thermal Information: OPA2209
    6. 6.6 Thermal Information: OPA4209
    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 Operating Voltage
      2. 7.3.2 Input Protection
      3. 7.3.3 Noise Performance
      4. 7.3.4 Basic Noise Calculations
      5. 7.3.5 Electrical Overstress
    4. 7.4 Device Functional Modes
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curve
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  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 TI Precision Designs
        5. 11.1.1.5 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 Resources
    6. 11.6 Trademarks
    7. 11.7 Electrostatic Discharge Caution
    8. 11.8 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

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8 Application and Implementation

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

The OPAx209 are unity-gain stable, precision operational amplifiers with very low noise. Applications with noisy or high-impedance power supplies require decoupling capacitors close to the device pins. In most cases, 0.1-µF capacitors are adequate.

8.2 Typical Application

OPA209 OPA2209 OPA4209 typ_app_lpf_sbos426.png Figure 35. Low-Pass Filter

8.2.1 Design Requirements

Low-pass filters are commonly employed in signal processing applications to reduce noise and prevent aliasing. The OPAx209 are ideally suited to construct high-speed, high-precision active filters. Figure 35 shows a second-order, low-pass filter commonly encountered in signal processing applications.

Use the following parameters for this design example:

  • Gain = 5 V/V (inverting gain)
  • Low-pass cutoff frequency = 25 kHz
  • Second-order Chebyshev filter response with 3-dB gain peaking in the passband

8.2.2 Detailed Design Procedure

The infinite-gain multiple-feedback circuit for a low-pass network function is shown in Figure 35. Use Equation 1 to calculate the voltage transfer function.

Equation 1. OPA209 OPA2209 OPA4209 App_EQ_1_SBOS426.gif

This circuit produces a signal inversion. For this circuit, the gain at DC and the low-pass cutoff frequency are calculated by Equation 2:

Equation 2. OPA209 OPA2209 OPA4209 App_EQ_2_SBOS426.gif

8.2.3 Application Curve

OPA209 OPA2209 OPA4209 App Graph_SBOS426.png Figure 36. OPAx209 Second-Order, 25-kHz, Chebyshev, Low-Pass Filter