SBOS948F February   2019  – May 2021 BUF634A

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics: Wide-Bandwidth Mode
    6. 7.6 Electrical Characteristics: Low-Quiescent Current Mode
    7. 7.7 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Output Current
      2. 8.3.2 Thermal Shutdown
      3. 8.3.3 ESD Protection
    4. 8.4 Device Functional Modes
      1. 8.4.1 Adjustable Bandwidth
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 High-Frequency Applications
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
    1. 10.1 Power Dissipation and Thermal Considerations
  11. 11Layout
    1. 11.1 Layout Guidelines
      1. 11.1.1 SOIC Layout Guidelines (D Package Without a Thermal Pad)
      2. 11.1.2 HSOIC Layout Guidelines (DDA Package With a Thermal Pad)
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Third-Party Products Disclaimer
      2. 12.1.2 Development Support
        1. 12.1.2.1 TINA-TI (Free Software Download)
        2. 12.1.2.2 TI Precision Designs
    2. 12.2 Documentation Support
      1. 12.2.1 Related Documentation
    3. 12.3 Receiving Notification of Documentation Updates
    4. 12.4 Support Resources
    5. 12.5 Trademarks
    6. 12.6 Electrostatic Discharge Caution
    7. 12.7 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • D|8
  • DDA|8
  • DRB|8
Thermal pad, mechanical data (Package|Pins)
Orderable Information

10.1 Power Dissipation and Thermal Considerations

The BUF634A includes automatic thermal shutoff protection. This protection circuitry shuts down the amplifier if the junction temperature exceeds approximately 180°C. When the junction temperature decreases to approximately 160°C, the buffer turns on again. The package and the PCB dictate the thermal characteristics of the device. Maximum power dissipation for a particular package is calculated using the following formula.

Equation 1. GUID-9511A77D-BFA5-4056-A50B-3AF9836DB380-low.gif

where

  • PDmax is the maximum power dissipation in the amplifier (W).
  • Tmax is the absolute maximum junction temperature (°C).
  • TA is the ambient temperature (°C).
  • θJA = θJC + θCA
  • θJC is the thermal coefficient from the silicon junctions to the case (°C/W).
  • θCA is the thermal coefficient from the case to ambient air (°C/W).

The thermal coefficient for the thermal pad integrated circuit packages are substantially improved over the traditional SOIC package. The data for the thermal pad packages assume a board layout that follows the thermal pad package layout guidelines referenced above and detailed in the PowerPAD™ Thermally Enhanced Package application report. If the thermal package integrated circuit package is not soldered to the PCB, the thermal impedance increases substantially and may cause serious heat and performance issues.

When determining whether or not the device satisfies the maximum power dissipation requirement, make sure to consider not only quiescent power dissipation, but dynamic power dissipation. Often times, this dissipation is difficult to quantify because the signal pattern is inconsistent, but an estimate of the RMS power dissipation provides visibility into a possible problem.