SBOS642C March   2013  – January 2020 OPA188

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Auto-Zero Technology Provides Ultra-Low Temperature Drift
  4. 4 Revision History
  5. 5 Device Comparison Table
    1. 5.1 Portfolio Comparison
  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: High-Voltage Operation
    6. 7.6 Electrical Characteristics: Low-Voltage Operation
    7. 7.7 Typical Characteristics: Table of Graphs
      1. 7.7.1 Table of Graphs
    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 Characteristics
      2. 8.3.2 Phase-Reversal Protection
      3. 8.3.3 Input Bias Current Clock Feedthrough
      4. 8.3.4 Internal Offset Correction
      5. 8.3.5 EMI Rejection
      6. 8.3.6 Capacitive Load and Stability
      7. 8.3.7 Electrical Overstress
    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 High-Side Voltage-to-Current (V-I) Converter
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
        3. 9.2.1.3 Application Curves
      2. 9.2.2 Discrete INA + Attenuation for ADC With 3.3-V Supply
      3. 9.2.3 Bridge Amplifier
      4. 9.2.4 Low-Side Current Monitor
      5. 9.2.5 Programmable Power Supply
      6. 9.2.6 RTD Amplifier With Linearization
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Development Support
        1. 12.1.1.1 TINA-TI (Free Download Software)
    2. 12.2 Documentation Support
      1. 12.2.1 Related Documentation
    3. 12.3 Receiving Notification of Documentation Updates
    4. 12.4 Support Resources
    5. 12.5 Trademarks
    6. 12.6 Electrostatic Discharge Caution
    7. 12.7 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

9.2.1.2 Detailed Design Procedure

The V-I transfer function of the circuit is based on the relationship between the input voltage, VIN, and the three current sensing resistors, RS1, RS2, and RS3. The relationship between VIN and RS1 determines the current that flows through the first stage of the design. The current gain from the first stage to the second stage is based on the relationship between RS2 and RS3.

For a successful design, pay close attention to the dc characteristics of the operational amplifier chosen for the application. To meet the performance goals, this application benefits from an operational amplifier with low offset voltage, low temperature drift, and rail-to-rail output. The OPA188 CMOS operational amplifier is a high-precision, ultra-low offset, ultra-low drift amplifier, optimized for low-voltage, single-supply operation, with an output swing to within 15 mV of the positive rail. The devices in the OPA188 family use chopping techniques to provide low initial offset voltage and near-zero drift over time and temperature. Low offset voltage and low drift reduce the offset error in the system, making this device appropriate for precise dc control. The rail-to-rail output stage of the OPA188 makes sure that the output swing of the operational amplifier is able to fully control the gate of the MOSFET devices within the supply rails.

A detailed error analysis, design procedure, and additional measured results are given in reference design TIPD102, a step-by-step process to design a High-Side Voltage-to-Current (V-I) Converter.

For step-by-step design procedure, circuit schematics, bill of materials, PCB files, simulation results, and test results, refer to Precision Design Guide TIPD102, High-Side Voltage-to-Current (V-I) Converter.