SLVSGM1B July   2023  – June 2024 TPSM828301 , TPSM828302 , TPSM828303

PRODMIX  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Options
  6. 5 Pin Configuration and Functions
  7. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information RDS Package
    5. 6.5 Thermal Information VCB Package
    6. 6.6 Electrical Characteristics
    7. 6.7 Typical Characteristics
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Pulse Width Modulation (PWM) Operation
      2. 7.3.2 Power Save Mode (PSM) Operation
      3. 7.3.3 Start-Up and Soft Start
      4. 7.3.4 Switch Cycle-by-Cycle Current Limit
      5. 7.3.5 Undervoltage Lockout
      6. 7.3.6 Thermal Shutdown
      7. 7.3.7 Optimized EMI Performance
    4. 7.4 Device Functional Modes
      1. 7.4.1 Enable, Disable, and Output Discharge
      2. 7.4.2 Minimum Duty Cycle and 100% Mode Operation
      3. 7.4.3 Power Good
  9. 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 Setting The Output Voltage
        3. 8.2.2.3 Input Capacitor Selection
        4. 8.2.2.4 Output Capacitor Selection
      3. 8.2.3 Application Curves
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
        1. 8.4.2.1 Thermal Considerations
  10. 9 Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 Third-Party Products Disclaimer
      2. 9.1.2 Development Support
        1. 9.1.2.1 Custom Design With WEBENCH® Tools
    2. 9.2 Documentation Support
      1. 9.2.1 Related Documentation
    3. 9.3 Support Resources
    4. 9.4 Trademarks
    5. 9.5 Electrostatic Discharge Caution
    6. 9.6 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

7.4.2 Minimum Duty Cycle and 100% Mode Operation

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

If the output voltage (VOUT) comes close to the input voltage (VIN), the device enters 100% mode. While the high-side switch is constantly turned on, the low-side switch is switched off. This action is particularly useful in battery-powered applications to achieve longest operation time by taking full advantage of the whole battery voltage range. The difference between VIN and VOUT is determined by the voltage drop across the high-side FET and the DC resistance of the inductor. The minimum VIN that is needed to maintain a specific VOUT value is estimated as:

Equation 3. V I N , m i n = V O U T + I O U T , M A X × R D P

where

  • VIN,min = Minimum input voltage to maintain an output voltage
  • IOUT,MAX = Maximum output current
  • RDP = Resistance from VIN to VOUT, which includes the high-side MOSFET on-resistance and DC resistance of the inductor