JAJSOA3B February   2023  – June 2024 TPS25948

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 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 Timing Requirements
    7. 6.7 Switching Characteristics
    8. 6.8 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 Undervoltage Lockout (UVLO and UVP)
      2. 7.3.2 Overvoltage Lockout (OVLO)
      3. 7.3.3 Inrush Current, Overcurrent, and Short Circuit Protection
        1. 7.3.3.1 Slew Rate (dVdt) and Inrush Current Control
        2. 7.3.3.2 Active Current Limiting
        3. 7.3.3.3 Short-Circuit Protection
      4. 7.3.4 Analog Load Current Monitor
      5. 7.3.5 Reverse Current Protection
      6. 7.3.6 Overtemperature Protection (OTP)
      7. 7.3.7 Fault Response and Indication (FLT)
      8. 7.3.8 Supply Good Indication (SPLYGD/SPLYGD)
    4. 7.4 Device Functional Modes
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Single Device, Self-Controlled
    3. 8.3 Typical Application
      1. 8.3.1 Design Requirements
      2. 8.3.2 Detailed Design Procedure
        1. 8.3.2.1 Setting Overvoltage Threshold
        2. 8.3.2.2 Setting Output Voltage Rise Time (tR)
        3. 8.3.2.3 Setting Overcurrent Threshold (ILIM)
        4. 8.3.2.4 Setting Overcurrent Blanking Interval (tITIMER)
      3. 8.3.3 Application Curves
    4. 8.4 Active ORing
    5. 8.5 Priority Power MUXing
    6. 8.6 Parallel Operation
    7. 8.7 USB PD Port Protection
    8. 8.8 Power Supply Recommendations
      1. 8.8.1 Transient Protection
      2. 8.8.2 Output Short-Circuit Measurements
    9. 8.9 Layout
      1. 8.9.1 Layout Guidelines
      2. 8.9.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Documentation Support
      1. 9.1.1 Related Documentation
    2. 9.2 ドキュメントの更新通知を受け取る方法
    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

8.3.2.1 Setting Overvoltage Threshold

The supply overvoltage threshold is set using the resistors, R1 and R2, whose values can be calculated as:
Equation 8. VIN(OV)=VOV(R) x (R1 + R2)R2 
Where VOV(R) is the OVLO rising threshold. Because R1, R2 leak the current from input supply VIN, these resistors must be selected based on the acceptable leakage current from input power supply VIN. The current drawn by R1, R2 from the power supply is IR12 = VIN / (R1 + R2). However, leakage currents due to external active components connected to the resistor string can add error to these calculations. So, the resistor string current, IR12, must be chosen to be 20 times greater than the leakage current expected on the OVLO pin.

From the device electrical specifications, OVLO leakage current is 0.1 μA (maximum), VOV(R) = 1.2 V. From design requirements, VIN(OV) = 22 V. To solve the equation, first choose the value of R1 = 470 kΩ and use the above equation to solve for R2 = 27.11 kΩ.

Using the closest standard 1% resistor values, we get R1 = 470 kΩ, R2 = 26.7 kΩ.