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

8.3.1 Overcurrent Conditions

The TPS2556-Q1 and TPS2557-Q1 devices respond to overcurrent conditions by limiting their output current to IOS. On detecting an overcurrent condition, the device maintains a constant output current, and the output voltage reduces accordingly. Two possible overload conditions can occur.

The first condition is when a short circuit or partial short circuit is present on a powered-up and enabled device. With the output voltage held near zero potential with respect to ground, the TPS2556-Q1 or TPS2557-Q1 device ramps the output current to IOS. The TPS2556-Q1 and TPS2557-Q1 devices limit the current to IOS until removal of the overload condition or until the device begins to cycle thermally.

The second condition is when a short circuit, partial short circuit, or transient overload occurs while the device is enabled and powered on. The device responds to the overcurrent condition within time t(IOS) (see Figure 8-2). Overdriving the current-sense amplifier during this time and momentarily disables the internal N-channel MOSFET. The current-sense amplifier recovers and ramps the output current to IOS. Similar to the previous case, the TPS2556-Q1 and TPS2557-Q1 devices limit the current to IOS until removal of the overload condition or until the device begins to cycle thermally.

The TPS2556-Q1 and TPS2557-Q1 cycle thermally if an overload condition is present long enough to activate thermal limiting in any of the above cases. The device turns off when the junction temperature exceeds 135°C (minimum) while in current limit. The device remains off until the junction temperature cools 20°C (typical) and then restarts. The TPS2556-Q1 and TPS2557-Q1 cycle on and off until removal of the overload (see Figure 9-7).