SLVSGA8B May   2021  – April 2022 TPS25946

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
  7. 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.      15
    8. 7.8 Typical Characteristics
  8. 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 Active Current Limiting
        3. 8.3.3.3 Short-Circuit Protection
      4. 8.3.4 Analog Load Current Monitor
      5. 8.3.5 Reverse Current Protection
      6. 8.3.6 Overtemperature Protection (OTP)
      7. 8.3.7 Fault Response and Indication (FLT)
      8. 8.3.8 Power Good Indication (PG)
      9. 8.3.9 Input Supply Good Indication (SPLYGD)
    4. 8.4 Device Functional Modes
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Single Device, Self-Controlled
    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 Overvoltage Threshold
        3. 9.2.2.3 Setting Output Voltage Rise Time (tR)
        4. 9.2.2.4 Setting Power Good Assertion Threshold
        5. 9.2.2.5 Setting Overcurrent Threshold (ILIM)
        6. 9.2.2.6 Setting Overcurrent Blanking Interval (tITIMER)
        7. 9.2.2.7 Selecting External Bias Resistor (R5)
        8. 9.2.2.8 Selecting External Diode (D1)
      3. 9.2.3 Application Curve
  10. 10Power Supply Recommendations
    1. 10.1 Transient Protection
    2. 10.2 Output Short-Circuit Measurements
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Support Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

9.2.2.2 Setting Overvoltage Threshold

The supply overvoltage threshold is set using the resistors, R1 and R2, whose values can be calculated using Equation 8:

Equation 8. GUID-20210428-CA0I-NXMR-H59D-KTQNHSH4BBSW-low.gif
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) = 14 V. To solve the equation, first choose the value of R1 = 470 kΩ and use the above equation to solve for R2 = 44.06 kΩ.

Using the closest standard 1% resistor values, we get R1 = 470 kΩ, R2 = 44.2 kΩ.