SLVSB07A July   2011  – March 2018 TPS61256A

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Smallest Solution Size Application
      2.      Efficiency vs. Load 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 Parameter Measurement Information
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Softstart
    3. 8.3 Undervoltage Lockout
    4. 8.4 Thermal Regulation
    5. 8.5 Thermal Shutdown
    6. 8.6 Functional Block Diagram
    7. 8.7 Feature Description
      1. 8.7.1 Power-Save Mode
      2. 8.7.2 Current Limit Operation
      3. 8.7.3 Enable
      4. 8.7.4 Load Disconnect And Reverse Current Protection
    8. 8.8 Device Functional Modes
      1. 8.8.1 Load Disconnect And Reverse Current Protection
      2. 8.8.2 Softstart
      3. 8.8.3 Undervoltage Lockout
      4. 8.8.4 Thermal Regulation
      5. 8.8.5 Thermal Shutdown
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Inductor Selection
          1. 9.2.2.1.1 High-frequency Converter Applications
        2. 9.2.2.2 Output Capacitor
        3. 9.2.2.3 Input Capacitor
        4. 9.2.2.4 Checking Loop Stability
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
    3. 11.3 Thermal Information
  12. 12Package Summary
    1. 12.1 Package Dimensions
  13. 13Device and Documentation Support
    1. 13.1 Device Support
      1. 13.1.1 Third-Party Products Disclaimer
    2. 13.2 Receiving Notification of Documentation Updates
    3. 13.3 Community Resources
    4. 13.4 Trademarks
    5. 13.5 Electrostatic Discharge Caution
    6. 13.6 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

Package Options

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

9.2.2.1 Inductor Selection

A boost converter normally requires two main passive components for storing energy during the conversion, an inductor and an output capacitor are required. It is advisable to select an inductor with a saturation current rating higher than the possible peak current flowing through the power switches.

The inductor peak current varies as a function of the load, the input and output voltages and can be estimated using Equation 4.

Equation 4. TPS61256A eq8_Ilpeak_lvs956.gif

Selecting an inductor with insufficient saturation performance can lead to excessive peak current in the converter. This could eventually harm the device and reduce it's reliability.

When selecting the inductor, as well as the inductance, parameters of importance are: maximum current rating, series resistance, and operating temperature. The inductor DC current rating should be greater (by some margin) than the maximum input average current, refer to Equation 5 and Current Limit Operation section for more details.

Equation 5. TPS61256A eq1_IINDC_lvsag8.gif

The TPS61256A series of step-up converters have been optimized to operate with a effective inductance in the range of 0.7µH to 2.9µH and with output capacitors in the range of 22µF to 47µF. The internal compensation is optimized for an output filter of L = 1µH and CO = 22µF. Larger or smaller inductor values can be used to optimize the performance of the device for specific operating conditions. For more details, see the Checking Loop Stability section.