SNVSAG3B November   2015  – December 2024 LMR14030-Q1

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Switching Characteristics
    7. 5.7 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1  Fixed Frequency Peak Current Mode Control
      2. 6.3.2  Slope Compensation
      3. 6.3.3  Sleep-mode
      4. 6.3.4  Low Dropout Operation and Bootstrap Voltage (BOOT)
      5. 6.3.5  Adjustable Output Voltage
      6. 6.3.6  Enable and Adjustable Undervoltage Lockout
      7. 6.3.7  External Soft-start
      8. 6.3.8  Switching Frequency and Synchronization (RT/SYNC)
      9. 6.3.9  Power Good (PGOOD)
      10. 6.3.10 Over Current and Short Circuit Protection
      11. 6.3.11 Overvoltage Protection
      12. 6.3.12 Thermal Shutdown
    4. 6.4 Device Functional Modes
      1. 6.4.1 Shutdown Mode
      2. 6.4.2 Active Mode
      3. 6.4.3 CCM Mode
      4. 6.4.4 Light Load Operation
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
        1. 7.2.2.1 Output Voltage Set-Point
        2. 7.2.2.2 Switching Frequency
        3. 7.2.2.3 Output Inductor Selection
        4. 7.2.2.4 Output Capacitor Selection
        5. 7.2.2.5 Schottky Diode Selection
        6. 7.2.2.6 Input Capacitor Selection
        7. 7.2.2.7 Bootstrap Capacitor Selection
        8. 7.2.2.8 Soft-start Capacitor Selection
      3. 7.2.3 Application Curves
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
      2. 7.4.2 Layout Example
  9. 8 Device and Documentation Support
    1. 8.1 Device Support
      1. 8.1.1 Third-Party Products Disclaimer
    2. 8.2 Documentation Support
      1. 8.2.1 Related Documentation
      2. 8.2.2 Related Products
    3. 8.3 Receiving Notification of Documentation Updates
    4. 8.4 Support Resources
    5. 8.5 Trademarks
    6. 8.6 Electrostatic Discharge Caution
    7. 8.7 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

パッケージ・オプション

メカニカル・データ（パッケージ｜ピン）
サーマルパッド・メカニカル・データ
発注情報

6.3.1 Fixed Frequency Peak Current Mode Control

The following operating description of the LMR14030-Q1 refer to the Section 6.2 and to the waveforms in Figure 6-1. LMR14030-Q1 output voltage is regulated by turning on the high-side N-MOSFET with controlled ON time. During high-side switch ON time, the SW pin voltage swings up to approximately VIN, and the inductor current iL increase with linear slope (VIN – VOUT) / L. When high-side switch is off, inductor current discharges through freewheel diode with a slope of –VOUT / L. The control parameter of Buck converter is defined as Duty Cycle D = tON / TSW, where tON is the high-side switch ON time and TSW is the switching period. The regulator control loop maintains a constant output voltage by adjusting the duty cycle D. In an ideal Buck converter, where losses are ignored, D is proportional to the output voltage and inversely proportional to the input voltage: D = VOUT / VIN.

LMR14030-Q1 SW Node and Inductor Current Waveforms in Continuous Conduction Mode (CCM)Figure 6-1 SW Node and Inductor Current Waveforms in Continuous Conduction Mode (CCM)

The LMR14030-Q1 employs fixed frequency peak current mode control. A voltage feedback loop is used to get accurate DC voltage regulation by adjusting the peak current command based on voltage offset. The peak inductor current is sensed from the high-side switch and compared to the peak current to control the ON time of the high-side switch. The voltage feedback loop is internally compensated, which allows for fewer external components, makes it easy to design, and provides stable operation with almost any combination of output capacitors. The regulator operates with fixed switching frequency at normal load condition. At very light load, the LMR14030-Q1 will operate in Sleep-mode to maintain high efficiency and the switching frequency will decrease with reduced load current.