SLVSBX8B May   2013  – January 2019 TPS55330

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Typical Application (Boost)
      2.      Efficiency vs Output Current
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Operation
      2. 7.3.2 Switching Frequency
      3. 7.3.3 Overcurrent Protection and Frequency Foldback
        1. 7.3.3.1 Minimum On-Time and Pulse Skipping
      4. 7.3.4 Voltage Reference and Setting Output Voltage
      5. 7.3.5 Soft-Start
      6. 7.3.6 Slope Compensation
      7. 7.3.7 Enable and Thermal Shutdown
      8. 7.3.8 Undervoltage Lockout (UVLO)
    4. 7.4 Device Functional Modes
      1. 7.4.1 Operation With VI < 2.9 V (Minimum VI)
      2. 7.4.2 Operation With EN Control
      3. 7.4.3 Operation at Light Loads
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1  Custom Design With WEBENCH® Tools
        2. 8.2.2.2  Selecting the Switching Frequency (R4)
        3. 8.2.2.3  Determining the Duty Cycle
        4. 8.2.2.4  Selecting the Inductor (L1)
        5. 8.2.2.5  Computing the Maximum Output Current
        6. 8.2.2.6  Selecting the Output Capacitor (C8-C10)
        7. 8.2.2.7  Selecting the Input Capacitors (C2, C7)
        8. 8.2.2.8  Setting Output Voltage (R1, R2)
        9. 8.2.2.9  Setting the Soft-start Time (C7)
        10. 8.2.2.10 Selecting the Schottky Diode (D1)
        11. 8.2.2.11 Compensating the Control Loop (R3, C4, C5)
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
    3. 10.3 Thermal Considerations
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
      2. 11.1.2 Development Support
        1. 11.1.2.1 Custom Design With WEBENCH® Tools
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Community Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

8.2.2.7 Selecting the Input Capacitors (C2, C7)

At least 4.7µF of ceramic input capacitance is recommended. Additional input capacitance may be required to meet ripple and/or transient requirements. High quality ceramic, type X5R or X7R are recommended to minimize capacitance variations over temperature. The capacitor must also have an RMS current rating greater than the maximum RMS input current of the TPS55330 calculated with Equation 22. The input capacitor must also be rated greater than the maximum input voltage. The input voltage ripple can be calculated with Equation 23.

Equation 22. TPS55330 eq22_ICIrms_lvsbd4.gif
Equation 23. TPS55330 eq23_VIripple_lvsbd4.gif

In the design example, the input RMS current is calculated to be 300 mA. The chosen input capacitor is a 10 µF, 25 V 1210 X7R with 3 mΩ ESR. Although one with a lower voltage rating can be used, a 25 V rated capacitor was chosen to limit the affects of dc bias and to allow it the circuit to be rated for the entire input range of the TPS55330. The input ripple is calculated to be 46 mV. An additional 0.1 µF, 50 V 0603 X5R is located close to the VIN and GND pins for extra decoupling.