SLUSG02 May   2025 TPS6286A06D

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
  7. 6 Typical Characteristics
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Power Save Mode (PFM)
      2. 7.3.2 Forced PWM Mode
      3. 7.3.3 Low Dropout Operation (100% Duty Cycle)
      4. 7.3.4 Soft Start
      5. 7.3.5 Switch Current Limit and HICCUP Short-Circuit Protection
      6. 7.3.6 Undervoltage Lockout
      7. 7.3.7 Thermal Warning and Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Enable and Disable (EN)
      2. 7.4.2 Output Discharge
      3. 7.4.3 Power Good (PG)
      4. 7.4.4 Voltage Setting and Mode Selection (VSET/MODE)
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Custom Design With WEBENCH® Tools
        2. 8.2.2.2 Setting the Output Voltage
        3. 8.2.2.3 Output Filter Design
        4. 8.2.2.4 Inductor Selection
        5. 8.2.2.5 Capacitor Selection
      3. 8.2.3 Application Curves
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
        1. 8.4.2.1 Thermal Considerations
  10. 9 Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 Third-Party Products Disclaimer
      2. 9.1.2 Development Support
        1. 9.1.2.1 Custom Design With WEBENCH® Tools
    2. 9.2 Documentation Support
      1. 9.2.1 Related Documentation
    3. 9.3 Receiving Notification of Documentation Updates
    4. 9.4 Support Resources
    5. 9.5 Trademarks
    6. 9.6 Electrostatic Discharge Caution
    7. 9.7 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

7.3.4 Soft Start

After enabling the device, there is an enable delay (tdelay) before the device starts switching. After the enable delay, if the SS pin is left not connected, an internal soft start-up circuit controls the output voltage ramp up with a period of 1.5ms (tRamp) for TPS6286A06D. Leaving the SS pin disconnected provides the fastest start-up ramp. Soft start avoids excessive inrush current and creates a smooth output voltage ramp up while also preventing excessive voltage drops of primary cells and rechargeable batteries with high internal impedance. An external soft-start capacitor connected from SS to GND is charged by an internal 20µA current source during soft start until reaching the reference voltage of 0.9V. The capacitance required to set a certain ramp-time (tRAMP) therefore is:

Equation 3. CSS=20µA × trampms0.9V

If the device is set to shutdown (EN = GND), undervoltage lockout, or thermal shutdown, an internal resistor pulls the SS pin to GND. Returning from those states causes a new start-up sequence.

TPS6286A06D Start-Up SequenceFigure 7-1 Start-Up Sequence

The device is able to start into a prebiased output capacitor. The device starts with the applied bias voltage and ramps the output voltage to the nominal value.