SBOS659B January   2022  – August 2022 OPA593

ADVANCE INFORMATION  

  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Pin Configuration and Functions
  6. Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Typical Characteristics
  7. Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Current Limit
      2. 7.3.2 Overcurrent Flag
      3. 7.3.3 Overtemperature Flag
      4. 7.3.4 Output Enable and Disable
      5. 7.3.5 Mux-Friendly Inputs
    4. 7.4 Device Functional Modes
  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
      3. 8.2.3 Application Curve
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
  9. Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 Development Support
        1. 9.1.1.1 PSpice® for TI
        2. 9.1.1.2 TINA-TI™ Simulation Software (Free Download)
    2. 9.2 Receiving Notification of Documentation Updates
    3. 9.3 Support Resources
    4. 9.4 Trademarks
    5. 9.5 Electrostatic Discharge Caution
    6. 9.6 Glossary
  10. 10Mechanical, Packaging, and Orderable Information

Package Options

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

Current Limit

The OPA593 has a high-accuracy, externally programmable current limit that has a ±5% tolerance for output currents ≥ 50 mA. The current limit is set through the ILIMIT pin and is programmable from 10 mA to 250 mA (typical). 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 7-1 shows a simplified diagram of the current-limit mirror configurations, as well as common resistor or DAC settings and the respective output current limit.

Figure 7-1 OPA593 Internal Current Limit Configurations

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:

Equation 1. I L I M I T =   3.687   V   ×   4000 56.7   k Ω + R C L
Equation 2. R C L =   3.687   V   ×   4000 I L I M I T   –56.7   k Ω

An alternative to fixing the current limit to a single value using an external resistor is to use a DAC, which enables a variable current limit.

CAUTION: With this configuration, the output of the DAC must not exceed the ILIMIT specification in Section 6.1 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   ×   56.7   k Ω 4000

Several nominal current limit values along with their respective external resistor values and DAC output voltages are listed in Table 7-1.

Table 7-1 Nominal Current-Limit Values
OUTPUT CURRENT LIMIT (mA) RESISTOR (kΩ) DAC VOLTAGE (V)
50 237 2.98
100 90.9 2.27
200 16.9 0.85

The current limit of the OPA593 has a ±10% tolerance for output currents between 25 mA and 50 mA, and is ±5% accurate for currents ≥ 50 mA. Any resistor or DAC tolerances add to the OPA593 tolerance, so take care when selecting the external components to make sure and provide the desired system level accuracy. Figure 7-2 shows a correlation between the ideal or calculated output current limit and the actual current limit as measured on the OPA593.

GUID-20211110-SS0I-FK92-RDPJ-JFW9SBTHBDKW-low.png Figure 7-2 Output Current vs Current-Limit Resistor Configuration