SLVSFC5 November   2020 TPS552882

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and 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  VCC Power Supply
      2. 7.3.2  Operation Mode Setting
      3. 7.3.3  Input Undervoltage Lockout
      4. 7.3.4  Enable and Programmable UVLO
      5. 7.3.5  Soft Start
      6. 7.3.6  Shutdown
      7. 7.3.7  Switching Frequency
      8. 7.3.8  Switching Frequency Dithering
      9. 7.3.9  Inductor Current Limit
      10. 7.3.10 Internal Charge Path
      11. 7.3.11 Output Voltage Setting
      12. 7.3.12 Output Current Indication and Cable Voltage Drop Compensation
      13. 7.3.13 Integrated Gate Drivers
      14. 7.3.14 Output Current Limit
      15. 7.3.15 Overvoltage Protection
      16. 7.3.16 Output Short Circuit Protection
      17. 7.3.17 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 PWM Mode
      2. 7.4.2 Power Save Mode
  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 5V Power Supply Detailed Design Procedure
        1. 8.2.2.1 Custom Design With WEBENCH® Tools
        2. 8.2.2.2 Switching Frequency
        3. 8.2.2.3 Output Voltage Setting
        4. 8.2.2.4 Inductor Selection
        5. 8.2.2.5 Input Capacitor
        6. 8.2.2.6 Output Capacitor
        7. 8.2.2.7 Output Current Limit
        8. 8.2.2.8 Loop Stability
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  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 Support Resources
    4. 11.4 Trademarks
    5. 11.5 Glossary
    6. 11.6 Electrostatic Discharge Caution

Package Options

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

8.2.2.6 Output Capacitor

In boost mode, the output capacitor conducts high ripple current. The output capacitor RMS ripple current is given by Equation 15, where the minimum input voltage and the maximum output voltage correspond to the maximum capacitor current.

Equation 15. GUID-26452432-D350-4170-BF71-987B00E9C4EC-low.gif

where

  • ICOUT(RMS) is the RMS current through the output capacitor
  • IOUT is the output current

In this example, the maximum output ripple RMS current is 5.5 A.

The ESR of the output capacitor causes an output voltage ripple given by Equation 16 in boost mode.

Equation 16. GUID-39ED80AE-7444-40A6-8B8D-D37C16BA3863-low.gif

where

  • RCOUT is the ESR of the output capacitance

The capacitance also causes a capacitive output voltage ripple given by Equation 17 in boost mode. When input voltage reaches the minimum value and the output voltage reaches the maximum value, there is the largest output voltage ripple caused by the capacitance.

Equation 17. GUID-8C84891A-10D2-4C97-8037-CF57CEC0EA54-low.gif

Typically, a combination of ceramic capacitors and bulk electrolytic capacitors is needed to provide low ESR, high ripple current, and small output voltage ripple. From the required output voltage ripple, use Equation 16 and Equation 17 to calculate the minimum required effective capacitance of the COUT.