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

8.2.2.1 Inductor Selection

The inductor selection is affected by several parameters such as inductor-ripple current, output-voltage ripple, transition point into power save mode, and efficiency. See Table 8-4 for typical inductors.

Table 8-4 Inductor Selection
INDUCTOR VALUECOMPONENT SUPPLIERSIZE (L × W × H mm)Isat / DCR
0.6 µHCoilcraft XAL4012-6014 × 4 × 2.17.1 A / 9.5 mΩ
1 µHCoilcraft XAL4020-1024 × 4 × 2.15.9 A / 13.2 mΩ
1 µHCoilcraft XFL4020-1024 × 4 × 2.15.1 A / 10.8 mΩ
0.47 µHTOKO DFE252012 R472.5 × 2 × 1.23.7 A / 39 mΩ
1 µHTOKO DFE252012 1R02.5 × 2 × 1.23.0 A / 59 mΩ
0.68 µHTOKO DFE322512 R683.2 × 2.5 × 1.23.5 A / 37 mΩ
1 µHTOKO DFE322512 1R03.2 × 2.5 × 1.23.1 A / 45 mΩ

In addition, the inductor must be rated for the appropriate saturation current and DC resistance (DCR). The inductor must be rated for a saturation current as high as the typical switch current limit, of 4.6 A or according to Equation 5 and Equation 6. Equation 5 and Equation 6 calculate the maximum inductor current under static load conditions. The formula takes the converter efficiency into account. The converter efficiency is taken from the Section 6.6 graphs or 80% can be used as a conservative approach. The calculation must be done for the maximum input voltage where the peak switch current is highest.

Equation 5. GUID-9B155B1F-3C35-45F3-9FA1-6C11F89BA7EA-low.gif
Equation 6. GUID-13367274-2DEF-4E06-91B4-6205BE5C68FC-low.gif

where

  • ƒ = Converter switching frequency (typical 2.8 MHz or 1.4 MHz)
  • L = Selected inductor value
  • η = Estimated converter efficiency (use the number from the efficiency curves or 0.80 as an conservative assumption)
Note:

The calculation must be done for the maximum input voltage of the application

Calculating the maximum inductor current using the actual operating conditions gives the minimum saturation current. A margin of 20% must be added to cover for load transients during operation.