SLUSCD4B March   2017  – May 2018 TPS543C20


  1. Features
  2. Applications
  3. Description
    1.     Device Images
      1.      Simplified Schematic
  4. Revision History
  5. Device Comparison Table
  6. Pin Configuration and Functions
    1.     Pin Functions
  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
    6. 7.6 Typical Characteristics
  8. Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
    4. 8.4 Device Functional Modes
      1. 8.4.1  Soft-Start Operation
      2. 8.4.2  Input and VDD Undervoltage Lockout (UVLO) Protection
      3. 8.4.3  Power Good and Enable
      4. 8.4.4  Voltage Reference
      5. 8.4.5  Prebiased Output Start-up
      6. 8.4.6  Internal Ramp Generator
        1. Ramp Selections
      7. 8.4.7  Switching Frequency
      8. 8.4.8  Clock Sync Point Selection
      9. 8.4.9  Synchronization and Stackable Configuration
      10. 8.4.10 Dual-Phase Stackable Configurations
        1. Configuration 1: Master Sync Out Clock-to-Slave
        2. Configuration 2: Master and Slave Sync to External System Clock
      11. 8.4.11 Operation Mode
      12. 8.4.12 API/BODY Brake
      13. 8.4.13 Sense and Overcurrent Protection
        1. Low-Side MOSFET Overcurrent Protection
        2. High-Side MOSFET Overcurrent Protection
      14. 8.4.14 Output Overvoltage and Undervoltage Protection
      15. 8.4.15 Overtemperature Protection
      16. 8.4.16 RSP/RSN Remote Sense Function
      17. 8.4.17 Current Sharing
      18. 8.4.18 Loss of Synchronization
  9. Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application: TPS543C20 Stand-alone Device
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. Custom Design With WEBENCH® Tools
        2. Switching Frequency Selection
        3. Inductor Selection
        4. Input Capacitor Selection
        5. Bootstrap Capacitor Selection
        6. BP Pin
        7. R-C Snubber and VIN Pin High-Frequency Bypass
        8. Output Capacitor Selection
          1. Response to a Load Transient
          2. Ramp Selection Design to Ensure Stability
      3. 9.2.3 Application Curves
    3. 9.3 System Example
      1. 9.3.1 Two-Phase Stackable
        1. Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
    3. 11.3 Package Size, Efficiency and Thermal Performance
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Development Support
        1. Custom Design With WEBENCH® Tools
      2. 12.1.2 Documentation Support
        1. Related Documentation
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Community Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

Input Capacitor Selection

The TPS543C20 devices require a high-quality, ceramic, type X5R or X7R, input decoupling capacitor with a value of at least 1 μF of effective capacitance on the VDD pin, relative to AGND. The power stage input decoupling capacitance (effective capacitance at the PVIN and PGND pins) must be sufficient to supply the high switching currents demanded when the high-side MOSFET switches on, while providing minimal input voltage ripple as a result. This effective capacitance includes any DC bias effects. The voltage rating of the input capacitor must be greater than the maximum input voltage. The capacitor must also have a ripple current rating greater than the maximum input current ripple to the device during full load. The input ripple current can be calculated using Equation 6.

Equation 6. TPS543C20 Eq_Icin_rms_SLUSCD4.gif

The minimum input capacitance and ESR values for a given input voltage ripple specification, VIN(ripple), are shown in Equation 7 and Equation 8. The input ripple is composed of a capacitive portion, VRIPPLE(cap), and a resistive portion, VRIPPLE(esr).

Equation 7. TPS543C20 eq_cinmin_slusc70.gif
Equation 8. TPS543C20 eq_esrcinmax_slusc70.gif

The value of a ceramic capacitor varies significantly over temperature and the amount of DC bias applied to the capacitor. The capacitance variations due to temperature can be minimized by selecting a dielectric material that is stable over temperature. X5R and X7R ceramic dielectrics are usually selected for power regulator capacitors because they have a high capacitance to volume ratio and are fairly stable over temperature. The input capacitor must also be selected with the DC bias taken into account. For this example design, a ceramic capacitor with at least a 25-V voltage rating is required to support the maximum input voltage. For this design, allow 0.1-V input ripple for VRIPPLE(cap), and 0.3-V input ripple for VRIPPLE(esr). Using Equation 7 and Equation 8, the minimum input capacitance for this design is 38.5 µF, and the maximum ESR is 9.4 mΩ. For this example, four 22-μF, 25-V ceramic capacitors and one additional 100-μF, 25-V low-ESR polymer capacitors in parallel were selected for the power stage.