SLVSFR1 August   2020 TPS25980

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
    1.     7
  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
    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 Protection (UVLO and UVP)
      2. 8.3.2 Overvoltage Protection (OVP)
      3. 8.3.3 Inrush Current, Overcurrent, and Short-Circuit Protection
        1. 8.3.3.1 Slew Rate and Inrush Current Control (dVdt)
        2. 8.3.3.2 Circuit Breaker
        3. 8.3.3.3 Short-Circuit Protection
      4. 8.3.4 Overtemperature Protection (OTP)
      5. 8.3.5 Analog Load Current Monitor (IMON)
      6. 8.3.6 Power Good (PG)
      7. 8.3.7 Load Detect/Handshake (LDSTRT)
    4. 8.4 Fault Response
    5. 8.5 Device Functional Modes
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application: Patient Monitoring System in Medical Applications
      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 the Current Limit Threshold: RILIM Selection
        3. 9.2.2.3 Setting the Undervoltage Lockout Set Point
        4. 9.2.2.4 Choosing the Current Monitoring Resistor: RIMON
        5. 9.2.2.5 Setting the Output Voltage Ramp Time (TdVdt)
          1. 9.2.2.5.1 Case 1: Start-Up Without Load: Only Output Capacitance COUT Draws Current
          2. 9.2.2.5.2 Case 2: Start-Up With Load: Output Capacitance COUT and Load Draw Current
        6. 9.2.2.6 Setting the Load Handshake (LDSTRT) Delay
        7. 9.2.2.7 Setting the Transient Overcurrent Blanking Interval (tITIMER)
        8. 9.2.2.8 Setting the Auto-Retry Delay and Number of Retries
      3. 9.2.3 Application Curves
    3. 9.3 System Examples
      1. 9.3.1 Optical Module Power Rail Path Protection
        1. 9.3.1.1 Design Requirements
        2. 9.3.1.2 Device Selection
        3. 9.3.1.3 External Component Settings
        4. 9.3.1.4 Voltage Drop
        5. 9.3.1.5 Application Curves
      2. 9.3.2 Input Protection for 12-V Rail Applications: PCIe Cards, Storage Interfaces and DC Fans
  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
        1. 12.1.1.1 Related Links
    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

9.2.2.3 Setting the Undervoltage Lockout Set Point

The undervoltage lockout (UVLO) trip point is adjusted using the external voltage divider network of RVL1 and RVL2 connected between IN, EN/UVLO and GND pins of the device. The resistor values required for setting the undervoltage are calculated using Equation 11.

Equation 11. GUID-21AE15B6-43B9-410A-8FB4-7FBEA15CABF9-low.gif

For minimizing the input current drawn from the power supply, TI recommends to use higher values of resistance for RVL1 and RVL2. However, leakage currents due to external active components connected to the resistor string can add error to these calculations. So, the resistor string current, IRVL12 must be 20 times greater than the leakage current (IENLKG).

From the device electrical specifications, UVLO rising threshold VUVLO(R) = 1.2 V. From design requirements, VINUVLO = 10.8 V. First choose the value of RVL1 = 1 MΩ and use Equation 11 to calculate RVL2 = 125 kΩ.

Use the closest standard 1% resistor values: RVL1 = 1 MΩ, and RVL2 = 125 kΩ