JAJSRP9 September   2024

ADVANCE INFORMATION  

  1.   1
  2. 1 特長
  3. 2 アプリケーション
  4. 3 説明
  5. 4 Device Options
  6. 5 Pin Configuration and Functions
  7. 6 Specifications
    1. 6.1 Absolute Maximum Rating
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 I2C Interface Timing 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 Frequency Modulation (PFM)
      2. 7.3.2 Forced PWM Mode
      3. 7.3.3 Low Dropout Operation (100% Duty Cycle)
      4. 7.3.4 Soft Start
      5. 7.3.5 Switch Current Limit and HICCUP Short-Circuit Protection
      6. 7.3.6 Undervoltage Lockout
      7. 7.3.7 Thermal Warning and Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Enable and Disable (EN)
      2. 7.4.2 Output Discharge
      3. 7.4.3 Power Good (PG)
      4. 7.4.4 Voltage Setting and Mode Selection (VSET/MODE)
    5. 7.5 Programming
      1. 7.5.1 Serial Interface Description
      2. 7.5.2 Standard-, Fast-, and Fast-Mode Plus Protocol
      3. 7.5.3 HS Mode Protocol
      4. 7.5.4 I2C Update Sequence
      5. 7.5.5 I2C Register Reset
  9. 8 Register Map
    1. 8.1 Target Address Byte
    2. 8.2 Register Address Byte
    3. 8.3 VOUT Register 1
    4. 8.4 VOUT Register 2
    5. 8.5 CONTROL Register
    6. 8.6 STATUS Register
  10. 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
    3. 9.3 Power Supply Recommendations
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
      2. 9.4.2 Layout Example
        1. 9.4.2.1 Thermal Considerations
  11. 10Device and Documentation Support
    1. 10.1 Device Support
      1. 10.1.1 サード・パーティ製品に関する免責事項
      2. 10.1.2 Development Support
        1. 10.1.2.1 Custom Design With WEBENCH® Tools
    2. 10.2 Documentation Support
      1. 10.2.1 Related Documentation
    3. 10.3 ドキュメントの更新通知を受け取る方法
    4. 10.4 サポート・リソース
    5. 10.5 Trademarks
    6. 10.6 静電気放電に関する注意事項
    7. 10.7 用語集
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information
    1. 12.1 Tape and Reel Information

7.3.3 Low Dropout Operation (100% Duty Cycle)

The device offers a low dropout operation by entering 100% duty cycle mode if the input voltage comes close to the target output voltage. In this mode, the high-side MOSFET switch is constantly turned on. This is particularly useful in battery-powered applications to achieve the longest operation time by taking full advantage of the whole battery voltage range. The minimum input voltage to maintain a minimum output voltage is given by:
Equation 2. V I N , M I N =   V O U T +   R D S ( O N ) +   R L I O U T , M A X

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).