SLVSE31C January   2018  – July 2018 TPSM84209

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified Application
      2.      Efficiency vs Output Current
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin 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 Typical Characteristics (VIN = 5 V)
    7. 6.7 Typical Characteristics (VIN = 12 V)
    8. 6.8 Typical Characteristics (VIN = 24 V)
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Adjusting the Output Voltage
      2. 7.3.2  Input Capacitor Selection
      3. 7.3.3  Undervoltage Lockout (UVLO)
      4. 7.3.4  Output Capacitor Selection
      5. 7.3.5  Feed-Forward Capacitor
      6. 7.3.6  Operating Range
      7. 7.3.7  Output Current Rating
      8. 7.3.8  Enable (EN)
      9. 7.3.9  Internal Soft Start
      10. 7.3.10 Safe Start-Up Into Prebiased Outputs
      11. 7.3.11 Light Load Efficiency / Eco-Mode
      12. 7.3.12 Voltage Dropout
      13. 7.3.13 Overcurrent Protection
      14. 7.3.14 Output Overvoltage Protection (OVP)
      15. 7.3.15 Thermal Performance
      16. 7.3.16 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Active Mode
      2. 7.4.2 Eco-Mode Operation
      3. 7.4.3 Shutdown Mode
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Custom Design With WEBENCH® Tools
        2. 8.2.2.2 Output Voltage Setpoint
        3. 8.2.2.3 Input Capacitors
        4. 8.2.2.4 Output Capacitors
        5. 8.2.2.5 Enable Control
      3. 8.2.3 Application Waveforms
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Examples
    3. 10.3 EMI
      1. 10.3.1 EMI Plots
    4. 10.4 Package Specifications
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
    2. 11.2 Custom Design With WEBENCH® Tools
    3. 11.3 Receiving Notification of Documentation Updates
    4. 11.4 Community Resources
    5. 11.5 Trademarks
    6. 11.6 Electrostatic Discharge Caution
    7. 11.7 Glossary
  12. 12Mechanical, Packaging, and Orderable Information
    1. 12.1 Tape and Reel Information

7.3.3 Undervoltage Lockout (UVLO)

The TPSM84209 device has an internal UVLO circuit which prevents the device from operating until the VIN voltage exceeds the UVLO rising threshold, (4.1 V (typical)). The device is disabled when the VIN pin voltage falls below the internal VIN UVLO threshold. The internal VIN UVLO threshold has a hysteresis of 500 mV.

Applications may require a higher UVLO threshold to prevent early turnon, for sequencing requirements or to prevent input current draw at lower input voltages. An external resistor divider can be added to the EN pin to adjust the UVLO threshold higher. The external resistor divider can be configured as shown in Figure 18. Table 3 lists standard values for RUVLO1 and RUVLO2 to adjust the UVLO voltage higher.

TPSM84209 CheapTrickUVLO.gifFigure 18. Adjustable UVLO

Table 3. Standard Resistor Values for Adjusting UVLO

VIN UVLO (V) 4.5 10 15 18 20
RUVLO1 (kΩ) 68.1 68.1 68.1 68.1 68.1
RUVLO2 (kΩ) 25.5 9.53 6.04 4.99 4.42