ZHCSMD4C January   2022  – December 2022 OPA593

PRODUCTION DATA  

  1. 1 特性
  2. 2 应用
  3. 3 说明
  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
    5. 6.5 Electrical Characteristics
    6. 6.6 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 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. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Output Driver
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
        3. 8.2.1.3 Application Curve
      2. 8.2.2 High Voltage 2:1 Multiplexer With Unity Gain
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
        1. 8.4.1.1 Thermal Considerations
      2. 8.4.2 Layout Example
  9. 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™ 仿真软件（免费下载）
    2. 9.2 接收文档更新通知
    3. 9.3 支持资源
    4. 9.4 Trademarks
    5. 9.5 Electrostatic Discharge Caution
    6. 9.6 术语表
  10. 10Mechanical, Packaging, and Orderable Information

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7.3.1 Current Limit

The OPA593 current limit is set through the ILIMIT pin and is programmable from ±25 mA to ±250 mA, typical. The device is specified and tested for current limits of ±25 mA, ±50 mA, ±100 mA, ±250 mA. 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 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 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

Be aware that the SMU or DAC output voltage must be referenced to the negative supply of the OPA593. Several nominal current-limit values along with the respective external resistor values and DAC output voltages are listed in Table 7-1.

Table 7-1 Nominal Current-Limit Values
CURRENT LIMIT, ILIMIT(mA) RESISTOR, RCL (kΩ) DAC VOLTAGE, VLIMIT (V)(1)
25 536 3.33
50 237 2.98
100 90.9 2.27
200 16.9 0.85
250 2.29 0.14
(1) Voltages are referenced to the negative supply, V−

While the current limit tolerance of the OPA593 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. Figure 7-2 shows a correlation between the ideal or calculated output current limit and the actual current limit as measured on the OPA593.

Figure 7-2 Typical Output Current vs Current-Limit Resistor Value