SNVSCU9A May   2025  – November 2025 TPS7H4012-SEP , TPS7H4013-SEP

PRODMIX  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison Table
  6. 5 Device Options Table
  7. 6 Pin Configuration and Functions
  8. 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 Quality Conformance Inspection
    7. 7.7 Typical Characteristics
  9. 8 Parameter Measurement Information
  10. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1 VIN and Power VIN Pins (VIN and PVIN)
      2. 9.3.2 Voltage Reference
      3. 9.3.3 Voltage Sensing and Setting VOUT
        1. 9.3.3.1 Minimum Output Voltage
        2. 9.3.3.2 Maximum Output Voltage
      4. 9.3.4 Enable
      5. 9.3.5 Power Good (PWRGD)
      6. 9.3.6 Adjustable Switching Frequency and Synchronization
        1. 9.3.6.1 Internal Clock Mode
        2. 9.3.6.2 External Clock Mode
      7. 9.3.7 Turn-On Behavior
        1. 9.3.7.1 Soft-Start (SS_TR)
        2. 9.3.7.2 Safe Start-Up Into Prebiased Outputs
        3. 9.3.7.3 Tracking and Sequencing
      8. 9.3.8 Protection Modes
        1. 9.3.8.1 Overcurrent Protection
          1. 9.3.8.1.1 High-Side 1 Overcurrent Protection (HS1)
          2. 9.3.8.1.2 High-Side 2 Overcurrent Protection (HS2)
          3. 9.3.8.1.3 COMP Shutdown
          4. 9.3.8.1.4 Low-Side Overcurrent Sinking Protection
        2. 9.3.8.2 Output Overvoltage Protection (OVP)
        3. 9.3.8.3 Thermal Shutdown
      9. 9.3.9 Error Amplifier and Loop Response
        1. 9.3.9.1 Error Amplifier
        2. 9.3.9.2 Power Stage Transconductance
        3. 9.3.9.3 Slope Compensation
        4. 9.3.9.4 Frequency Compensation
    4. 9.4 Device Functional Modes
  11. 10Application and Implementation
    1. 10.1 Application Information
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
        1. 10.2.2.1  Operating Frequency
        2. 10.2.2.2  Output Inductor Selection
        3. 10.2.2.3  Output Capacitor Selection
        4. 10.2.2.4  Input Capacitor Selection
        5. 10.2.2.5  Soft-Start Capacitor Selection
        6. 10.2.2.6  Rising VIN Set Point (Configurable UVLO)
        7. 10.2.2.7  Output Voltage Feedback Resistor Selection
        8. 10.2.2.8  Output Voltage Accuracy
        9. 10.2.2.9  Slope Compensation Requirements
        10. 10.2.2.10 Compensation Component Selection
        11. 10.2.2.11 Schottky Diode
      3. 10.2.3 Application Curve
      4. 10.2.4 Inverting Buck-Boost
    3. 10.3 Power Supply Recommendations
    4. 10.4 Layout
      1. 10.4.1 Layout Guidelines
      2. 10.4.2 Layout Example
  12. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Third-Party Products Disclaimer
      2. 11.1.2 Related Documentation
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Support Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  13. 12Revision History
  14. 13Mechanical, Packaging, and Orderable Information
    1.     82

10.2.2.2 Output Inductor Selection

To calculate the value of the output inductor, use Equation 10. KL is a coefficient that represents the amount of inductor ripple current relative to the maximum output current, IOUT, as shown in Equation 9. Since the output capacitors must have a ripple current rating greater than or equal to the inductor ripple current, choosing a high inductor ripple current impacts output capacitors selection. In general, the inductor ripple value is at the discretion of the designer depending on specific system needs. Typical values for KL range from 10% to 50%. For low output currents, the value of KL could be increased to reduce the value of the output inductor.

Equation 9. KL=IrippleIOUT
Equation 10. L=VIN(max)-VOUTIOUT×KL×VOUTVIN(max)×fSW

For this design example, use KL = 35% and VIN(max) = 12.6V (12V + 5%). The calculated inductor value is 2.32µH and the closest available inductor of 2.2µH is selected. The resulting ripple current can be calculated using Equation 11. It is found to be 2.2A for this design.

Equation 11. ∆IL=VIN(max)-VOUTL×VOUTVIN(max)× fSW

For the output filter inductor, it is important that the RMS current and saturation current ratings not be exceeded. The RMS current can be found from Equation 12 and peak inductor current can be found from Equation 13.

Equation 12. I L ( r m s ) = I O U T 2 + 1 12 × ( V O U T × ( V I N m a x - V O U T ) V I N ( m a x ) × L × f S W ) 2
Equation 13. IL(peak)=IOUT+IL(ripple)2

For this design, the RMS inductor current is 6A, and the peak inductor current is 7.11A. To satisfy this requirement, a Wurth 74439346022 inductor is selected. This inductor has a saturation current rating of 19.5A and an RMS current rating of 10.6A.

The current flowing 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 previously calculated peak inductor current level. 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 an inductor with a saturation current rating equal to or greater than the maximum switch current limit, rather than the peak inductor current.

It is suggested to ensure the typical current limit value is at least 25% higher than the peak inductor current to make sure there is sufficient margin before the current limit is engaged. The typical current limit of 9.7A meets these requirements.