SBVS020C September   2000  – February 2020 REF200

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Functional Block Diagram
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Electrical Characteristics
    5. 6.5 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Temperature Drift
    4. 7.4 Device Functional Modes
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Lead Resistance Cancelation (3-Wire RTD)
      3. 8.2.3 Application Curves
    3. 8.3 System Examples
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Support Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

8.2.2.1 Lead Resistance Cancelation (3-Wire RTD)

Figure 14 shows the 3-wire RTD configuration can be used to cancel lead resistance. The resistance in each lead must be equal to cancel the error. Also, the two current sources in the REF200 must be equal. Notice that the voltage developed on the two top leads of the RTD are equal and opposite polarity so that the amplifiers input is only from the RTD voltage. In this example, the RTD drop is 14.8 mV and the leads each have 1 mV. Notice that the 1 mV drops cancel. Finally, notice that the voltage on the 3rd lead (2 mV) creates a small shift in the common mode voltage. In some applications, a larger resistor is intentionally added to shift the common-mode voltage. However, the INA326 has a rail-to-rail common mode range, so it can accept common-mode voltages near ground.

REF200 Three_wire_RTD_config.gifFigure 14. 3-Wire RTD Configuration Cancels Lead Resistance