SLVSAM8D July   2013  – August 2019 TPS63050 , TPS63051

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified Schematic (WCSP)
      2.      Efficiency vs Output Current
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
    1.     Pin Functions
  7. 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 Switching Characteristics
    7. 7.7 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagrams
    3. 8.3 Feature Description
      1. 8.3.1 Power Good
      2. 8.3.2 Overvoltage Protection
      3. 8.3.3 Undervoltage Lockout (UVLO)
      4. 8.3.4 Thermal Shutdown
      5. 8.3.5 Soft Start
      6. 8.3.6 Short Circuit Protection
    4. 8.4 Device Functional Modes
      1. 8.4.1 Control Loop Description
      2. 8.4.2 Power Save Mode Operation
      3. 8.4.3 Adjustable Current Limit
      4. 8.4.4 Device Enable
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Custom Design With WEBENCH® Tools
        2. 9.2.2.2 Output Filter Design
        3. 9.2.2.3 Inductor Selection
        4. 9.2.2.4 Capacitor selection
          1. 9.2.2.4.1 Input Capacitor
          2. 9.2.2.4.2 Output Capacitor
        5. 9.2.2.5 Setting the Output Voltage
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example (WCSP)
    3. 11.3 Layout Example (HotRod)
    4. 11.4 Thermal Considerations
  12. 12Device and Documentation Support
    1. 12.1 Custom Design With WEBENCH® Tools
    2. 12.2 Device Support
      1. 12.2.1 Third-Party Products Disclaimer
    3. 12.3 Related Links
    4. 12.4 Receiving Notification of Documentation Updates
    5. 12.5 Community Resources
    6. 12.6 Trademarks
    7. 12.7 Electrostatic Discharge Caution
    8. 12.8 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

8.3.5 Soft Start

To minimize inrush current and output voltage overshoot during start up, the device has a soft start. At turn on, the input current raises monotonically until the output voltage reaches regulation. The TPS6305x devices charge the soft start capacitor, at the SS pin, with a constant current of typically 1 µA. The input current follows the current used to charge the capacitor at the SS pin. The soft start operation is completed once the voltage at the SS pin has reached typically 1.3 V. Figure 3 shows the value of the soft start capacitor in respect to the soft-start time.

The soft-start time is the time from when the EN pin is asserted to when the output voltage has reached 90% of its nominal value. There is typically a 100-µs delay time from EN pin assertion to the start of the switching activity. The soft-start time depends on the load current, the input voltage, and the output capacitor. The soft-start time in boost mode is longer then the time in buck mode and it also depends on the load current, input voltage and output capacitor.

The soft-start time in Figure 3 is referred to typical application with 10-µF effective output capacitance.

The inductor current is able to increase and always assure a soft start unless a real short circuit is applied at the output.