JAJSRJ1A June   2011  – February 2024 OPA564-Q1

PRODUCTION DATA  

  1.   1
  2. 1 特長
  3. 2 アプリケーション
  4. 3 概要
  5. 4 Device Comparison Table
  6. 5 Pin Configuration and Functions
  7. 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
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Adjustable Current Limit
        1. 7.3.1.1 Setting the Current Limit
      2. 7.3.2 Enable and Shutdown (E/S) Pin
      3. 7.3.3 Input Protection
      4. 7.3.4 Output Shutdown
      5. 7.3.5 Microcontroller Compatibility
      6. 7.3.6 Current Limit Flag
      7. 7.3.7 Thermal Protection
      8. 7.3.8 Junction Temperature Measurement Using TSENSE
    4. 7.4 Device Functional Modes
  9. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Basic Configuration
      2. 8.1.2 Output-Stage Compensation
      3. 8.1.3 Output Protection
      4. 8.1.4 Power Dissipation and Safe Operating Area
    2. 8.2 Typical Applications
      1. 8.2.1 Improved Howland Current Pump
      2. 8.2.2 Programmable Power Supply
      3. 8.2.3 Powerline Communication
      4. 8.2.4 Motor-Drive Circuit
      5. 8.2.5 DC Motor-Speed Controller (Without Tachometer)
      6. 8.2.6 Generating VDIG
      7. 8.2.7 Temperature Measurement
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
        1. 8.4.1.1 Thermally Enhanced PowerPAD™ Integrated Circuit Package
          1. 8.4.1.1.1 Bottom-Side Thermal Pad Assembly Process
  10. 9 Device and Documentation Support
    1. 9.1 ドキュメントの更新通知を受け取る方法
    2. 9.2 サポート・リソース
    3. 9.3 Trademarks
    4. 9.4 静電気放電に関する注意事項
    5. 9.5 用語集
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

パッケージ・オプション

メカニカル・データ（パッケージ｜ピン）
サーマルパッド・メカニカル・データ
発注情報

7.3.1 Adjustable Current Limit

The OPA564-Q1 provides overcurrent protection to the load through an accurate, user-adjustable current limit (ISET pin). The current limit value, ILIM, can be set from 0.4A to 1.6A by controlling the current through the ISET pin. Setting the current limit does not require special power resistors. The output current does not flow through the ISET pin.

A simple resistor to the negative rail is sufficient for a general, coarse limit of the output current. Figure 6-30 exhibits the percent of error in the transfer function between ISET and IOUT versus the current limit set resistor, RSET. The ±3 sigma distribution is derived from one lot of material characterized at room temperature. As significant variation can occur from unit to unit and across operating conditions, do not use the adjustable current limit to set an exact output current, but rather, to protect the device. Figure 6-31 and Figure 6-32 show how this error translates to variation in IOUT versus RSET. The dotted line represents the ideal output current setting that is determined by the following equation:

Equation 1. I L I M ≅ 20 k × 1.2 V 5 k Ω + R S E T

The mismatch errors between the current-limit set mirror and the output stage are primarily a result of variations in the approximately 1.2V band-gap reference, an internal 5kΩ resistor, the mismatch between the current limit and the output stage mirror, and the tolerance and temperature coefficient of the RSET resistor referenced to the negative rail. Additionally, an increase in junction temperature can induce added mismatch in accuracy between the ISET and IOUT mirror. See Figure 8-7 for a method that can be used to dynamically change the current limit setting using a simple, zero-drift current source. This approach simplifies the current-limit equation to the following:

Equation 2. I L I M ≅ 20 k × I S E T

The current into the ISET pin is determined by the NPN current source. Therefore, the errors contributed by the internal 1.2V band-gap reference and the 5kΩ resistor mismatch are eliminated, thus improving the overall accuracy of the transfer function. In this case, the primary source of error in ISET is the RSET resistor tolerance and the beta of the NPN transistor.

The primary intent of the current limit on the OPA564-Q1 is coarse protection of the output stage; therefore, exercise caution when attempting to control the output current by dynamically toggling the current-limit setting. Predictable performance is better achieved by controlling the output voltage through the feedback loop of the OPA564-Q1.