SLVSDG6C May   2016  – March 2026 TPS54302

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 Timing Requirements
    7. 5.7 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  Fixed-Frequency PWM Control
      2. 6.3.2  Pulse Skip Mode
      3. 6.3.3  Error Amplifier
      4. 6.3.4  Slope Compensation and Output Current
      5. 6.3.5  Enable and Adjusting Undervoltage Lockout
      6. 6.3.6  Safe Start-Up into Prebiased Outputs
      7. 6.3.7  Voltage Reference
      8. 6.3.8  Adjusting Output Voltage
      9. 6.3.9  Internal Soft Start
      10. 6.3.10 Bootstrap Voltage (BOOT)
      11. 6.3.11 Overcurrent Protection
        1. 6.3.11.1 High-Side MOSFET Overcurrent Protection
        2. 6.3.11.2 Low-Side MOSFET Overcurrent Protection
      12. 6.3.12 Spread Spectrum
      13. 6.3.13 Output Overvoltage Protection (OVP)
      14. 6.3.14 Thermal Shutdown
    4. 6.4 Device Functional Modes
      1. 6.4.1 Normal Operation
      2. 6.4.2 Eco-mode Operation
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Application
      1. 7.2.1 TPS54302 8V to 28V Input, 5V Output Converter
      2. 7.2.2 Design Requirements
      3. 7.2.3 Detailed Design Procedure
        1. 7.2.3.1 Input Capacitor Selection
        2. 7.2.3.2 Bootstrap Capacitor Selection
        3. 7.2.3.3 Output Voltage Set Point
        4. 7.2.3.4 Undervoltage Lockout Set Point
        5. 7.2.3.5 Output Filter Components
          1. 7.2.3.5.1 Inductor Selection
          2. 7.2.3.5.2 Output Capacitor Selection
          3. 7.2.3.5.3 Feedforward Capacitor
      4. 7.2.4 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 Device Support
      1. 8.1.1 Third-Party Products Disclaimer
    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
7.2.3.5.3 Feedforward Capacitor

The TPS54302 device is internally compensated and the internal compensation network is composed of two capacitors and one resister shown on the Functional Block Diagram. Depending on the VOUT, if the output capacitor COUT is dominated by low ESR (ceramic types) capacitors, it could result in low phase margin. To improve the phase boost an external feedforward capacitor C6 can be added in parallel with R2. The C6 capacitor is chosen such that phase margin is boosted at the crossover frequency.

Equation 16 for C6 is tested.

Equation 16. TPS54302

For this design, C6 = 75 pF. The C6 capacitor is not needed when COUT has high ESR, and C6 calculated from Equation 16 must be reduced with medium ESR. Table 7-2 can be used as a starting point.

Table 7-2 lists some recommended component values.

Table 7-2 Recommended Component Values
VOUT (V)L (µH)COUT (µF)R2 (kΩ)R3 (kΩ)C8 (pF)
1.84.76610049.933
2.55.66610031.647
3.36.84410022.147
5104410013.375
1215441005.23100