SBOS701D December   2015  – August 2021 OPA191 , OPA2191 , OPA4191

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information: OPA191
    5. 6.5 Thermal Information: OPA2191
    6. 6.6 Thermal Information: OPA4191
    7. 6.7 Electrical Characteristics: VS = ±4 V to ±18 V (VS = 8 V to 36 V)
    8. 6.8 Electrical Characteristics: VS = ±2.25 V to ±4 V (VS = 4.5 V to 8 V)
    9. 6.9 Typical Characteristics
  7. 7 Parameter Measurement Information
    1. 7.1 Input Offset Voltage Drift
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Input Protection Circuitry
      2. 8.3.2 EMI Rejection
      3. 8.3.3 Phase Reversal Protection
      4. 8.3.4 Thermal Protection
      5. 8.3.5 Capacitive Load and Stability
      6. 8.3.6 Common-Mode Voltage Range
      7. 8.3.7 Electrical Overstress
      8. 8.3.8 Overload Recovery
    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 Low-side Current Measurement
        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 16-Bit Precision Multiplexed Data-Acquisition System
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
      3. 9.2.3 Slew Rate Limit for Input Protection
  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™ SImulation Software (Free Download)
        2. 12.1.1.2 TI Precision Designs
    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 transfer function of the circuit in Figure 9-1 is given in Equation 2

Equation 2. GUID-3C87A8C6-E2FD-47E7-AA15-84BE8CDA781B-low.gif

The load current (ILOAD) produces a voltage drop across the shunt resistor (RSHUNT). The load current is set from 0 A to 1 A. To keep the shunt voltage below 100 mV at maximum load current, the largest shunt resistor is defined using Equation 3.

Equation 3. GUID-285944B4-25C5-46F1-B8A5-FF0863DD5BFA-low.gif

Using Equation 3, RSHUNT is calculated to be 100 mΩ. The voltage drop produced by ILOAD and RSHUNT is amplified by the OPA191 to produce an output voltage of 0 V to 4.9 V. The gain needed by the OPA191 to produce the necessary output voltage is calculated using Equation 4:

Equation 4. GUID-C47EF7DF-1F9B-43B9-B7F9-86DC1A6E0F82-low.gif

Using Equation 4, the required gain is calculated to be 49 V/V, which is set with resistors RF and RG. Equation 5 is used to size the resistors, RF and RG, to set the gain of the OPA191 to 49 V/V.

Equation 5. GUID-D0779A2C-B3D1-495C-9699-CFC25BBC60E0-low.gif

Choosing RF as 360 kΩ, RG is calculated to be 7.5 kΩ. RF and RG were chosen as 360 kΩ and 7.5 kΩ because they are standard value resistors that create a 49:1 ratio. Other resistors that create a 49:1 ratio can also be used. Figure 2 shows the measured transfer function of the circuit shown in Figure 9-1.