SLVSHB5A October   2024  – November 2024 TPS61287

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 Enable and Start-up
      2. 6.3.2 Undervoltage Lockout (UVLO)
      3. 6.3.3 Programmable EN/UVLO
      4. 6.3.4 Switching Valley Current Limit
      5. 6.3.5 External Clock Synchronization
      6. 6.3.6 Stackable Multi-phase Operation
      7. 6.3.7 Device Functional Modes
        1. 6.3.7.1 Forced PWM Mode
        2. 6.3.7.2 Auto PFM Mode
      8. 6.3.8 Overvoltage Protection
      9. 6.3.9 Thermal Shutdown
  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 Setting Output Voltage
        2. 7.2.2.2 Inductor Selection
        3. 7.2.2.3 Bootstrap And VCC Capacitors Selection
        4. 7.2.2.4 MOSFET Selection
        5. 7.2.2.5 Input Capacitor Selection
        6. 7.2.2.6 Output Capacitor Selection
        7. 7.2.2.7 Loop Stability
      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
        1. 7.4.2.1 Thermal Considerations
  9. 8 Device and Documentation Support
    1. 8.1 Receiving Notification of Documentation Updates
    2. 8.2 Support Resources
    3. 8.3 Trademarks
    4. 8.4 Electrostatic Discharge Caution
    5. 8.5 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

6.3.1 Enable and Start-up

The TPS61287 has a soft start function to prevent high inrush current during start-up. When the EN/UVLO pin is pulled high, the internal soft-start capacitor is charged with a constant current. During this time, the soft-start capacitor voltage is compared with the internal reference (1.0V). The lower one is fed into the internal positive input of the error amplifier. The output of the error amplifier (which determines the inductor valley current value) ramps up slowly as the soft-start capacitor voltage goes up. The soft-start phase is completed after the soft-start capacitor voltage exceeds the internal reference (1.0V), which takes 7ms from 0V to 1.0V. When the EN pin is pulled low, the voltage of the soft-start capacitor is discharged to ground.