SLOS868C December   2013  – May 2018 OPA355-Q1

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison Table
    1. 5.1 Device Comparison Table
  6. 6 Pin Configuration and Functions
    1.     Pin Functions
  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
    5. 7.5 Electrical Characteristics
    6. 7.6 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
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Trademarks
    2. 12.2 Electrostatic Discharge Caution
    3. 12.3 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • DBV|6
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 means of an amplifier. The input bias current of this amplifier can load the sensor output and cause a voltage drop across the source resistance, as shown in Figure 34, where (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, an op amp with very low input bias current must be used with high impedance sensors. This low current keeps the error contribution by I(BIAS) × R(S) less than the input voltage noise of the amplifier, so that it does not become the dominant noise factor. The OPA355-Q1 op amp features very low input bias current (typically 200 fA), and is therefore a preferred choice for such applications.

OPA355-Q1 ai_noise_ibias_sbos492.gifFigure 34. Noise as a Result of I(BIAS)