SLVSC97B March   2014  – September 2020 TPS2556-Q1 , TPS2557-Q1

PRODUCTION DATA  

  1. 1 Features
  2. 2 Application
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Terminal Configuration and Functions
    1.     Terminal Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 Handling Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Switching Characteristics
    7. 7.7 Typical Characteristics
      1.      16
        1.       Parameter Measurement Information
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Overcurrent Conditions
      2. 8.3.2 FAULT Response
      3. 8.3.3 Thermal Sense
    4. 8.4 Device Functional Modes
      1. 8.4.1 Undervoltage Lockout (UVLO)
      2. 8.4.2 Enable ( EN OR EN)
      3. 8.4.3 Auto-Retry Functionality
      4. 8.4.4 Two-Level Current-Limit Circuit
  9. 9 Applications and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application, Design for Current Limit
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Determine Design Parameters
        2. 9.2.2.2 Programming the Current-Limit Threshold
        3. 9.2.2.3 Selecting Current-Limit Resistor 1
        4. 9.2.2.4 Selecting Current-Limit Resistor 2
        5. 9.2.2.5 Accounting for Resistor Tolerance
        6. 9.2.2.6 Power Dissipation and Junction Temperature
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Related Links
    2. 12.2 Trademarks
    3. 12.3 Electrostatic Discharge Caution
    4. 12.4 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

9.2.2.2 Programming the Current-Limit Threshold

The overcurrent threshold is user-programmable via an external resistor. The TPS2556-Q1 and TPS2557-Q1 devices use an internal regulation loop to provide a regulated voltage on the ILIM terminal. The current-limit threshold is proportional to the current sourced out of ILIM. The recommended 1% resistor range for RILIM is 20 kΩ ≤ R(ILIM) ≤ 187 kΩ to ensure stability of the internal regulation loop. Many applications require that the minimum current limit be above a certain current level or that the maximum current limit be below a certain current level, so it is important to consider the tolerance of the overcurrent threshold when selecting a value for RILIM. The following equations approximate the resulting overcurrent threshold for a given value of external resistor RILIM. Consult the Electrical Characteristics table for specific current-limit settings. The traces routing the RILIM resistor to the TPS2556-Q1 and TPS2557-Q1 devices should be as short as possible to reduce parasitic effects on the current-limit accuracy.

Equation 1. GUID-CCB614F8-8DE5-4085-92CD-76A471F72B50-low.gif
GUID-9E2EFDE2-24A3-43F8-91B8-080E24C0EF62-low.pngFigure 9-2 Current-Limit Threshold versus R(ILIM)