SLUS720F February   2007  – June 2019 TPS40195

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified Application Diagram
  4. 4 Revision History
  5. 5 Description (continued)
  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 Electrical Characteristics
    5. 7.5 Dissipation Ratings
    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  Enable Functionality
      2. 8.3.2  Voltage Reference
      3. 8.3.3  Oscillator and Synchronization
      4. 8.3.4  Undervoltage Lockout (UVLO)
      5. 8.3.5  Soft Start
      6. 8.3.6  Selecting the Short Circuit Threshold
      7. 8.3.7  5-V Regulator
      8. 8.3.8  Prebias Start-up
      9. 8.3.9  Drivers
      10. 8.3.10 Power Good
      11. 8.3.11 Thermal Shutdown
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 Typical Application 1
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
          1. 9.2.1.2.1 Output Inductor, LOUT
          2. 9.2.1.2.2 Output Capacitor, COUT
          3. 9.2.1.2.3 Input Capacitor, CIN
          4. 9.2.1.2.4 Switching MOSFET, QSW
          5. 9.2.1.2.5 Rectifier MOSFET, QSR
          6. 9.2.1.2.6 Component Selection for the TPS40195
            1. 9.2.1.2.6.1 Timing Resistor, RT
            2. 9.2.1.2.6.2 Setting UVLO
            3. 9.2.1.2.6.3 Setting the Soft-Start Time
            4. 9.2.1.2.6.4 Short-Circuit Protection, RILIM
            5. 9.2.1.2.6.5 Voltage Decoupling Capacitors, CBP, and CVDD
            6. 9.2.1.2.6.6 Boost Voltage, CBOOST and DBOOST (optional)
            7. 9.2.1.2.6.7 Closing the Feedback Loop RZ1, RP1, RPZ2, RSET1, RSET2, CZ2, CP2 AND CPZ1
          7. 9.2.1.2.7 Application Curve
      2. 9.2.2 Typical Application 2
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
        3. 9.2.2.3 Application Curves
      3. 9.2.3 Typical Application 3
        1. 9.2.3.1 Design Requirements
        2. 9.2.3.2 Detailed Design Procedure
        3. 9.2.3.3 Application Curves
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Examples
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
    2. 11.2 Device Support
      1. 11.2.1 Related Parts
    3. 11.3 Documentation Support
      1. 11.3.1 Related Documentation
    4. 11.4 Receiving Notification of Documentation Updates
    5. 11.5 Community Resources
    6. 11.6 Trademarks
    7. 11.7 Electrostatic Discharge Caution
    8. 11.8 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

9.2.1.2.1 Output Inductor, LOUT

Equation 9 can be used to calculate LOUT.

Equation 9. TPS40195 q_lout01_lus720.gif

where

  • IRIPPLE = the allowable ripple current in the inductor, 20% of maximum IOUT

For this design a 2.5-μH inductor from Coilcraft is used. IRIPPLE is recalculated using Equation 10 and a 2.5-μH inductor value to give a new estimate of IRIPPLE of 2.1 A .

Equation 10. TPS40195 q_irip_lus720.gif

With this IRIPPLE value, the RMS and peak current flowing in LOUTcan be calculated.

Equation 11. TPS40195 q_ilout_lus720.gif
Equation 12. TPS40195 q_ipk_lus720.gif