SLUSDN8 March   2021 TPS62865 , TPS62867

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Options
  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 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 Power Save Mode
      2. 8.3.2 Forced PWM Mode
      3. 8.3.3 100% Duty Cycle Mode Operation
      4. 8.3.4 Soft Start
      5. 8.3.5 Switch Current Limit and HICCUP Short-Circuit Protection
      6. 8.3.6 Undervoltage Lockout
      7. 8.3.7 Thermal Shutdown
    4. 8.4 Device Functional Modes
      1. 8.4.1 Enable and Disable (EN)
      2. 8.4.2 Power Good (PG)
      3. 8.4.3 Voltage Setting and Mode Selection (VSET/MODE)
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Custom Design With WEBENCH® Tools
        2. 9.2.2.2 Setting The Output Voltage
        3. 9.2.2.3 Output Filter Design
        4. 9.2.2.4 Inductor Selection
        5. 9.2.2.5 Capacitor Selection
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
      1. 11.2.1 Thermal Considerations
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Third-Party Products Disclaimer
      2. 12.1.2 Development Support
        1. 12.1.2.1 Custom Design With WEBENCH® Tools
    2. 12.2 Documentation Support
      1. 12.2.1 Related Documentation
    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

8.3.3 100% Duty Cycle Mode Operation

There is no limitation for small duty cycles since even at very low duty cycles, the switching frequency is reduced as needed to always ensure a proper regulation.

If the output voltage level comes close to the input voltage, the device enters 100% mode. While the high-side switch is constantly turned on, the low-side switch is switched off. The difference between VIN and VOUT is determined by the voltage drop across the high-side MOSFET and the DC resistance of the inductor. The minimum VIN that is needed to maintain a specific VOUT value is estimated as:

Equation 2.
GUID-07B23BB8-73C0-4D18-B4AF-DBD98380BF2D-low.svg

where

  • VIN,MIN is the minimum input voltage to maintain an output voltage
  • IOUT,MAX is the maximum output current
  • RDS(on) is the high-side FET ON-resistance
  • RL is the inductor ohmic resistance (DCR)