SNVSAZ4A February   2021  – March 2021 TPS541620

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Fixed-Frequency, Internally Compensated Advanced-Current-Mode Control
      2. 7.3.2  Enable and UVLO
      3. 7.3.3  Internal LDO
      4. 7.3.4  Pre-biased Output Start-up
      5. 7.3.5  Current Sharing
      6. 7.3.6  Frequency Selection and Minimum On-Time and Off-Time
      7. 7.3.7  Ramp Compensation Selection
      8. 7.3.8  Soft Start
      9. 7.3.9  Remote Sense Function
      10. 7.3.10 Adjustable Output Voltage
      11. 7.3.11 Power Good
      12. 7.3.12 Overcurrent Protection
      13. 7.3.13 Overvoltage and Undervoltage Protection
      14. 7.3.14 Overtemperature Protection
      15. 7.3.15 Frequency Synchronization
    4. 7.4 Device Functional Modes
      1. 7.4.1 Operation Mode
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application - Dual Independent Outputs
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1  Switching Frequency
        2. 8.2.2.2  Output Inductor Selection
        3. 8.2.2.3  Output Capacitor
        4. 8.2.2.4  Input Capacitor
        5. 8.2.2.5  Output Voltage Resistors Selection
        6. 8.2.2.6  Adjustable Undervoltage Lockout
        7. 8.2.2.7  Bootstrap Capacitor Selection
        8. 8.2.2.8  BP5 Capacitor Selection
        9. 8.2.2.9  PGOOD Pullup Resistor
        10. 8.2.2.10 Current Limit
        11. 8.2.2.11 Soft-Start Time Selection
        12. 8.2.2.12 MODE1 and MODE2 Pins
      3. 8.2.3 Application Curves
      4. 8.2.4 Typical Application - 2-Phase Operation
        1. 8.2.4.1 Design Requirements
        2. 8.2.4.2 Detailed Design Procedure
          1. 8.2.4.2.1  Switching Frequency
          2. 8.2.4.2.2  Output Inductor Selection
          3. 8.2.4.2.3  Output Capacitor
          4. 8.2.4.2.4  Input Capacitor
          5. 8.2.4.2.5  Output Voltage Resistors Selection
          6. 8.2.4.2.6  Adjustable Undervoltage Lockout
          7. 8.2.4.2.7  Bootstrap Capacitor Selection
          8. 8.2.4.2.8  BP5 Capacitor Selection
          9. 8.2.4.2.9  PGOOD Pullup Resistor
          10. 8.2.4.2.10 Current Limit
          11. 8.2.4.2.11 Soft-Start Time Selection
          12. 8.2.4.2.12 MODE1 Pin
        3. 8.2.4.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
      1. 10.2.1 Thermal Performance
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Support Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information
8.2.4.2.11 Soft-Start Time Selection

The SS pin is used to program different soft-start times in multi-phase mode. In dual-output mode, an internally fixed soft start is used.

This is useful if a load has specific timing requirements for the output voltage of the regulator. A longer soft-start time is also useful if the output capacitance is very large and would require large amounts of current to quickly charge the output capacitors to the output voltage level. The large currents necessary to charge the capacitor can reach the current limit or cause the input voltage rail to sag due excessive current draw from the input power supply. Limiting the output voltage slew rate solves both of these problems. The example design has the soft-start time set to 2.5 ms.