SLVSGP3A May   2023  – February 2024 TPS54KB20

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1  Internal VCC LDO and Using External Bias On the VCC Pin
      2. 6.3.2  Enable
      3. 6.3.3  Adjustable Soft Start
      4. 6.3.4  Power Good
      5. 6.3.5  Output Voltage Setting
      6. 6.3.6  Remote Sense
      7. 6.3.7  D-CAP4 Control
      8. 6.3.8  Multifunction Select (MSEL) Pin
      9. 6.3.9  Low-side MOSFET Zero-Crossing
      10. 6.3.10 Current Sense and Positive Overcurrent Protection
      11. 6.3.11 Low-side MOSFET Negative Current Limit
      12. 6.3.12 Overvoltage and Undervoltage Protection
      13. 6.3.13 Output Voltage Discharge
      14. 6.3.14 UVLO Protection
      15. 6.3.15 Thermal Shutdown
    4. 6.4 Device Functional Modes
      1. 6.4.1 Auto-Skip Eco-mode Light Load Operation
      2. 6.4.2 Forced Continuous-Conduction Mode
      3. 6.4.3 Powering the Device From a Single Bus
      4. 6.4.4 Powering the Device From a Split-rail Configuration
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
        1. 7.2.2.1  Output Voltage Setting Point
        2. 7.2.2.2  Choose the Switching Frequency and the Operation Mode
        3. 7.2.2.3  Choose the Inductor
        4. 7.2.2.4  Set the Current Limit (ILIM)
        5. 7.2.2.5  Choose the Output Capacitor
        6. 7.2.2.6  RAMP Selection
        7. 7.2.2.7  Choose the Input Capacitors (CIN)
        8. 7.2.2.8  Soft-Start Capacitor (SS Pin)
        9. 7.2.2.9  EN Pin Resistor Divider
        10. 7.2.2.10 VCC Bypass Capacitor
        11. 7.2.2.11 BOOT Capacitor
        12. 7.2.2.12 RC Snubber
        13. 7.2.2.13 PG Pullup Resistor
      3. 7.2.3 Application Curves
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
      2. 7.4.2 Layout Example
  9. 8 Device and Documentation Support
    1. 8.1 Documentation Support
      1. 8.1.1 Related Documentation
    2. 8.2 Receiving Notification of Documentation Updates
    3. 8.3 Support Resources
    4. 8.4 Trademarks
    5. 8.5 Electrostatic Discharge Caution
    6. 8.6 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

Package Options

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

7.4.1 Layout Guidelines

Before beginning a design using the device, consider the following:

  • Make VIN, PGND, and SW traces as wide as possible to reduce trace impedance and improve heat dissipation.
  • Place the power components (including input and output capacitors, the inductor, and the IC) on the top side of the PCB. To shield and isolate the small signal traces from noisy power lines, insert at least one solid ground inner plane.
  • Make note that placement of the VIN decoupling capacitors are important for the power MOSFET robustness. A 1μF/25V/0402 ceramic high-frequency bypass capacitor on each VIN pin (pin 3 and 9) is required, connected to the adjacent PGND pins (pin 4 and 8 respectively). 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.
  • Place eight vias below the PGND pins (pins 4, 8, and 16) and as many vias as possible near the PGND pins (pin 4 and 8). This action minimizes parasitic impedance and also lowers thermal resistance.
  • Use vias near both VIN pins and provide a low impedance connection between them through an internal layer. A via can also be placed below each of the VIN pins.
  • Place the VCC decoupling capacitor as close as possible to the device, with a short return to PGND pin 8. Make sure the VCC decoupling loop is small and use traces with a width of 12 mil or wider to route the connection.
  • Place the BOOT capacitor as close as possible to the BOOT and SW pins. Use traces with a width of 12 mil or wider to route the connection.
  • Make the switch node as short and wide as possible. The PCB trace, which connects the SW pin and high-voltage side of the inductor, is defined as switch node.
  • Always place the feedback resistors near the device to minimize the FB trace distance, no matter single-end sensing or remote sensing.
    • For remote sensing, the connections from the FB voltage divider resistors to the remote location must be a differential pair of PCB traces, and must implement Kelvin sensing across a bypass capacitor of 0.1μF or higher. The ground connection of the remote sensing signal must be connected to GOSNS pin. The VOUT connection of the remote sensing signal must be connected to the feedback resistor divider with the bottom feedback resistor terminated to the GOSNS pin. To maintain stable output voltage and minimize the ripple, the pair of remote sensing lines must stay away from any noise sources such as inductor and SW nodes, or high frequency clock lines. TI recommends to shield the pair of remote sensing lines with ground planes above and below.
    • For single-end sensing, connect the top feedback resistor between the FB pin and the output voltage to a high-frequency local output bypass capacitor of 0.1μF or higher, and short GOSNS to AGND with a short trace.
  • Connect the AGND pin (pin 2) to the PGND pad (pin 16) beneath the device.
  • Return the MSEL resistor, ILIM resistor, and SS capacitor to a quiet AGND island.
  • Avoid routing the PG signal and any other noisy signals in the application near noise sensitive signals, such as ILIM, FB and GOSNS to limit coupling.
  • See Layout Example for the layout recommendation.