SBOS525C August   2011  – June 2016 OPA2188

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Zero-Drift Amplifier Portfolio
  6. 6 Pin Configuration and 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, VS = ±4 V to ±18 V (VS = 8 V to 36 V)
    6. 7.6 Electrical Characteristics: Low-Voltage Operation, VS = ±2 V to < ±4 V (VS = +4 V to < +8 V)
    7. 7.7 Typical Characteristics: 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 EMI Rejection
      3. 8.3.3 Phase-Reversal Protection
      4. 8.3.4 Capacitive Load and Stability
      5. 8.3.5 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 Curve
    3. 9.3 System Examples
      1. 9.3.1 Discrete INA + Attenuation for ADC With 3.3-V Supply
      2. 9.3.2 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 Software Download)
        2. 12.1.1.2 DIP Adapter EVM
        3. 12.1.1.3 Universal Op Amp EVM
        4. 12.1.1.4 TI Precision Designs
        5. 12.1.1.5 WEBENCH Filter Designer
    2. 12.2 Documentation Support
      1. 12.2.1 Related Documentation
    3. 12.3 Receiving Notification of Documentation Updates
    4. 12.4 Community Resource
    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 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality.

9.1 Application Information

9.2 Typical Applications

9.2.1 High-Side Voltage-to-Current (V-I) Converter

The circuit shown in Figure 44 is a high-side voltage-to-current (V-I) converter. It translates in input voltage of 0 V to 2 V to and output current of 0 mA to 100 mA. Figure 45 shows the measured transfer function for this circuit. The low offset voltage and offset drift of the OPA2188 facilitate excellent dc accuracy for the circuit.

OPA2188 High-Side-Voltage-to-Current-Converter.gif Figure 44. High-Side Voltage-to-Current (V-I) Converter

9.2.1.1 Design Requirements

The design requirements are as follows:

  • Supply Voltage: 5 V DC
  • Input: 0 V to 2 V DC
  • Output: 0 mA to 100 mA DC

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 OPA2188 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 OPA2188 family uses 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 these devices appropriate for precise dc control. The rail-to-rail output stage of the OPA2188 ensures 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 TIPD102.

9.2.1.3 Application Curve

OPA2188 Measured-transfer-function-for-High-Side.gif Figure 45. Measured Transfer Function for High-Side V-I Converter

9.3 System Examples

9.3.1 Discrete INA + Attenuation for ADC With 3.3-V Supply

The application examples of Figure 46 and Figure 47 highlight only a few of the circuits where the OPA2188 can be used.

OPA2188 ai_ina_attn_33v_bos525.gif Figure 46. Discrete INA + Attenuation for ADC with 3.3-V Supply

9.3.2 RTD Amplifier with Linearization

OPA2188 ai_rtd_amp_bos525.gif
1.

NOINDENT:

R5 provides positive-varying excitation to linearize output.
Figure 47. RTD Amplifier with Linearization