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

7.3.8 Soft Start

The soft-start feature is used to prevent inrush current impacting the TPS541620 and its supply when power is first applied. Soft start is achieved by slowly ramping up the target regulation voltage when the device is first enabled or powered up. For dual-output applications, the external soft start is disabled and the outputs turn on with an internally-set soft start time of 1 ms. In this situation, leave the SS pin floating. The external soft start is enabled when the device is configured in multi-phase operation. Multi-phase applications that deliver high load current can have a large amount of capacitance at the output. The soft-start time for such applications can be extended by connecting an external capacitor CSS from the SS pin to AGND to make sure there is no sudden current surge. Extended soft-start time further reduces the supply current required to charge up output capacitors and supply any output loading. An internal current source (ICt_SS = 2 μA) charges CSS and generates a ramp from 0 V to VFB to control the ramp-up rate of the output voltage. The soft-start capacitor CSS is discharged through an internal FET of 600-Ω resistance when VOUT is shut down by fault protection or EN low. The total time required to discharge the soft-start capacitor completely is 500 µs. When a large value of CSS is connected and EN is toggled low only for a short period of time, CSS may not be fully discharged. The next soft-start ramp follows the internal soft-start ramp before reaching the leftover voltage on CSS and then follows the ramp programmed by CSS.