ZHCSQA4A April   2022  – July 2022 TPS22811

PRODUCTION DATA  

  1. 1 特性
  2. 2 应用
  3. 3 说明
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 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
      1.      14
    8. 6.8 Typical Characteristics
  7. 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 Short-Circuit Protection
        3. 7.3.3.3 Active Current Limiting During Start-Up
      4. 7.3.4 Analog Load Current Monitor
      5. 7.3.5 Overtemperature Protection (OTP)
      6. 7.3.6 Fault Response
      7. 7.3.7 Power-Good Indication (PG)
      8. 7.3.8 Quick Output Discharge (QOD)
    4. 7.4 Device Functional Modes
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Single Device, Self-Controlled
      2. 8.1.2 Parallel Operation
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Setting Undervoltage and Overvoltage Thresholds
        2. 8.2.2.2 Setting Output Voltage Rise Time (tR)
        3. 8.2.2.3 Setting Power-Good Assertion Threshold
        4. 8.2.2.4 Setting Analog Current Monitor Voltage (IMON) Range
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
    1. 9.1 Transient Protection
    2. 9.2 Output Short-Circuit Measurements
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 接收文档更新通知
    3. 11.3 支持资源
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 术语表
  12. 12Mechanical, Packaging, and Orderable Information

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8.2.2.3 Setting Power-Good Assertion Threshold

The power-good assertion threshold can be set using the resistors R4 and R5 connected to the PGTH pin whose values can be calculated as:

Equation 13. VPG =VPGTH(R) × (R4+ R5)R5

Because R4 and R5 leak the current from the output rail VOUT, these resistors must be selected to minimize the leakage current. The current drawn by R4 and R5 from the power supply is IR45 = VOUT / (R4 + R5). However, leakage currents due to external active components connected to the resistor string can add error to these calculations. So, the resistor string current, IR123 must be chosen to be 20 times greater than the PGTH leakage current expected. From the device electrical specifications, PGTH leakage current is 1 μA (maximum), VPGTH(R) = 1.2 V and from design requirements, VPG = 11.4 V. To solve the equation, first choose the value of R4 = 47 kΩ and calculate R5 = 5.52 kΩ. Choose nearest 1% standard resistor value as R5 = 5.6 kΩ.