SLVSEK3 March   2018 TPS62243-Q1 , TPS62244-Q1

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 Undervoltage Lockout
      2. 8.3.2 Enable
      3. 8.3.3 Thermal Shutdown
    4. 8.4 Device Functional Modes
      1. 8.4.1 Soft Start
      2. 8.4.2 Power Save Mode
        1. 8.4.2.1 100% Duty Cycle Low Dropout Operation
      3. 8.4.3 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 Filter Design (Inductor and Output Capacitor)
          1. 9.2.2.1.1 Inductor Selection
          2. 9.2.2.1.2 Output Capacitor Selection
          3. 9.2.2.1.3 Input Capacitor Selection
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Third-Party Products Disclaimer
    2. 12.2 Receiving Notification of Documentation Updates
    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
    1. 13.1 Package Option Addendum
      1. 13.1.1 Packaging Information
      2. 13.1.2 Tape and Reel Information

Package Options

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

9.2.2.1.1 Inductor Selection

The inductor value has a direct effect on the ripple current. The selected inductor must be rated for its DC resistance and saturation current (Table 3). The inductor ripple current (ΔIL) decreases with higher inductance and increases with higher VI or VO.

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

Equation 2 calculates the maximum inductor current in PWM mode 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 the recommendation because during heavy-load transients the inductor current rises above the calculated value.

Equation 2. TPS62243-Q1 TPS62244-Q1 q3_delta_lvs762_.gif
Equation 3. TPS62243-Q1 TPS62244-Q1 q4_ilmax_lvs762.gif

where

  • ƒ = 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 limit ILIMF of the 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 strongly impact 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 3. List of Inductors

INDUCTANCE (μH)DIMENSIONS (mm)PART NUMBERMANUFACTURER(1)
2 2.5 × 2 × 1 MIPS2520D2R2 FDK
2 2.5 × 2 × 1.2 MIPSA2520D2R2 FDK
2.2 2.5 × 2 × 1 KSLI-252010AG2R2 Hitachi Metals
2.2 2.5 × 2 × 1.2 LQM2HPN2R2MJ0L Murata
2.2 3 × 3 × 1.4 LPS3015 Coilcraft