ZHCSOF9B april   2022  – june 2023 TPS25981

PRODUCTION DATA  

  1.   1
  2. 1 特性
  3. 2 应用
  4. 3 说明
  5. 4 Revision History
  6. 5 Device Comparison Table
  7. 6 Pin Configuration and Functions
  8. 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 Switching Characteristics
      1.      16
    8. 7.8 Typical Characteristics
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Undervoltage Lockout (UVLO and UVP)
      2. 8.3.2 Overvoltage Lockout (OVLO)
      3. 8.3.3 Inrush Current, Overcurrent, and Short-Circuit Protection
        1. 8.3.3.1 Slew Rate (dVdt) and Inrush Current Control
        2. 8.3.3.2 Circuit-Breaker During Steady-State
        3. 8.3.3.3 Active Current Limiting During Start-Up
        4. 8.3.3.4 Short-Circuit Protection
      4. 8.3.4 Analog Load Current Monitor
      5. 8.3.5 Overtemperature Protection (OTP)
      6. 8.3.6 Fault Response and Indication (FLT)
      7. 8.3.7 Power Good Indication (PG)
      8. 8.3.8 Quick Output Discharge (QOD)
      9. 8.3.9 Reverse Current Blocking FET Driver
    4. 8.4 Device Functional Modes
  10. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Single Device, Self-Controlled
      2. 9.1.2 Parallel Operation
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Device Selection
        2. 9.2.2.2 Setting Output Voltage Rise Time (tR)
        3. 9.2.2.3 Setting Overcurrent Threshold (ILIM)
        4. 9.2.2.4 Setting Overcurrent Blanking Interval (tITIMER)
        5. 9.2.2.5 Voltage Drop
      3. 9.2.3 Application Curves
  11. 10Power Supply Recommendations
    1. 10.1 Transient Protection
    2. 10.2 Output Short-Circuit Measurements
  12. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  13. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
    2. 12.2 接收文档更新通知
    3. 12.3 支持资源
    4. 12.4 Trademarks
    5. 12.5 静电放电警告
    6. 12.6 术语表
  14. 13Mechanical, Packaging, and Orderable Information

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10.1 Transient Protection

In the case of a short-circuit and overload current limit when the device interrupts current flow, the input inductance generates a positive voltage spike on the input, and the output inductance generates a negative voltage spike on the output. The peak amplitude of voltage spikes (transients) is dependent on the value of inductance in series to the input or output of the device. Such transients can exceed the absolute maximum ratings of the device if steps are not taken to address the issue. Typical methods for addressing transients include:

  • Minimize lead length and inductance into and out of the device.
  • Use a large PCB GND plane.
  • Connect a Schottky diode from the OUT pin ground to absorb negative spikes.
  • Connect a low ESR capacitor larger than 1 μF at the OUT pin very close to the device.
  • Use a low-value ceramic capacitor CIN = 1 μF to absorb the energy and dampen the transients. The capacitor voltage rating must be at least twice the input supply voltage to be able to withstand the positive voltage excursion during inductive ringing.

    Use Equation 15 to estimate the approximate value of input capacitance:

    Equation 15. V S P I K E A b s o l u t e   =   V I N +   I L O A D     ×   L I N C I N

    where

    • VIN is the nominal supply voltage.
    • ILOAD is the load current.
    • LIN equals the effective inductance seen looking into the source.
    • CIN is the capacitance present at the input.
  • Some applications can require the addition of a Transient Voltage Suppressor (TVS) to prevent transients from exceeding the absolute maximum ratings of the device. In some cases, even if the maximum amplitude of the transients is below the absolute maximum rating of the device, a TVS can help to absorb the excessive energy dump and prevent it from creating very fast transient voltages on the input supply pin of the IC, which can couple to the internal control circuits and cause unexpected behavior.

Figure 10-1 shows the circuit implementation with optional protection components.

GUID-20220319-SS0I-FFT6-1HJK-MNK1Q88M1P8F-low.gif Figure 10-1 Circuit Implementation with Optional Protection Components