SLVSHN0A September   2024  – October 2025 TPS548B23

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  D-CAP4 Control
      2. 6.3.2  Internal VCC LDO and Using External Bias On the VCC Pin
        1. 6.3.2.1 Powering the Device From a Single Bus
        2. 6.3.2.2 Powering the Device From a Split-Rail Configuration
      3. 6.3.3  Multifunction Configuration (CFG1-5) Pins
        1. 6.3.3.1 Multifunction Configuration (CFG1-2) Pins (Internal Feedback)
        2. 6.3.3.2 Multifunction Configuration (CFG1-2) Pins (External Feedback)
        3. 6.3.3.3 Multifunction Configuration (CFG3-5) Pins
      4. 6.3.4  Enable
      5. 6.3.5  Soft Start
      6. 6.3.6  Power Good
      7. 6.3.7  Overvoltage and Undervoltage Protection
      8. 6.3.8  Output Voltage Setting (External Feedback Configuration)
      9. 6.3.9  Remote Sense
      10. 6.3.10 Low-side MOSFET Zero-Crossing
      11. 6.3.11 Current Sense and Positive Overcurrent Protection
      12. 6.3.12 Low-side MOSFET Negative Current Limit
      13. 6.3.13 Output Voltage Discharge
      14. 6.3.14 UVLO Protection
      15. 6.3.15 Thermal Shutdown
    4. 6.4 Device Functional Modes
      1. 6.4.1 Auto-Skip (PFM) Eco-mode Light Load Operation
      2. 6.4.2 Forced Continuous-Conduction Mode
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
        1. 7.2.2.1 Output Voltage Setting Point
        2. 7.2.2.2 Choose the Switching Frequency
        3. 7.2.2.3 Choose the Inductor
        4. 7.2.2.4 Choose the Output Capacitor
        5. 7.2.2.5 Choose the Input Capacitors (CIN)
        6. 7.2.2.6 VCC Bypass Capacitor
        7. 7.2.2.7 BOOT Capacitor
        8. 7.2.2.8 PG Pullup Resistor
      3. 7.2.3 Application Curves
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
      2. 7.4.2 Layout Example
  9. 8 Device and Documentation Support
    1. 8.1 Documentation Support
      1. 8.1.1 Related Documentation
    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

7.2.2.3 Choose the Inductor

To calculate the value of the output inductor (LOUT), use Equation 13. The output capacitor filters the inductor-ripple current (IIND(ripple)). Therefore, selecting a high inductor-ripple current 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. Larger ripple current increases output ripple voltage, but improves signal-to-noise ratio and helps to stabilize operation. Generally speaking, the inductance value must set the ripple current at approximately 15% to 40% of the maximum output current for a balanced performance.

For this design, the inductor-ripple current is set to 30% of 30A output current. With a 800klHz switching frequency, 16V as maximum VIN, and 3.3V as the output voltage, Based on these parameters, Equation 13 calculates an inductance of 0.546μH . A nearest standard value of 0.55µH is chosen.

Equation 13. L = V I N m a x - V O U T × V O U T I R I P P L E × V I N m a x × f S W = 16   V - 3.3   V × 3.3   V 0.3 × 20 A × 16   V × 800   k H z = 0.546   μ H

The inductor requires a low DCR to achieve good efficiency. The inductor also requires enough room above peak inductor current before saturation. Use Equation 14 to estimate the inductor current ripple. For this design, by tying the XXX pin to VCC, IOC(valley) is set to 21A, thus peak inductor current under maximum VIN is calculated as 22.98A with Equation 15.

Equation 14. I R I P P L E = V I N m a x - V O U T × V O U T L × V I N m a x × f S W = 16   V - 3.3   V × 3.3   V 0.55 μ H × 16   V × 800   k H z = 5.95   A
Equation 15. I L ( P E A K ) = I O U T + I R I P P L E 2 = 20   A + 5.95   A 2 = 22.98   A
Equation 16. I L R M S = I O U T 2 + I R I P P L E 2 12 = 20   A 2 + 5.95   A 2 12 = 20.07   A

The selected inductance is a Coilcraft XAL7070-551MEB. This inductance has a saturation current rating of 43A , RMS current rating of 29A and a DCR of 1.6mΩ maximum. This inductor was selected for the low DCR to get high efficiency.