JAJSF46I March   2018  – March 2024 TPS62824 , TPS62824A , TPS62825 , TPS62825A , TPS62826 , TPS62826A , TPS62827 , TPS62827A

PRODUCTION DATA  

  1.   1
  2. 1 特長
  3. 2 アプリケーション
  4. 3 概要
  5. 4 Device Options
  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 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Pulse Width Modulation (PWM) Operation
      2. 7.3.2 Power Save Mode (PSM) Operation
      3. 7.3.3 Minimum Duty Cycle and 100% Mode Operation
      4. 7.3.4 Soft Start
      5. 7.3.5 Switch Current Limit and HICCUP Short-Circuit Protection
      6. 7.3.6 Undervoltage Lockout
      7. 7.3.7 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Enable, Disable, and Output Discharge
      2. 7.4.2 Power Good
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Custom Design With WEBENCH® Tools
        2. 8.2.2.2 Setting The Output Voltage
        3. 8.2.2.3 Output Filter Design
        4. 8.2.2.4 Inductor Selection
        5. 8.2.2.5 Capacitor Selection
      3. 8.2.3 Application Curves
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
        1. 8.4.2.1 Thermal Considerations
  10. 9 Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 サード・パーティ製品に関する免責事項
      2. 9.1.2 Development Support
        1. 9.1.2.1 Custom Design With WEBENCH® Tools
    2. 9.2 Documentation Support
      1. 9.2.1 Related Documentation
    3. 9.3 サポート・リソース
    4. 9.4 Trademarks
    5. 9.5 静電気放電に関する注意事項
    6. 9.6 用語集
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

7.3.5 Switch Current Limit and HICCUP Short-Circuit Protection

The switch current limit prevents the device from drawing excessive current in case of externally-caused overcurrent or short-circuit condition. Due to an internal propagation delay (typically 60ns), the actual AC peak current can exceed the static current limit during that time.

If the current limit threshold is reached, the device delivers maximum output current. Detecting this condition for 32 switching cycles (about 13μs), the device turns off the high-side MOSFET for about 100μs which allows the inductor current to decrease through the low-side MOSFET body diode and then restarts again with a soft start cycle. As long as the overload condition is present, the device hiccups that way, limiting the output power.

In forced PWM devices, a negative current limit (ILIMN) is enabled to prevent excessive current flowing backwards to the input. When the inductor current reaches ILIMN, the low-side MOSFET turns off and the high-side MOSFET turns on and kept on until TON time expires.