SBOS629B April   2018  – May 2025 OPA858

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison Table
  6. 5 Pin Configuration and Functions
  7. 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
  8. 7 Parameter Measurement Information
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Input and ESD Protection
      2. 8.3.2 Feedback Pin
      3. 8.3.3 Wide Gain-Bandwidth Product
      4. 8.3.4 Slew Rate and Output Stage
      5. 8.3.5 Current Noise
    4. 8.4 Device Functional Modes
      1. 8.4.1 Split-Supply and Single-Supply Operation
      2. 8.4.2 Power-Down Mode
  10. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Using the OPA858 as a Transimpedance Amplifier
    2. 9.2 Typical Applications
      1. 9.2.1 TIA in an Optical Front-End System
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
        3. 9.2.1.3 Application Curves
    3. 9.3 Power Supply Recommendations
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
      2. 9.4.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Device Support
      1. 10.1.1 Development Support
    2. 10.2 Documentation Support
      1. 10.2.1 Related Documentation
    3. 10.3 Receiving Notification of Documentation Updates
    4. 10.4 Support Resources
    5. 10.5 Trademarks
    6. 10.6 Electrostatic Discharge Caution
    7. 10.7 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information

8.3.2 Feedback Pin

The OPA858 pin layout is optimized to minimize parasitic inductance and capacitance, which is a critical care about in high-speed analog design. The FB pin (pin 1) is internally connected to the output of the amplifier. The FB pin is separated from the inverting input of the amplifier (pin 3) by a no connect (NC) pin (pin 2). The NC pin must be left floating. There are two advantages to this pin layout:

  1. A feedback resistor (RF) can connect between the FB and IN– pin on the same side of the package (see Figure 8-4) rather than going around the package.
  2. The isolation created by the NC pin minimizes the capacitive coupling between the FB and IN– pins by increasing the physical separation between the pins.

OPA858 RF Connection Between FB and IN– PinsFigure 8-4 RF Connection Between FB and IN– Pins