SBOS900B September   2018  – June 2019 OPA2156

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Low Input Voltage Noise Spectral Density
      2.      OPA2156 Transimpedance Configuration
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin 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: OPA2156
    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 Phase Reversal Protection
      2. 7.3.2 Electrical Overstress
      3. 7.3.3 Thermal Considerations
      4. 7.3.4 Thermal Shutdown
      5. 7.3.5 Common-Mode Voltage Range
      6. 7.3.6 Overload Recovery
    4. 7.4 Device Functional Modes
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Slew Rate Limit for Input Protection
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Power Dissipation
    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 TI Precision Designs
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Receiving Notification of Documentation Updates
    4. 11.4 Community Resources
    5. 11.5 Trademarks
    6. 11.6 Electrostatic Discharge Caution
    7. 11.7 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

8.2.2 Detailed Design Procedure

In this example the OPA2156 serves as a transimpedance amplifier for a differential photodiode. The differential configuration allows for a wider output range (0 to 10-V differential) compared to a single-ended configuration (0 V to 5 V). This output can be connected to a differential successive approximation register (SAR) analog-to-digital converter (ADC). The basic equation for a differential transimpedance amplifier output voltage is shown in Equation 3.

Equation 3. OPA2156 Eq3-Transimpedance.gif

Equation 3 can be rearranged to calculate the value of the feedback resistors as shown in Equation 4.

Equation 4. OPA2156 Eq4-Feedback_Resistor.gif

Adding a capacitor to the feedback loop creates a filter which will remove undesired noise beyond its cutoff frequency. For this application a 1-MHz cutoff frequency was selected. The equation for an RC filter is provided in Equation 5.

Equation 5. OPA2156 Eq5-Cutoff_Frequency.gif

Rearranging this equation to solve for the capacitor value is show in Equation 6.

Equation 6. OPA2156 Eq6-Feedback_Capacitor.gif

For more information on photodiode transimpedance amplifier system design and for a single-ended example, see TIDU535: 1 MHz, Single-Supply, Photodiode Amplifier Reference Design.