JAJSIC3D October   1997  – December 2019 OPA548

PRODUCTION DATA.  

  1. 1 特長
  2. 2 アプリケーション
    1.     概略回路図
  3. 3 概要
  4. 4 改訂履歴
  5. 5 Pin Configuration and Functions
    1.     Pin 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 Adjustable Current Limit
      2. 7.3.2 Enable/Status (E/S) Pin
      3. 7.3.3 Thermal Shutdown Status
    4. 7.4 Device Functional Modes
      1. 7.4.1 Output Disable
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Basic Circuit Connections
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Power Supply Requirements
          2. 8.2.1.2.2 Gain Setting and Input Configuration
          3. 8.2.1.2.3 Current Limit
          4. 8.2.1.2.4 Safe-Operating-Area
          5. 8.2.1.2.5 Heat Sinking
        3. 8.2.1.3 Application Curve
      2. 8.2.2 Monitoring Single- and Dual-Supplies
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
          1. 8.2.2.2.1 Output Disable and Thermal Shutdown Status
      3. 8.2.3 Programmable Power Supply
    3. 8.3 System Examples
  9. 9 Power Supply Recommendations
    1. 9.1 Output Stage Compensation
    2. 9.2 Output Protection
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Safe Operating Area
      2. 10.1.2 Amplifier Mounting
      3. 10.1.3 Power Dissipation
      4. 10.1.4 Thermal Considerations
      5. 10.1.5 Heat Sinking
        1. 10.1.5.1 Heat Sink Selection Example
    2. 10.2 Layout Example
  11. 11デバイスおよびドキュメントのサポート
    1. 11.1 デバイス・サポート
      1. 11.1.1 デベロッパー・ネットワークの製品に関する免責事項
    2. 11.2 ドキュメントのサポート
      1. 11.2.1 関連資料
    3. 11.3 ドキュメントの更新通知を受け取る方法
    4. 11.4 サポート・リソース
    5. 11.5 商標
    6. 11.6 静電気放電に関する注意事項
    7. 11.7 Glossary
  12. 12メカニカル、パッケージ、および注文情報

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

10.1.5.1 Heat Sink Selection Example

A TO-220 package is dissipating 5 W. The maximum expected ambient temperature is 40°C. Find the proper heat sink to keep the junction temperature less than 125°C (150°C minus 25°C safety margin).

Combining Equation 2 and Equation 3 gives:

Equation 3. TJ = TA + PD(RθJC + RθCH + RθHA)

TJ, TA, and PD are given. RθJC is provided in the specification table, 2.5°C/W (DC). RθCH can be obtained from the heat sink manufacturer. Its value depends on heat sink size, area, and material used. Semiconductor package type, mounting screw torque, insulating material used (if any), and thermal joint compound used (if any) also affect RθCH. A typical RθCH for a TO-220 mounted package is 1°C/W. Now we can solve for RθHA:

Equation 4. OPA548 Eq5_theta_sbos070.gif

To maintain junction temperature less than 125°C, the heat sink selected must have a RθHA less than 14°C/W. In other words, the heat sink temperature rise above ambient must be less than 67.5°C (13.5°C/W × 5 W). For example, at 5-W Thermalloy model number 6030B has a heat sink temperature rise of 66°C more than ambient (RθHA = 66°C / 5 W = 13.2°C / W), which is less than the 67.5°C required in this example. Figure 44 shows power dissipation versus ambient temperature for a TO-220 package with a 6030B heat sink.

Another variable to consider is natural convection versus forced convection air flow. Forced-air cooling by a small fan can lower RθJCA (RθCH + RθHA) dramatically. Heat sink manufactures provide thermal data for both of these cases. For additional information on determining heat sink requirements, consult Application Bulletin SBOA021.

As mentioned earlier, once a heat sink has been selected, the complete design should be tested under worst-case load and signal conditions to maintain proper thermal protection.