JAJSJT8C May   2020  – June 2021 TPS543620


  1. 特長
  2. アプリケーション
  3. 概要
  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 Typical Characteristics
  7. Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  VIN Pins and VIN UVLO
      2. 7.3.2  Enable and Adjustable UVLO
      3. 7.3.3  Adjusting the Output Voltage
      4. 7.3.4  Switching Frequency Selection
      5. 7.3.5  Switching Frequency Synchronization to an External Clock
        1. Internal PWM Oscillator Frequency
        2. Loss of Synchronization
        3. Interfacing the SYNC/FSEL Pin
      6. 7.3.6  Ramp Amplitude Selection
      7. 7.3.7  Soft Start and Prebiased Output Start-up
      8. 7.3.8  Mode Pin
      9. 7.3.9  Power Good (PGOOD)
      10. 7.3.10 Current Protection
        1. Positive Inductor Current Protection
        2. Negative Inductor Current Protection
      11. 7.3.11 Output Overvoltage and Undervoltage Protection
      12. 7.3.12 Overtemperature Protection
      13. 7.3.13 Output Voltage Discharge
      14. 7.3.14 Low-Side MOSFET Resistance Scaling
    4. 7.4 Device Functional Modes
      1. 7.4.1 Forced Continuous-Conduction Mode
      2. 7.4.2 Discontinuous Conduction Mode during Soft Start
  8. Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 1.0-V Output, 1-MHz Application
        1. Design Requirements
        2. Detailed Design Procedure
          1.  Switching Frequency
          2.  Output Inductor Selection
          3.  Output Capacitor
          4.  Input Capacitor
          5.  Adjustable Undervoltage Lockout
          6.  Output Voltage Resistors Selection
          7.  Bootstrap Capacitor Selection
          8.  BP5 Capacitor Selection
          9.  PGOOD Pullup Resistor
          10. Current Limit Selection
          11. Soft-Start Time Selection
          12. Ramp Selection and Control Loop Stability
          13. MODE Pin
        3. Application Curves
      2. 8.2.2 1.0-V Output, 1.5-MHz Application
        1. Design Requirements
        2. Detailed Design Procedure
        3. Application Curves
      3. 8.2.3 3.3-V Output, 1.0-MHz Application
        1. Design Requirements
        2. Detailed Design Procedure
        3. Application Curves
      4. 8.2.4 1.8-V Output, 1.0-MHz Typical Application
        1. Design Requirements
        2. Detailed Design Procedure
      5. 8.2.5 5.0-V Output, 1.0-MHz Typical Application
        1. Design Requirements
        2. Detailed Design Procedure
  9. Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
      1. 10.2.1 Thermal Performance
  11. 11Device and Documentation Support
    1. 11.1 Receiving Notification of Documentation Updates
    2. 11.2 サポート・リソース
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information



Layout Guidelines

Layout is a critical portion of good power supply design. See Figure 10-1 for a PCB layout example. Key guidelines to follow for the layout are:

  • VIN, PGND, and SW traces must be as wide as possible to reduce trace impedance and improve heat dissipation.
  • Place a 10-nF to 100-nF capacitor from each VIN to PGND pin and place them as close as possible to the device on the same side of the PCB. Place the remaining ceramic input capacitance next to these high frequency bypass capacitors. The remaining input capacitance can be placed on the other side of the board but use as many vias as possible to minimize impedance between the capacitors and the pins of the IC.
  • Use multiple vias near the PGND pins and use the layer directly below the device to connect them together. This helps to minimize noise and can help heat dissipation.
  • Use vias near both VIN pins and provide a low impedance connection between them through an internal layer.
  • Place the inductor as close as possible to the device to minimize the length of the SW node routing.
  • Place the BOOT-SW capacitor as close as possible to the BOOT and SW pins.
  • Place the BP5 capacitor as close as possible to the BP5 and AGND pins.
  • Place the bottom resistor in the FB divider as close as possible to the FB and AGND pins of the IC. Also keep the upper feedback resistor and the feedforward capacitor near the IC. Connect the FB divider to the output voltage at the desired point of regulation.
  • Use multiple vias in the AGND island to connect it back to internal PGND layers. Do not place these vias between the BP5 capacitor and the AGND pin. These vias will conduct switching currents between the BP5 capacitor and PGND. Placing the vias near the AGND pin can add noise to the FB divider.
  • Return the FSEL and MODE resistors to a quiet AGND island.