SLVS841G November   2008  – October 2026 TPS2552 , TPS2552-1 , TPS2553 , TPS2553-1

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison Table
  6. 5 Pin Configuration and Functions
  7. 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
  8. 7 Parameter Measurement Information
  9. 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 or EN)
      6. 8.3.6 Thermal Sense
      7. 8.3.7 Quick Output Discharge
    4. 8.4 Device Functional Modes
    5. 8.5 Programming
      1. 8.5.1 Programming the Current-Limit Threshold
  10. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Constant-Current vs Latch-Off Operation and Impact on Output Voltage
    2. 9.2 Typical Applications
      1. 9.2.1 Two-Level Current-Limit Circuit
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedures
          1. 9.2.1.2.1 Designing Above a Minimum Current Limit
          2. 9.2.1.2.2 Designing Below a Maximum Current Limit
          3. 9.2.1.2.3 Accounting for Resistor Tolerance
          4. 9.2.1.2.4 Input and Output Capacitance
        3. 9.2.1.3 Application Curves
      2. 9.2.2 Auto-Retry Functionality
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
      3. 9.2.3 Typical Application as USB Power Switch
        1. 9.2.3.1 Design Requirements
          1. 9.2.3.1.1 USB Power-Distribution Requirements
        2. 9.2.3.2 Detailed Design Procedure
          1. 9.2.3.2.1 Universal Serial Bus (USB) Power-Distribution Requirements
    3. 9.3 Power Supply Recommendations
      1. 9.3.1 Self-Powered and Bus-Powered Hubs
      2. 9.3.2 Low-Power Bus-Powered and High-Power Bus-Powered Functions
      3. 9.3.3 Power Dissipation and Junction Temperature
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
      2. 9.4.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Device Support
    2. 10.2 Receiving Notification of Documentation Updates
    3. 10.3 Support Resources
    4. 10.4 Trademarks
    5. 10.5 Electrostatic Discharge Caution
    6. 10.6 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information

8.5.1 Programming the Current-Limit Threshold

The overcurrent threshold is user programmable through an external resistor. The TPS255x and TPS255x-1 use an internal regulation loop to provide a regulated voltage on the ILIM pin. The current-limit threshold is proportional to the current sourced out of ILIM. The recommended 1% resistor range for RILIM is from 15kΩ ≤ RILIM ≤ 232kΩ to confirm stability of the internal regulation loop. TPS25530-1 supports a resistor range of 10kΩ ≤ RILIM ≤ 232kΩ. Many applications require that the minimum current limit is above a certain current level or that the maximum current limit is 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 and Figure 8-1 can be used to calculate the resulting overcurrent threshold for a given external resistor value (RILIM). Figure 8-1 includes current-limit tolerance due to variations caused by temperature and process. However, the equations do not account for tolerance due to external resistor variation, so it is important to account for this tolerance when selecting RILIM. The traces routing the RILIM resistor to the TPS255x and TPS255x-1 must be as short as possible to reduce parasitic effects on the current-limit accuracy.

RILIM can be selected to provide a current-limit threshold that occurs 1) above a minimum load current or 2) below a maximum load current.

To design above a minimum current-limit threshold, find the intersection of RILIM and the maximum desired load current on the IOS(min) curve and select a value of RILIM below this value. Programming the current limit above a minimum threshold is important to confirm start-up into full load or heavy capacitive loads. The resulting maximum current-limit threshold is the intersection of the selected value of RILIM and the IOS(max) curve.

To design below a maximum current-limit threshold, find the intersection of RILIM and the maximum desired load current on the IOS(max) curve and select a value of RILIM above this value. Programming the current limit below a maximum threshold is important to avoid current limiting upstream power supplies, causing the input voltage bus to droop. The resulting minimum current-limit threshold is the intersection of the selected value of RILIM and the IOS(min) curve.

Current-limit threshold equations (IOS):

Equation 1. I O S m a x ( m A ) = 22980 V R I L I M 0.94 k Ω
Equation 2. IOSnom(mA)=23950VRILIM0.977kΩ
Equation 3. IOSmin(mA)=25230VRILIM1.016kΩ

where

  • 15kΩ ≤ RILIM ≤ 232kΩ

While the maximum recommended value of RILIM is 232kΩ, there is one additional configuration that allows for a lower current-limit threshold. The ILIM pin can connect directly to IN to provide a 75mA (typical) current-limit threshold. Additional low-ESR ceramic capacitance can be necessary from IN to GND in this configuration to prevent unwanted noise from coupling into the sensitive ILIM circuitry. The equations above the graph below do not consider the exclusive 10kΩ setting in the TPS25530-1. Use the electrical characteristic parameters for 10kΩ when designing with TPS25530-1.

TPS2552 TPS2552-1 TPS2553 TPS2553-1 Current-Limit Threshold vs RILIMFigure 8-1 Current-Limit Threshold vs RILIM