SLVSAM8D July   2013  – August 2019 TPS63050 , TPS63051

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified Schematic (WCSP)
      2.      Efficiency vs Output Current
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
    1.     Pin Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Switching Characteristics
    7. 7.7 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagrams
    3. 8.3 Feature Description
      1. 8.3.1 Power Good
      2. 8.3.2 Overvoltage Protection
      3. 8.3.3 Undervoltage Lockout (UVLO)
      4. 8.3.4 Thermal Shutdown
      5. 8.3.5 Soft Start
      6. 8.3.6 Short Circuit Protection
    4. 8.4 Device Functional Modes
      1. 8.4.1 Control Loop Description
      2. 8.4.2 Power Save Mode Operation
      3. 8.4.3 Adjustable Current Limit
      4. 8.4.4 Device Enable
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Custom Design With WEBENCH® Tools
        2. 9.2.2.2 Output Filter Design
        3. 9.2.2.3 Inductor Selection
        4. 9.2.2.4 Capacitor selection
          1. 9.2.2.4.1 Input Capacitor
          2. 9.2.2.4.2 Output Capacitor
        5. 9.2.2.5 Setting the Output Voltage
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example (WCSP)
    3. 11.3 Layout Example (HotRod)
    4. 11.4 Thermal Considerations
  12. 12Device and Documentation Support
    1. 12.1 Custom Design With WEBENCH® Tools
    2. 12.2 Device Support
      1. 12.2.1 Third-Party Products Disclaimer
    3. 12.3 Related Links
    4. 12.4 Receiving Notification of Documentation Updates
    5. 12.5 Community Resources
    6. 12.6 Trademarks
    7. 12.7 Electrostatic Discharge Caution
    8. 12.8 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

9.2.2.3 Inductor Selection

The inductor selection is affected by several parameter like inductor ripple current, output voltage ripple, transition point into power save mode, and efficiency. See Table 5 for typical inductors.

Table 5. List of Recommended Inductors

INDUCTOR VALUE COMPONENT SUPPLIER(1) SIZE (L × W × H mm) Isat / DCR
1 µH TOKO 1286AS-H-1R0M 2 × 1.6 × 1.2 2.1 A / 68 mΩ
1.5 µH TOKO, 1286AS-H-1R5M 2 × 1.6 × 1.2 2.5 A / 95 mΩ
1.5 µH TOKO, 1269AS-H-1R5M 2.5 × 2 × 1 2.1 A / 90 mΩ
2.2 µH TOKO 1286AS-H-2R2M 2 × 1.6 × 1.2 2 A / 160 mΩ
(1) See the Third Party Product Disclaimer section.

For high efficiencies, the inductor must have a low dc resistance to minimize conduction losses. Especially at high-switching frequencies, the core material has a high impact on efficiency. When using small chip inductors, the efficiency is reduced mainly due to higher inductor core losses. This needs to be considered when selecting the appropriate inductor. The inductor value determines the inductor ripple current. The larger the inductor value, the smaller the inductor ripple current and the lower the conduction losses of the converter. Conversely, larger inductor values cause a slower load transient response. To avoid saturation of the inductor, the peak current for the inductor in steady state operation is calculated using Equation 6. Only the equation which defines the switch current in boost mode is shown, because this provides the highest value of current and represents the critical current value for selecting inductor.

Equation 5. TPS63050 TPS63051 q1_boost_lvsa92.gif

where

  • D = Duty Cycle in Boost mode
Equation 6. TPS63050 TPS63051 peak_current_boost_lvsa92.gif

where

  • η = Estimated converter efficiency (use the number from the efficiency curves or 0.80 as an assumption)
    f = Converter switching frequency (typical 2.5MHz)
    L = Inductor value

NOTE

The calculation must be done for the minimum input voltage that is possible to have in boost mode.

Calculating the maximum inductor current using the actual operating conditions gives the minimum saturation current of the inductor needed. It's recommended to choose an inductor with a saturation current 20% higher than the value calculated using Equation 6. Possible inductors are listed in Table 5.