SLVS919C January   2009  – September 2015 TPS54060


  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Pin Configuration and Functions
  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 Timing Resistor and External Clock (RT/CLK Pin) Timing Requirements
    7. 6.7 Timing Resistor and External Clock (RT/CLK PIN) Switching Characteristics
    8. 6.8 Typical Characteristics
  7. Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Fixed Frequency PWM Control
      2. 7.3.2  Slope Compensation Output Current
      3. 7.3.3  Pulse Skip Eco-mode
      4. 7.3.4  Low Dropout Operation and Bootstrap Voltage (BOOT)
      5. 7.3.5  Error Amplifier
      6. 7.3.6  Voltage Reference
      7. 7.3.7  Slow Start/Tracking Pin (SS/TR)
      8. 7.3.8  Overload Recovery Circuit
      9. 7.3.9  Constant Switching Frequency and Timing Resistor (RT/CLK Pin)
      10. 7.3.10 Overcurrent Protection and Frequency Shift
      11. 7.3.11 Power Good (PWRGD Pin)
      12. 7.3.12 Overvoltage Transient Protection
      13. 7.3.13 Thermal Shutdown
      14. 7.3.14 Small Signal Model for Loop Response
      15. 7.3.15 Simple Small Signal Model for Peak Current Mode Control
      16. 7.3.16 Small Signal Model for Frequency Compensation
    4. 7.4 Device Functional Modes
  8. Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Adjusting the Output Voltage
      2. 8.1.2 Enable and Adjusting Undervoltage Lockout
      3. 8.1.3 Sequencing
      4. 8.1.4 Selecting the Switching Frequency
      5. 8.1.5 How to Interface to RT/CLK Pin
    2. 8.2 Typical Applications
      1. 8.2.1 Buck Converter for 3.3-V Output
        1. Design Requirements
        2. Detailed Design Procedure
          1.  Selecting the Switching Frequency
          2.  Output Inductor Selection (LO)
          3.  Output Capacitor
          4.  Catch Diode
          5.  Input Capacitor
          6.  Slow Start Capacitor
          7.  Bootstrap Capacitor Selection
          8.  Undervoltage Lockout (UVLO) Set Point
          9.  Output Voltage and Feedback Resistors Selection
          10. Compensation
          11. Discontinuous Mode and Eco Mode Boundary
          12. Power Dissipation Estimate
        3. Application Curves
      2. 8.2.2 Inverting Power Supply
      3. 8.2.3 Split Rail Power Supply
  9. Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Estimated Circuit Area
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
      2. 11.1.2 Development Support
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

10 Layout

10.1 Layout Guidelines

Layout is a critical portion of good power supply design. There are several signals paths that conduct fast changing currents or voltages that can interact with stray inductance or parasitic capacitance to generate noise or degrade the power supplies performance. To help eliminate these problems, the VIN pin should be bypassed to ground with a low ESR ceramic bypass capacitor with X5R or X7R dielectric. Care should be taken to minimize the loop area formed by the bypass capacitor connections, the VIN pin, and the anode of the catch diode. See Figure 65 for a PCB layout example. The GND pin should be tied directly to the power pad under the IC and the power pad.

The power pad should be connected to any internal PCB ground planes using multiple vias directly under the IC. The PH pin should be routed to the cathode of the catch diode and to the output inductor. Since the PH connection is the switching node, the catch diode and output inductor should be located close to the PH pins, and the area of the PCB conductor minimized to prevent excessive capacitive coupling. For operation at full rated load, the top side ground area must provide adequate heat dissipating area. The RT/CLK pin is sensitive to noise so the RT resistor should be located as close as possible to the IC and routed with minimal lengths of trace. The additional external components can be placed approximately as shown. It may be possible to obtain acceptable performance with alternate PCB layouts, however this layout has been shown to produce good results and is meant as a guideline.

10.1.1 Estimated Circuit Area

The estimated printed circuit board area for the components used in the design of Figure 50 is 0.55 in2. This area does not include test points or connectors.

10.2 Layout Example

TPS54060 layout_lvs795.gif Figure 65. PCB Layout Example