SBOS070D October   1997  – December 2019 OPA548

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
    1.     Simplified Schematic
  3. 3 Description
  4. 4 Revision History
  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. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Receiving Notification of Documentation Updates
    4. 11.4 Support Resources
    5. 11.5 Trademarks
    6. 11.6 Electrostatic Discharge Caution
    7. 11.7 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

10.1.5 Heat Sinking

Most applications require a heat sink to assure that the maximum operating junction temperature (125°C) is not exceeded. In addition, the junction temperature should be kept as low as possible for increased reliability. Junction temperature can be determined according to the equation:

Equation 2. TJ = TA + PDRθJA

where

  • RθJA = RθJC + RθCH + RθHA
  • TJ = Junction Temperature (°C)
  • TA = Ambient Temperature (°C)
  • PD = Power Dissipated (W)
  • RθJC = Junction-to-Case Thermal Resistance (°C/W)
  • RθCH = Case-to-Heat Sink Thermal Resistance (°C/W)
  • RθHA = Heat Sink-to-Ambient Thermal Resistance (°C/W)
  • RθJA = Junction-to-Air Thermal Resistance (°C/W)

Figure 44 shows maximum power dissipation versus ambient temperature with and without the use of a heat sink. Using a heat sink significantly increases the maximum power dissipation at a given ambient temperature as shown.

The difficulty in selecting the heat sink required lies in determining the power dissipated by the OPA548. For DC output into a purely resistive load, power dissipation is simply the load current times the voltage developed across the conducting output transistor, PD = IL(VS–VO). Other loads are not as simple. Consult Application Bulletin SBOA022 for further insight on calculating power dissipation. Once power dissipation for an application is known, the proper heat sink can be selected.

OPA548 maxpowerdis1.gifFigure 44. Maximum Power Dissipation vs Ambient Temperature