SBOSAA7 September   2025 OPA598

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 Current Limit
      2. 6.3.2 Overcurrent Flag
      3. 6.3.3 Overtemperature Flag
      4. 6.3.4 Enable and Disable
      5. 6.3.5 Mux-Friendly Inputs
    4. 6.4 Device Functional Modes
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Application
      1. 7.2.1 High Voltage 2:1 Multiplexer With Unity Gain
        1. 7.2.1.1 Design Requirements
        2. 7.2.1.2 Detailed Design Procedure
      2. 7.2.2 Output Driver
        1. 7.2.2.1 Design Requirements
        2. 7.2.2.2 Detailed Design Procedure
        3. 7.2.2.3 Application Curve
      3. 7.2.3 Parallel Op Amps
      4. 7.2.4 Composite Amplifier
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
        1. 7.4.1.1 Thermal Considerations
      2. 7.4.2 Layout Example
  9. 8 Device and Documentation Support
    1. 8.1 Device Support
      1. 8.1.1 Development Support
        1. 8.1.1.1 PSpice® for TI
        2. 8.1.1.2 TINA-TI™ Simulation Software (Free Download)
        3. 8.1.1.3 TI Precision Designs
    2. 8.2 Documentation Support
      1. 8.2.1 Related Documentation
    3. 8.3 Receiving Notification of Documentation Updates
    4. 8.4 Support Resources
    5. 8.5 Trademarks
    6. 8.6 Electrostatic Discharge Caution
    7. 8.7 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

Package Options

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

6.3.1 Current Limit

The OPA598 current limit is set through the ILIMIT pin and is programmable from ±100mA to ±250mA, typical. The device is specified and tested for current limits of ±100mA, and ±250mA. A resistor can be used to limit the current to a fixed value, or a digital-to-analog converter (DAC) can be used to vary the current limit during operation. Figure 6-2 shows a simplified diagram of the current-limit mirror configurations, as well as common resistor or DAC settings and the respective output current limit.

OPA598 OPA598 Internal Current Limit Architecture Figure 6-2 OPA598 Internal Current Limit Architecture

The most common configuration is to set the current limit using a resistor (RCL) connected between the ILIMIT pin and the negative supply (V–). With this configuration, Equation 1 and Equation 2 are used to calculate the current limit based on the external resistor value or the resistor needed given the desired current limit value, respectively.

Equation 1. I L I M I T = 3.687 V   ×   4000 44 k Ω   +   R C L
Equation 2. R C L =   3.687 V   ×   4000 I L I M I T – 44 k Ω

An alternative to fixing the current limit to a single value using an external resistor is to use a source measure unit (SMU) or digital-to-analog converter (DAC), which enables a variable current limit.

CAUTION: With this configuration, the output of the SMU or DAC must not exceed the ILIMIT specification in Absolute Maximum Ratings to avoid reverse biasing the internal current limit circuitry and potentially damaging the device.

Use Equation 3 to set the current limit when a DAC is used (VLIMIT = DAC output voltage):

Equation 3. V L I M I T =   3.687 V – I L I M I T   ×   44 k Ω 4000

Be aware that the SMU or DAC output voltage must be referenced to the negative supply of the OPA598. Several nominal current-limit values along with the respective external resistor values and DAC output voltages are listed in Table 6-1.

Table 6-1 Nominal Current-Limit Values
CURRENT LIMIT, ILIMIT(mA) RESISTOR, RCL (kΩ) STANDARD RESISTOR VALUE, RCL (kΩ) DAC VOLTAGE, VLIMIT (V)
50 250.9 249 3.14
100 103.5 105 2.59
200 29.7 30.1 1.49
250 14.9 14.7 0.937

While the current limit tolerance of the OPA598 is specified for specific current limit levels, any resistor, SMU, or DAC inaccuracies add to the listed tolerance. To achieve the desired system level accuracy, take care when selecting these external components.