SNVSAT9 June 2017 LM25145


  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Description (continued)
  6. Pin Configuration and Functions
    1. 6.1Wettable Flanks
  7. Specifications
    1. 7.1Absolute Maximum Ratings
    2. 7.2ESD Ratings
    3. 7.3Recommended Operating Conditions
    4. 7.4Thermal Information
    5. 7.5Electrical Characteristics
    6. 7.6Switching Characteristics
    7. 7.7Typical Characteristics
  8. Detailed Description
    1. 8.1Overview
    2. 8.2Functional Block Diagram
    3. 8.3Feature Description
      1. 8.3.1 Input Range (VIN)
      2. 8.3.2 Output Voltage Setpoint and Accuracy (FB)
      3. 8.3.3 High-Voltage Bias Supply Regulator (VCC)
      4. 8.3.4 Precision Enable (EN/UVLO)
      5. 8.3.5 Power Good Monitor (PGOOD)
      6. 8.3.6 Switching Frequency (RT, SYNCIN)
        1. Adjust
        2. Synchronization
      7. 8.3.7 Configurable Soft-Start (SS/TRK)
      8. 8.3.8 Voltage-Mode Control (COMP)
      9. 8.3.9 Gate Drivers (LO, HO)
      10. 8.3.10Current Sensing and Overcurrent Protection (ILIM)
      11. 8.3.11OCP Duty Cycle Limiter
    4. 8.4Device Functional Modes
      1. 8.4.1Shutdown Mode
      2. 8.4.2Standby Mode
      3. 8.4.3Active Mode
      4. 8.4.4Diode Emulation Mode
      5. 8.4.5Thermal Shutdown
  9. Application and Implementation
    1. 9.1Application Information
      1. 9.1.1Design and Implementation
      2. 9.1.2Power Train Components
        2. Capacitors
        3. Capacitors
        4. MOSFETs
      3. 9.1.3Control Loop Compensation
      4. 9.1.4EMI Filter Design
    2. 9.2Typical Applications
      1. 9.2.1Design 1 - 20-A High-Efficiency Synchronous Buck Regulator for Telecom Power Applications
        1. Requirements
        2. Design Procedure
        3. Design With WEBENCH® Tools
        4. Curves
      2. 9.2.2Design 2 - High Density, 12-V, 8-A Rail With LDO Low-Noise Auxiliary Output for Industrial Applications
        1. Requirements
        2. Design Procedure
          1. Curves
      3. 9.2.3Design 3 - Powering a Multicore DSP From a 24-V Rail
        1. Requirements
        2. Design Procedure
        3. Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1Layout Guidelines
      1. 11.1.1Power Stage Layout
      2. 11.1.2Gate Drive Layout
      3. 11.1.3PWM Controller Layout
      4. 11.1.4Thermal Design and Layout
      5. 11.1.5Ground Plane Design
    2. 11.2Layout Example
  12. 12Device and Documentation Support
    1. 12.1Device Support
      1. 12.1.1Third-Party Products Disclaimer
      2. 12.1.2Development Support
      3. 12.1.3Custom Design With WEBENCH® Tools
    2. 12.2Documentation Support
      1. 12.2.1Related Documentation
        1. Layout Resources
        2. Design Resources
    3. 12.3Related Links
    4. 12.4Receiving Notification of Documentation Updates
    5. 12.5Community Resources
    6. 12.6Trademarks
    7. 12.7Electrostatic Discharge Caution
    8. 12.8Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • RGY|20
Orderable Information


  • Versatile Synchronous Buck DC-DC Controller
    • Wide Input Voltage Range of 6 V to 42 V
    • Adjustable Output Voltage From 0.8 V to 40 V
  • Meets EN55022 / CISPR 22 EMI Standards
  • Lossless RDS(on) or Shunt Current Sensing
  • Switching Frequency From 100 kHz to 1 MHz
    • SYNC In and SYNC Out Capability
  • 40-ns Minimum On-Time for High VIN / VOUT Ratio
  • 140-ns Minimum Off-Time for Low Dropout
  • 0.8-V Reference With ±1% Feedback Accuracy
  • 7.5-V Gate Drivers for Standard VTH MOSFETs
    • 14-ns Adaptive Dead-Time Control
    • 2.3-A Source and 3.5-A Sink Capability
    • Low-Side Soft-Start for Prebiased Start-Up
  • Adjustable Soft-Start or Optional Voltage Tracking
  • Fast Line and Load Transient Response
    • Voltage-Mode Control With Line Feedforward
    • High Gain-Bandwidth Error Amplifier
  • Precision Enable Input and Open-Drain Power Good Indicator for Sequencing and Control
  • Inherent Protection Features for Robust Design
    • Hiccup Mode Overcurrent Protection
    • Input UVLO With Hysteresis
    • VCC and Gate Drive UVLO Protection
    • Thermal Shutdown Protection With Hysteresis
  • VQFN-20 Package With Wettable Flanks
  • Create a Custom Design Using the LM25145 With WEBENCH® Power Designer


  • Telecom Infrastructure
  • Factory Automation
  • Test and Measurement
  • Industrial Motor Drives


The LM25145 42-V synchronous buck controller is designed to regulate from a high input voltage source or from an input rail subject to high voltage transients, minimizing the need for external surge suppression components. A high-side switch minimum on-time of 40 ns facilitates large step-down ratios, enabling the direct step-down conversion from a 24 V nominal input to low-voltage rails for reduced system complexity and solution cost. The LM25145 continues to operate during input voltage dips as low as 6 V, at nearly 100% duty cycle if needed, making it well suited for high-performance industrial control, robotic, datacom, and RF power amplifier applications.

Forced-PWM (FPWM) operation eliminates frequency variation to minimize EMI, while a user-selectable diode emulation feature lowers current consumption at light-load conditions. Cycle-by-cycle overcurrent protection is accomplished by measuring the voltage drop across the low-side MOSFET or by using an optional current sense resistor. The adjustable switching frequency as high as 1 MHz can be synchronized to an external clock source to eliminate beat frequencies in noise-sensitive applications.

Device Information(1)

LM25145VQFN (20)3.50 mm × 4.50 mm
  1. For all available packages, see the orderable addendum at the end of the data sheet.

Typical Application Circuit and Efficiency Performance, VOUT = 5 V, FSW = 225 kHz

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