SBOS955 February   2019 OPA2356-EP

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified Schematic
  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
    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 Operating Voltage
      2. 7.3.2 Output Drive
    4. 7.4 Device Functional Modes
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Transimpedance Amplifier
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Custom Design With WEBENCH® Tools
          2. 8.2.1.2.2 OPA2356-EP Design Procedure
            1. 8.2.1.2.2.1 Optimizing the Transimpedance Circuit
        3. 8.2.1.3 Application Curve
      2. 8.2.2 High-Impedance Sensor Interface
      3. 8.2.3 Driving ADCs
      4. 8.2.4 Active Filter
  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 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Community Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

8.2.4 Active Filter

The OPA2356-EP is designed for active filter applications that require a wide bandwidth, fast slew rate, low-noise, single-supply operational amplifier. Figure 35 depicts a 500-kHz, second-order, low-pass filter using the multiple-feedback (MFB) topology. The components are selected to provide a maximally-flat Butterworth response. Beyond the cutoff frequency, roll-off is –40 dB/dec. The Butterworth response is preferred for applications requiring predictable gain characteristics, such as the anti-aliasing filter used in front of an ADC.

One point to observe when considering the MFB filter is that the output is inverted, relative to the input. If this inversion is not required, or not desired, a noninverting output can be achieved through one of the following options:

  1. Adding an inverting amplifier,
  2. Adding an additional second-order MFB stage,
  3. Using a noninverting filter topology, such as the Sallen-Key (see Figure 36).

MFB and Sallen-Key, low-pass and high-pass filter synthesis is quickly accomplished using TI’s FilterPro™ program. This software is available as a free download at www.ti.com.

OPA2356-EP ai_2order_lopass_filt_sbos492.gifFigure 35. Second-Order Butterworth 500-kHz Low-Pass Filter
OPA2356-EP ai_sallen_key_sbos492.gifFigure 36. OPA2356-EP Configured as a Three-Pole, 20-kHz, Sallen-Key Filter