SLVS764G June   2007  – April 2018 TPS62290 , TPS62291 , TPS62293

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Typical Application Schematic
      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 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Dynamic Voltage Positioning
      2. 8.3.2 Enable
      3. 8.3.3 Mode Selection
      4. 8.3.4 Undervoltage Lockout
      5. 8.3.5 Thermal Shutdown
    4. 8.4 Device Functional Modes
      1. 8.4.1 Soft-Start
      2. 8.4.2 Power Save Mode
      3. 8.4.3 100% Duty Cycle Low Dropout Operation
      4. 8.4.4 Short-Circuit Protection
  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 Output Voltage Setting
        2. 9.2.2.2 Output Filter Design (Inductor and Output Capacitor)
          1. 9.2.2.2.1 Inductor Selection
          2. 9.2.2.2.2 Output Capacitor Selection
          3. 9.2.2.2.3 Input Capacitor Selection
      3. 9.2.3 Application Curves
    3. 9.3 System Examples
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Third-Party Products Disclaimer
    2. 12.2 Related Links
    3. 12.3 Community Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

9.2.2.2.1 Inductor Selection

The inductor value has a direct effect on the ripple current. The selected inductor has to be rated for its DC resistance and saturation current. The inductor ripple current (ΔIL) decreases with higher inductance and increases with higher VIN or VOUT.

The inductor selection has also impact on the output voltage ripple in PFM mode. Higher inductor values will lead to lower output voltage ripple and higher PFM frequency, lower inductor values will lead to a higher output voltage ripple but lower PFM frequency.

Equation 2 calculates the maximum inductor current under static load conditions. The saturation current of the inductor should be rated higher than the maximum inductor current as calculated with Equation 3. This is recommended because during heavy load transient the inductor current will rise above the calculated value.

Equation 2. TPS62290 TPS62291 TPS62293 q3_delta_lvs763_.gif
Equation 3. TPS62290 TPS62291 TPS62293 q4_ilmax_lvs764.gif

where

  • f = Switching frequency (2.25 MHz typical)
  • L = Inductor value
  • ΔIL = Peak-to-peak inductor ripple current
  • ILmax = Maximum inductor current

A more conservative approach is to select the inductor current rating just for the maximum switch current of the corresponding converter.

Accepting larger values of ripple current allows the use of low inductance values, but results in higher output voltage ripple, greater core losses, and lower output current capability.

The total losses of the coil have a strong impact on the efficiency of the DC/DC conversion and consist of both the losses in the DC resistance R(DC)) and the following frequency-dependent components:

  • The losses in the core material (magnetic hysteresis loss, especially at high switching frequencies)
  • Additional losses in the conductor from the skin effect (current displacement at high frequencies)
  • Magnetic field losses of the neighboring windings (proximity effect)
  • Radiation losses

Table 2. List of Inductors

DIMENSIONS [mm3] INDUCTOR TYPE SUPPLIER(1)
3 × 3 × 1.5 LPS3015 Coilcraft
3 x 3 x 1.5 LQH3NPN2R2NM0 MURATA
3.2 x 2.6 x 1.2 MIPSA3226D2R2 FDK