SLVS510E July   2006  – March 2015

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Typical Application Circuit
  5. 5 Revision History
  6. 6 Device Comparison Table
  7. 7 Pin Configuration and Functions
  8. 8 Specifications
    1. 8.1 Absolute Maximum Ratings
    2. 8.2 ESD Ratings
    3. 8.3 Recommended Operating Conditions
    4. 8.4 Thermal Information
    5. 8.5 Electrical Characteristics
    6. 8.6 Typical Characteristics
      1. 8.6.1 Table of Graphs
  9. 9 Parameter Measurement Information
  10. 10Detailed Description
    1. 10.1 Overview
    2. 10.2 Functional Block Diagram
    3. 10.3 Feature Description
      1. 10.3.1 Controller Circuit
        1. 10.3.1.1 Synchronous Rectifier
        2. 10.3.1.2 Device Enable
        3. 10.3.1.3 Undervoltage Lockout
        4. 10.3.1.4 Soft Start and Short-Circuit Protection
    4. 10.4 Device Functional Modes
      1. 10.4.1 Power-Save Mode
  11. 11Application and Implementation
    1. 11.1 Application Information
    2. 11.2 Typical Application
      1. 11.2.1 Design Requirements
      2. 11.2.2 Detailed Design Procedure
        1. 11.2.2.1 Programming the Output Voltage
        2. 11.2.2.2 Inductor Selection
        3. 11.2.2.3 Capacitor Selection
          1. 11.2.2.3.1 Input Capacitor
          2. 11.2.2.3.2 Output Capacitor
        4. 11.2.2.4 Small Signal Stability
      3. 11.2.3 Application Curves
    3. 11.3 System Examples
  12. 12Power Supply Recommendations
  13. 13Layout
    1. 13.1 Layout Guidelines
    2. 13.2 Layout Example
    3. 13.3 Thermal Considerations
  14. 14Device and Documentation Support
    1. 14.1 Device Support
      1. 14.1.1 Third-Party Products Disclaimer
    2. 14.2 Related Links
    3. 14.3 Trademarks
    4. 14.4 Electrostatic Discharge Caution
    5. 14.5 Glossary
  15. 15Mechanical, Packaging, and Orderable Information

13 Layout

13.1 Layout Guidelines

As for all switching power supplies, the layout is an important step in the design, especially at high-peak currents and high switching frequencies. If the layout is not carefully done, the regulator could show stability problems as well as EMI problems. Therefore, use wide and short traces for the main current path and for the power ground tracks. The input capacitor, output capacitor, and the inductor should be placed as close as possible to the IC. Use a common ground node for power ground and a different one for control ground to minimize the effects of ground noise. Connect these ground nodes at any place close to the ground pin of the IC.

The feedback divider should be placed as close as possible to the ground pin of the IC. To lay out the control ground, it is recommended to use short traces as well, separated from the power ground traces. This avoids ground shift problems, which can occur due to superimposition of power ground current and control ground current.

13.2 Layout Example

TPS61070 TPS61071 TPS61072 TPS61073 Layout.gifFigure 30. PCB Layout

13.3 Thermal Considerations

Implementation of integrated circuits in low-profile and fine-pitch surface-mount packages typically requires special attention to power dissipation. Many system-dependent issues such as thermal coupling, airflow, added heat sinks and convection surfaces, and the presence of other heat-generating components affect the power-dissipation limits of a given component.

Three basic approaches for enhancing thermal performance follow.

  • Improving the power dissipation capability of the PCB design
  • Improving the thermal coupling of the component to the PCB
  • Introducing airflow in the system

The maximum recommended junction temperature (TJ) of the TPS6107x devices is 125°C. The thermal resistance of the 6-pin thin SOT package (DDC) is RΘJA = 139.1°C/W. Specified regulator operation is assured to a maximum ambient temperature TA of 85°C. Therefore, the maximum power dissipation is about 288 mW. More power can be dissipated if the maximum ambient temperature of the application is lower.

Equation 8. TPS61070 TPS61071 TPS61072 TPS61073 q_pdmax_lvs510.gif