SLVSB50C December   2011  – June 2020 TPS61087-Q1

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified Schematic
  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 Soft Start
      2. 7.3.2 Frequency Select Pin (FREQ)
      3. 7.3.3 Undervoltage Lockout (UVLO)
      4. 7.3.4 Thermal Shutdown
      5. 7.3.5 Overvoltage Prevention
    4. 7.4 Device Functional Modes
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Typical Application Circuit: 5 V to 15 V (fS = 1.2 MHz)
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Inductor Selection
          2. 8.2.1.2.2 Rectifier Diode Selection
          3. 8.2.1.2.3 Setting the Output Voltage
          4. 8.2.1.2.4 Compensation (COMP)
          5. 8.2.1.2.5 Input Capacitor Selection
          6. 8.2.1.2.6 Output Capacitor Selection
      2. 8.2.2 Application Curves
      3. 8.2.3 Other Application Circuit Examples
  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. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Receiving Notification of Documentation Updates
    4. 11.4 Support Resources
    5. 11.5 Trademarks
    6. 11.6 Electrostatic Discharge Caution
    7. 11.7 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

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8.2.1.2.6 Output Capacitor Selection

TI recommends low-ESR ceramic capacitors for best output voltage filtering. Four 10-μF (or two 22-µF) ceramic output capacitors work for most of the applications. Higher capacitor values can be used to improve the load transient response. See Table 6 for output capacitor selection. DC voltage derating factor must also be considered while choosing capacitors. Customers must verify and validate selected components for suitability with their application.

Table 6. Rectifier Input and Output Capacitor Selection

CAPACITOR (SIZE) VOLTAGE RATING SUPPLIER COMPONENT CODE
CIN 22 μF (1206) 16 V Taiyo Yuden EMK316 BJ 226ML
IN bypass 1 μF (0603) 16 V Taiyo Yuden EMK107 BJ 105KA
COUT 10 μF (1206) 25 V Taiyo Yuden TMK316 BJ 106KL

To calculate the output voltage ripple, use Equation 10.

Equation 10. TPS61087-Q1 q10_lvs821.gif

where

  • ΔVC is the output voltage ripple dependent on output capacitance, output current, and switching frequency.
  • ΔVC_ESR is the output voltage ripple due to output capacitors ESR (equivalent series resistance).
  • Iswpeak is the inductor peak switch current in the application.
  • RC_ESR is the output capacitors equivalent series resistance (ESR).

ΔVC_ESR can be neglected in many cases because ceramic capacitors provide low ESR.