SLVSBD0B November   2012  – June 2020 TPS2553-Q1

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Typical Application as USB Power Switch
  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 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Overcurrent Conditions
      2. 8.3.2 Reverse-Voltage Protection
      3. 8.3.3 FAULT Response
      4. 8.3.4 Undervoltage Lockout (UVLO)
      5. 8.3.5 Enable (EN)
      6. 8.3.6 Thermal Sense
    4. 8.4 Device Functional Modes
    5. 8.5 Programming
      1. 8.5.1 Programming the Current-Limit Threshold
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Constant-Current and Impact on Output Voltage
      2. 9.1.2 Accounting for Resistor Tolerance
      3. 9.1.3 Input and Output Capacitance
    2. 9.2 Typical Applications
      1. 9.2.1 Application 1: Designing Above a Minimum Current-Limit
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
        3. 9.2.1.3 Application Curves
      2. 9.2.2 Application 2: Designing Below a Maximum Current-Limit
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
      3. 9.2.3 Application 3: Auto-Retry Functionality
        1. 9.2.3.1 Design Requirements
        2. 9.2.3.2 Detailed Design Procedure
      4. 9.2.4 Application 4: Two-Level Current-Limit Circuit
        1. 9.2.4.1 Design Requirements
        2. 9.2.4.2 Detailed Design Procedure
      5. 9.2.5 Application 5: Typical Application as USB Power Switch
        1. 9.2.5.1 Design Requirements
        2. 9.2.5.2 Detailed Design Procedure
          1. 9.2.5.2.1 Universal Serial Bus (USB) Power-Distribution Requirements
  10. 10Power Supply Recommendations
    1. 10.1 USB Self-Powered (SPH) and Bus-Powered (BPH) Hubs
    2. 10.2 USB Low-Power Bus-Powered and High-Power Bus-Powered Functions
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
    3. 11.3 Power Dissipation and Junction Temperature
  12. 12Device and Documentation Support
    1. 12.1 Device Support
    2. 12.2 Support Resource
    3. 12.3 Trademarks
    4. 12.4 Electrostatic Discharge Caution
    5. 12.5 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

9.1.1 Constant-Current and Impact on Output Voltage

During normal operation the constant-current device (TPS2553-Q1) has a load current that is less than the current-limit threshold and the device is not limiting current. During normal operation the N-channel MOSFET is fully enhanced, and VOUT = VIN – (IOUT × rDS(on)). The voltage drop across the MOSFET is relatively small compared to VIN, and VOUT ≈ VIN.

During the initial onset of an overcurrent event, the constant-current device (TPS2553-Q1) limits current to the programmed current-limit threshold set by RILIM by operating the N-channel MOSFET in the linear mode. During current-limit operation, the N-channel MOSFET is no longer fully-enhanced and the resistance of the device increases. This allows the device to effectively regulate the current to the current-limit threshold. The effect of increasing the resistance of the MOSFET is that the voltage drop across the device is no longer negligible (VIN ≠ VOUT), and VOUT decreases. The amount that VOUT decreases is proportional to the magnitude of the overload condition. The expected VOUT can be calculated by IOS × RLOAD, where IOS is the current-limit threshold and RLOAD is the magnitude of the overload condition. For example, if IOS is programmed to 1-A and a 1-Ω overload condition is applied, the resulting VOUT is 1 V.

The constant-current device (TPS2553-Q1) operates during the initial onset of an overcurrent event, if the overcurrent event lasts longer than the internal delay deglitch circuit (7.5-ms typical). The constant-current device (TPS2553-Q1) asserts the FAULT flag after the deglitch period and continues to regulate the current to the current-limit threshold indefinitely. In practical circuits, the power dissipation in the package will increase the die temperature above the overtemperature shutdown threshold (135°C minimum), and the device will turn off until the die temperature decreases by the hysteresis of the thermal shutdown circuit (10°C typical). The device will turn on and continue to thermal cycle until the overload condition is removed. The constant-current devices resume normal operation once the overload condition is removed.