ZHCSF29E May   2016  – January 2021 TPS25940-Q1

PRODMIX  

  1. 1 特性
  2. 2 应用
  3. 3 说明
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Timing Requirements
    7. 7.7 Typical Characteristics
  8. 8 Parametric Measurement Information
  9. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1 Enable and Adjusting Undervoltage Lockout
      2. 9.3.2 Overvoltage Protection (OVP)
      3. 9.3.3 Hot Plug-In and In-Rush Current Control
      4. 9.3.4 Overload and Short Circuit Protection
        1. 9.3.4.1 Overload Protection
        2. 9.3.4.2 Short Circuit Protection
        3. 9.3.4.3 Start-Up with Short on Output
        4. 9.3.4.4 Constant Current Limit Behavior During Overcurrent Faults
      5. 9.3.5 FAULT Response
      6. 9.3.6 Current Monitoring
      7. 9.3.7 Power Good Comparator
      8. 9.3.8 IN, OUT and GND Pins
      9. 9.3.9 Thermal Shutdown
    4. 9.4 Device Functional Modes
      1. 9.4.1 DevSleep Mode
      2. 9.4.2 Shutdown Control
  10. 10Application and Implementation
    1. 10.1 Application Information
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
        1. 10.2.2.1 Step by Step Design Procedure
        2. 10.2.2.2 Programming the Current-Limit Threshold: R(ILIM) Selection
        3. 10.2.2.3 Undervoltage Lockout and Overvoltage Set Point
        4. 10.2.2.4 Programming Current Monitoring Resistor—RIMON
        5. 10.2.2.5 Setting Output Voltage Ramp Time (tdVdT)
          1. 10.2.2.5.1 Case1: Start-Up Without Load: Only Output Capacitance C(OUT) Draws Current During Start-Up
          2. 10.2.2.5.2 Case 2: Start-Up With Load: Output Capacitance C(OUT) and Load Draws Current During Start-Up
        6. 10.2.2.6 Programing the Power Good Set Point
        7. 10.2.2.7 Support Component Selections—R6, R7 and CIN
      3. 10.2.3 Application Curves
      4. 10.2.4 System Examples
        1. 10.2.4.1 VBUS Short-to-Battery, Short-to-Ground Protection of USB Port in Automotive Systems
        2. 10.2.4.2 Power Failure Protection for Holdup Power
        3. 10.2.4.3 Overload Detection Using TPS25940xx-Q1
  11. 11Power Supply Recommendations
    1. 11.1 Transient Protection
    2. 11.2 Output Short-Circuit Measurements
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
  13. 13Device and Documentation Support
    1. 13.1 Documentation Support
      1. 13.1.1 Related Documentation
    2. 13.2 支持资源
    3. 13.3 Trademarks
    4. 13.4 静电放电警告
    5. 13.5 术语表
  14. 14Mechanical, Packaging, and Orderable Information

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10.2.4.3 Overload Detection Using TPS25940xx-Q1

The TPS25940xx-Q1 device has enhanced features such as load current monitoring output IMON and an integrated power good comparator for voltage monitoring. These two functional blocks can be utilized as per circuit configuration shown in Figure 10-27, to FLAG the overload event.

GUID-F32783B5-1945-4402-9CBA-F62F811EAAF0-low.gifFigure 10-27 Circuit Configuration for Overload Detection Using TPS25940xx-Q1

The output voltage at IMON terminal VIMON can be used as a means of monitoring current flow through the system and its value can be calculated from Equation 6.

The power good comparator of TPS25940xx-Q1 has an internal reference of VPGTHR = 0.99 V at the negative terminal and the positive terminal PGTH can be utilized for monitoring voltage of any specific rail. As shown in the Figure 10-27, the output voltage at IMON terminal (VIMON) is fed to the positive terminal PGTH (VPGTH) of the comparator. When the PGTH pin voltage (VPGTH = VIMON) is higher than the internal reference VPGTHR, the open-drain comparator output PGOOD asserts HIGH to indicate overload event.

For example, to detect overcurrent event at load current IOUT of 300 mA, the value of RIMON can be calculated using Equation 35.

Equation 35. GUID-F97525E1-EB69-4246-991C-2B41277FE906-low.gif
Equation 36. GUID-BD0020D9-2259-41BF-8620-198815AA40ED-low.gif

A close value of 61.9 kΩ is chosen for RIMON.

Figure 10-28 shows the overload flag status when the load is changed from 150 mA to 600 mA and back. As seen in the Figure 10-28, the overload status (OL_Status) becomes active HIGH when the load current crosses 300 mA.

GUID-42831970-BDDB-4659-B20D-65B6E66B603B-low.gifFigure 10-28 Overload Flag Status for Change in Load from 150 mA to 600 mA and Back