SLVS751F November   2007  – April 2026 TPS5430-Q1

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 (DDA Package)
    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  Oscillator Frequency
      2. 6.3.2  Voltage Reference
      3. 6.3.3  Enable (ENA) and Internal Slow Start
      4. 6.3.4  Undervoltage Lockout (UVLO)
      5. 6.3.5  Boost Capacitor (BOOT)
      6. 6.3.6  Output Feedback (VSENSE) and Internal Compensation
      7. 6.3.7  Voltage Feed Forward
      8. 6.3.8  Pulse-Width Modulation (PWM) Control
      9. 6.3.9  Overcurrent Limiting
      10. 6.3.10 Overvoltage Protection (OVP)
      11. 6.3.11 Thermal Shutdown
    4. 6.4 Device Functional Modes
      1. 6.4.1 Operation near Minimum Input Voltage
      2. 6.4.2 Operation With ENA Control
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Applications
      1. 7.2.1 Application Circuit, 12V to 5V
        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 Input Capacitors
          4. 7.2.1.2.4 Output Filter Components
            1. 7.2.1.2.4.1 Inductor Selection
            2. 7.2.1.2.4.2 Capacitor Selection
          5. 7.2.1.2.5 Output Voltage Setpoint
          6. 7.2.1.2.6 Boot Capacitor
          7. 7.2.1.2.7 Catch Diode
          8. 7.2.1.2.8 Advanced Information
            1. 7.2.1.2.8.1 Output Voltage Limitations
            2. 7.2.1.2.8.2 Internal Compensation Network
            3. 7.2.1.2.8.3 Thermal Calculations
        3. 7.2.1.3 Application Curves
      2. 7.2.2 9V to 21V Input to 5V Output Application Circuit
      3. 7.2.3 Circuit Using Ceramic Output Filter Capacitors
        1. 7.2.3.1 Output Filter Component Selection
        2. 7.2.3.2 External Compensation Network
    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 Device Support
      1. 8.1.1 Development Support
        1. 8.1.1.1 Custom Design With WEBENCH® Tools
    2. 8.2 Documentation Support
      1. 8.2.1 Related Documentation
    3. 8.3 Receiving Notification of Documentation Updates
    4. 8.4 Support Resources
    5. 8.5 Trademarks
    6. 8.6 Electrostatic Discharge Caution
    7. 8.7 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

7.2.3.2 External Compensation Network

When using ceramic output capacitors, additional circuitry is required to stabilize the closed loop system. For this circuit, the external components are R3, C4, C6, and C7. To determine the value of these components, first calculate the LC resonant frequency of the output filter:

Equation 23. TPS5430-Q1

For this example, the effective resonant frequency is calculated as 4109Hz.

The network composed of R1, R2, R3, C5, C6, and C7 has two poles and two zeros that are used to tailor the overall response of the feedback network to accommodate the use of the ceramic output capacitors. The pole and zero locations are given by the following equations:

Equation 24. TPS5430-Q1
Equation 25. TPS5430-Q1
Equation 26. TPS5430-Q1

The final pole is located at a frequency too high to be of concern. The second zero, Fz2 as defined by Equation 26 uses 2.5 for the frequency multiplier. In some cases this can need to be slightly higher or lower. Values in the range of 2.3 to 2.7 work well. The values for R1 and R2 are fixed by the 3.3V output voltage as calculated using Equation 12. For this design R1 = 10kΩ and R2 = 5.90kΩ. With Fp1 = 401Hz, Fz1 = 2876Hz, and Fz2 = 10.3kHz, the values of R3, C6, and C7 are determined using Equation 27, Equation 28, and Equation 29:

Equation 27. TPS5430-Q1
Equation 28. TPS5430-Q1
Equation 29. TPS5430-Q1

For this design, using the closest standard values, C7 is 0.1μF, R3 is 549Ω, and C6 is 1500pF. C4 is added to improve load regulation performance. It is effectively in parallel with C6 in the location of the second pole frequency, so must be small in relationship to C6. C4 must be less the 1/10 the value of C6. For this example, 150pF works well.

For additional information on external compensation of the wide-voltage-range PWM converter devices, see Using TPS5410/20/30/31 With Aluminum/Ceramic Output Capacitors application note.