SBOS195E March   2001  – April 2018 OPA2355 , OPA3355 , OPA355

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified Schematic
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
    1.     Pin Functions: OPA355
    2.     Pin Functions: OPA2355
    3.     Pin Functions: OPA3355
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information: OPA355
    5. 7.5 Thermal Information: OPA2355
    6. 7.6 Thermal Information: OPA3355
    7. 7.7 Electrical Characteristics: VS = 2.7 V to 5.5 V (Single-Supply)
    8. 7.8 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Operating Voltage
      2. 8.3.2 Enable Function
      3. 8.3.3 Output Drive
    4. 8.4 Device Functional Modes
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 Transimpedance Amplifier
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
          1. 9.2.1.2.1 Optimizing The Transimpedance Circuit
        3. 9.2.1.3 Application Curve
      2. 9.2.2 High-Impedance Sensor Interface
      3. 9.2.3 Driving ADCs
      4. 9.2.4 Active Filter
    3. 9.3 Video
    4. 9.4 Wideband Video Multiplexing
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Related Links
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Community Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

9.2.2 High-Impedance Sensor Interface

Many sensors have high source impedances that may range up to 10 MΩ, or even higher. The output signal of sensors often must be amplified or otherwise conditioned by an amplifier. The input bias current of this amplifier loads the sensor output and causes a voltage drop across the source resistance, Figure 34 shows (V(+INx) = VS – I(BIAS) × R(S).)The last term (I(BIAS) × R(S)) shows the voltage drop across R(S). To prevent errors introduced to the system as a result of this voltage, use an op amp with low input bias current with high-impedance sensors. This low current keeps the I(BIAS) × R(S) error contribution less than the input voltage noise of the amplifier so that input voltage noise is not the dominant noise factor. The OPAx355 op amps feature low input bias current (typically 200 fA), and as a result, a preferred choice for these applications.

OPA355 OPA2355 OPA3355 ai_noise_ibias_sbos492.gifFigure 34. Noise as a Result of I(BIAS)