SLVSGC9A May   2023  – February 2024 TPS543A22

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1  VIN Pins and VIN UVLO
      2. 6.3.2  Internal Linear Regulator and Bypassing
      3. 6.3.3  Enable and Adjustable UVLO
        1. 6.3.3.1 Internal Sequence of Events During Start-Up
      4. 6.3.4  Switching Frequency Selection
      5. 6.3.5  Switching Frequency Synchronization to an External Clock
        1. 6.3.5.1 Internal PWM Oscillator Frequency
        2. 6.3.5.2 Loss of Synchronization
        3. 6.3.5.3 Interfacing the SYNC/FSEL Pin
      6. 6.3.6  Remote Sense Amplifier and Adjusting the Output Voltage
      7. 6.3.7  Loop Compensation Guidelines
        1. 6.3.7.1 Output Filter Inductor Tradeoffs
        2. 6.3.7.2 Ramp Capacitor Selection
        3. 6.3.7.3 Output Capacitor Selection
        4. 6.3.7.4 Design Method for Good Transient Response
      8. 6.3.8  Soft Start and Prebiased Output Start-Up
      9. 6.3.9  MSEL Pin
      10. 6.3.10 Power Good (PG)
      11. 6.3.11 Output Overload Protection
        1. 6.3.11.1 Positive Inductor Current Protection
        2. 6.3.11.2 Negative Inductor Current Protection
      12. 6.3.12 Output Overvoltage and Undervoltage Protection
      13. 6.3.13 Overtemperature Protection
      14. 6.3.14 Output Voltage Discharge
    4. 6.4 Device Functional Modes
      1. 6.4.1 Forced Continuous-Conduction Mode
      2. 6.4.2 Discontinuous Conduction Mode During Soft Start
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Applications
      1. 7.2.1 1.0-V Output, 1-MHz Application
        1. 7.2.1.1 Design Requirements
        2. 7.2.1.2 Detailed Design Procedure
          1. 7.2.1.2.1  Custom Design With WEBENCH® Tools
          2. 7.2.1.2.2  Switching Frequency
          3. 7.2.1.2.3  Output Inductor Selection
          4. 7.2.1.2.4  Output Capacitor
          5. 7.2.1.2.5  Input Capacitor
          6. 7.2.1.2.6  Adjustable Undervoltage Lockout
          7. 7.2.1.2.7  Output Voltage Resistors Selection
          8. 7.2.1.2.8  Bootstrap Capacitor Selection
          9. 7.2.1.2.9  VDRV and VCC Capacitor Selection
          10. 7.2.1.2.10 PGOOD Pullup Resistor
          11. 7.2.1.2.11 Current Limit Selection
          12. 7.2.1.2.12 Soft-Start Time Selection
          13. 7.2.1.2.13 Ramp Selection and Control Loop Stability
          14. 7.2.1.2.14 MODE Pin
        3. 7.2.1.3 Application Curves
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
      2. 7.4.2 Layout Example
      3. 7.4.3 Thermal Performance
  9. 8 Device and Documentation Support
    1. 8.1 Device Support
      1. 8.1.1 Development Support
        1. 8.1.1.1 Custom Design With WEBENCH® Tools
    2. 8.2 Receiving Notification of Documentation Updates
    3. 8.3 Support Resources
    4. 8.4 Trademarks
    5. 8.5 Electrostatic Discharge Caution
    6. 8.6 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information
7.2.1.2.3 Output Inductor Selection

To calculate the value of the output inductor, use Equation 16. KIND is a ratio that represents the amount of inductor ripple current relative to the maximum output current. The inductor ripple current is filtered by the output capacitor. Therefore, choosing high inductor ripple currents impacts the selection of the output capacitor because the output capacitor must have a ripple current rating equal to or greater than the inductor ripple current. Choosing small inductor ripple currents can degrade the transient response performance. The inductor ripple, KIND, is normally from 0.1 to 0.4 for the majority of applications giving a peak to peak ripple current range of 2 A to 8 A. The target IRIPPLE must be 1 A or larger.

For this design example, KIND = 0.2 is used and the inductor value is calculated to be 0.394 µH. An inductor with an inductance of 0.300 µH is selected. It is important that the RMS (root mean square) current and saturation current ratings of the inductor not be exceeded. The RMS and peak inductor current can be found from Equation 18 and Equation 19. For this design, the RMS inductor current is 12.49A, and the peak inductor current is 13.749 A. The chosen inductor is a SLR1070-301KE. The inductor has a saturation current rating of 31 A, an RMS current rating of 61 A, and a typical DC series resistance of 0.39 mΩ.

The peak current through the inductor is the inductor ripple current plus the output current. During power up, faults, or transient load conditions, the inductor current can increase above the calculated peak inductor current level calculated in Equation 19. In transient conditions, the inductor current can increase up to the switch current limit of the device. For this reason, the most conservative approach is to specify the current ratings of the inductor based on the switch current limit rather than the steady-state peak inductor current.

Equation 16. L 1 =   V I N   -   V O U T   I o   ×   K I N D × V O U T V I N × 1 f S W
Equation 17. I r i p p l e =   V I N M A X   -   V O U T   L 1 × V O U T   V I N M A X   ×   f S W  
Equation 18. I L r m s =   I O 2 + 1 12 × V I N M A X   -   V O U T L 1 × V O U T   V I N M A X   ×   f S W   2
Equation 19. I L p e a k = I O U T + I r i p p l e 2