ZHCSQ69B june   2022  – august 2023 TPS7A15

PRODUCTION DATA  

  1.   1
  2. 1 特性
  3. 2 应用
  4. 3 说明
  5. 4 Revision History
  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 Switching Characteristics
    7. 6.7 Typical Characteristics
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Excellent Transient Response
      2. 7.3.2 Active Overshoot Pulldown Circuitry
      3. 7.3.3 Global Undervoltage Lockout (UVLO)
      4. 7.3.4 Enable Input
      5. 7.3.5 Internal Foldback Current Limit
      6. 7.3.6 Active Discharge
      7. 7.3.7 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Normal Mode
      2. 7.4.2 Dropout Mode
      3. 7.4.3 Disabled Mode
  9. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1  Recommended Capacitor Types
      2. 8.1.2  Input, Output, and Bias Capacitor Requirements
      3. 8.1.3  Dropout Voltage
      4. 8.1.4  Behavior During Transition From Dropout Into Regulation
      5. 8.1.5  Device Enable Sequencing Requirement
      6. 8.1.6  Load Transient Response
      7. 8.1.7  Undervoltage Lockout Circuit Operation
      8. 8.1.8  Power Dissipation (PD)
      9. 8.1.9  Estimating Junction Temperature
      10. 8.1.10 Recommended Area for Continuous Operation
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curve
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Examples
  10. 9 Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 Development Support
        1. 9.1.1.1 Evaluation Module
      2. 9.1.2 Device Nomenclature
    2. 9.2 Documentation Support
      1. 9.2.1 Related Documentation
    3. 9.3 接收文档更新通知
    4. 9.4 支持资源
    5. 9.5 Trademarks
    6. 9.6 静电放电警告
    7. 9.7 术语表
  11. 10Mechanical, Packaging, and Orderable Information
    1. 10.1 Mechanical Data

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7.3.5 Internal Foldback Current Limit

The device has an internal current limit circuit that protects the regulator during transient high-load current faults or shorting events. The current limit is a hybrid brick-wall foldback scheme. The current limit transitions from a brick-wall scheme to a foldback scheme at the foldback voltage (VFOLDBACK).

In a high-load current fault with the output voltage above VFOLDBACK, the brick-wall scheme limits the output current to the current limit (ICL). When the voltage drops below VFOLDBACK, a foldback current limit activates that scales back the current as the output voltage approaches GND. When the output is shorted to GND, the device supplies a typical current called the short-circuit current limit (ISC). ICL and ISC are listed in the Electrical Characteristics table.

For this device, VFOLDBACK = 60% × VOUT(nom).

The output voltage is not regulated when the device is in current limit. When a current limit event occurs, the device begins to heat up because of the increase in power dissipation. When the device is in brick-wall current limit, the pass transistor dissipates power [(VIN – VOUT) × ICL]. When the device output is shorted and the output is below VFOLDBACK, the pass transistor dissipates power [(VIN – VOUT) × ISC]. If thermal shutdown is triggered, the device turns off. After the device cools down, the internal thermal shutdown circuit turns the device back on. If the output current fault condition continues, the device cycles between current limit and thermal shutdown. For more information on current limits, see the Know Your Limits application note.

Figure 7-2 shows a diagram of the foldback current limit.

GUID-40F8D0B5-7213-49B1-BD3C-4DBF8791BD85-low.gifFigure 7-2 Foldback Current Limit