SLVSC55C August   2013  – November 2021 TPS62090-Q1

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  Enable and Disable (EN)
      2. 7.3.2  Soft Start (SS) and Hiccup Current Limit During Start-Up
      3. 7.3.3  Voltage Tracking (SS)
      4. 7.3.4  Short-Circuit Protection (Hiccup Mode)
      5. 7.3.5  Output Discharge Function
      6. 7.3.6  Power Good Output (PG)
      7. 7.3.7  Frequency Set Pin (FREQ)
      8. 7.3.8  Undervoltage Lockout (UVLO)
      9. 7.3.9  Thermal Shutdown
      10. 7.3.10 Charge Pump (CP, CN)
    4. 7.4 Device Functional Modes
      1. 7.4.1 Pulse Width Modulation Operation
      2. 7.4.2 Power Save Mode Operation
      3. 7.4.3 Low-Dropout Operation (100% Duty Cycle)
  8. 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 Inductor Selection
        2. 8.2.2.2 Input and Output Capacitor Selection
        3. 8.2.2.3 Setting the Output Voltage
      3. 8.2.3 Application Curves
    3. 8.3 System Examples
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Receiving Notification of Documentation Updates
    4. 11.4 Support Resources
    5. 11.5 Trademarks
    6. 11.6 Electrostatic Discharge Caution
    7. 11.7 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

7.3.2 Soft Start (SS) and Hiccup Current Limit During Start-Up

To minimize inrush current during start-up, the device has an adjustable soft start depending on the capacitor value connected to the SS pin. The device charges the soft-start capacitor with a constant current of typically
7.5 µA. The feedback voltage follows this voltage with a fraction of 1.56 until the internal reference voltage of 0.8 V is reached. The soft-start operation is complete when the voltage at the soft-start capacitor has reached typically 1.25 V. The soft-start time is calculated using Equation 1. The larger the soft-start capacitor, the longer the soft-start time. The relation between soft-start voltage and feedback voltage is estimated using Equation 2.

Equation 1. GUID-FF066E9A-54BF-4615-9C74-E977B7533565-low.gif
Equation 2. GUID-0D561675-6D15-4412-A7D7-C57807A94911-low.gif

During start-up, the switch current limit is reduced to 1/3 (approximately 1.5 A) of its typical current limit of 4.6 A. Once the output voltage exceeds typically 0.6 V, the current limit is released to its nominal value. The device provides a reduced load current of approximately 1.5 A when the output voltage is below typically 0.6 V. Due to this, a small or no soft-start time may trigger the short-circuit protection during start-up especially for larger output capacitors. This is avoided by using a larger soft-start capacitance to extend the soft-start time. See Section 7.3.4 for details of the reduced current limit during start-up. Leaving the soft-start pin floating sets the minimum start-up time (around 50 µs).