SLVS821E May   2008  – May 2019 TPS61087

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 Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Inductor Selection
        2. 8.2.2.2 Rectifier Diode Selection
        3. 8.2.2.3 Setting the Output Voltage
        4. 8.2.2.4 Compensation (COMP)
        5. 8.2.2.5 Input Capacitor Selection
        6. 8.2.2.6 Output Capacitor Selection
      3. 8.2.3 Application Curves
    3. 8.3 System Examples
      1. 8.3.1 General Boost Application Circuits
      2. 8.3.2 TFT LCD Application
      3. 8.3.3 White LED Applications
  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 Third-Party Products Disclaimer
    2. 11.2 Trademarks
    3. 11.3 Electrostatic Discharge Caution
    4. 11.4 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

8.2.2.6 Output Capacitor Selection

For best output voltage filtering a low ESR output capacitor like ceramic capcaitor is recommended. Four 10-μF ceramic output capacitors (or two-22 μF) work for most of the applications. Higher capacitor values can be used to improve the load transient response. See Table 6 for the selection of the output capacitor.

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, the following equation can be used:

Equation 10. TPS61087 q10_lvs821.gif

with

ΔVC Output voltage ripple dependent on output capacitance,output current and switching frequency
VS Output voltage
VIN Minimum input voltage of boost converter
fS Converter switching frequency (typically 1.2 MHz or 650 kHz)
Iout Output capacitance
ΔVC_ESR Output voltage ripple due to output capacitors ESR (equivalent series resistance)
ISWPEAK Inductor peak switch current in the application
RC_ESR Output capacitors equivalent series resistance (ESR)

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