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  • LMR514x5 36V, 2.5A / 3.5A, Synchronous Buck Converter With Low IQ

    • SLUSFM4 September   2024 LMR51425 , LMR51435

      PRODUCTION DATA  

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  • LMR514x5 36V, 2.5A / 3.5A, Synchronous Buck Converter With Low IQ
  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison Table
  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
    5. 6.5 Electrical Characteristics
    6. 6.6 System 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  Fixed Frequency Peak Current Mode Control
      2. 7.3.2  Adjustable Output Voltage
      3. 7.3.3  Enable
      4. 7.3.4  Switching Frequency
      5. 7.3.5  Power-Good Flag Output
      6. 7.3.6  Minimum ON-Time, Minimum OFF-Time, and Frequency Foldback
      7. 7.3.7  Bootstrap Voltage
      8. 7.3.8  Overcurrent and Short-Circuit Protection
      9. 7.3.9  Soft Start
      10. 7.3.10 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Shutdown Mode
      2. 7.4.2 Active Mode
      3. 7.4.3 CCM Mode
      4. 7.4.4 Light-Load Operation (PFM Version)
      5. 7.4.5 Light-Load Operation (FPWM Version)
  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 Output Voltage Set-Point
        3. 8.2.2.3 Switching Frequency
        4. 8.2.2.4 Inductor Selection
        5. 8.2.2.5 Output Capacitor Selection
        6. 8.2.2.6 Input Capacitor Selection
        7. 8.2.2.7 Bootstrap Capacitor
        8. 8.2.2.8 Undervoltage Lockout Setpoint
      3. 8.2.3 Application Curves
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
        1. 8.4.1.1 Compact Layout for EMI Reduction
        2. 8.4.1.2 Feedback Resistors
      2. 8.4.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 Development Support
        1. 9.1.1.1 Custom Design With WEBENCH® Tools
    2. 9.2 Documentation Support
      1. 9.2.1 Related Documentation
    3. 9.3 Receiving Notification of Documentation Updates
    4. 9.4 Support Resources
    5. 9.5 Trademarks
    6. 9.6 Electrostatic Discharge Caution
    7. 9.7 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information
    1. 11.1 Tape and Reel Information
  13. IMPORTANT NOTICE

Package Options

Mechanical Data (Package|Pins)
  • DRR|12
    • MPSS085A
Thermal pad, mechanical data (Package|Pins)
  • DRR|12
    • PPTD377
Orderable Information
  • slusfm4_oa
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Data Sheet

LMR514x5 36V, 2.5A / 3.5A, Synchronous Buck Converter With Low IQ

1 Features

  • Functional Safety-Capable
    • Documentation available to aid functional safety system design
  • Configured for rugged industrial applications:
    • Wide input voltage range: 4V to 36V
    • Continuous output current: 2.5A or 3.5A
    • ±1.0% tolerance voltage reference at room temperature
    • Minimum switching-on time: 75ns (typical)
    • Low quiescent current: 25µA
    • Adjustable frequency: 200kHz to 1.1MHz
    • Frequency spread spectrum
    • Protection features:
      • Precision enable input
      • Open-drain PGOOD
      • VIN undervoltage lockout (UVLO)
      • Cycle-by-cycle current limiting
      • Short-circuit protection with hiccup mode
      • Thermal shutdown
  • Small design size and ease of use
    • Integrated synchronous rectification
    • Internal compensation for ease of use
    • WSON-12 package
  • PFM and FPWM options in pin-to-pin compatible package
  • Create a custom design using the LMR514x5 with the WEBENCH® Power Designer

2 Applications

  • Major appliances
  • PLC, DCS, and PAC
  • Test and measurement instrumentation
  • Power delivery

3 Description

The LMR514x5 is a wide-VIN, easy-to-use, synchronous buck converter capable of driving up to 2.5A or 3.5A load current. With a wide input range of 4V to 36V, the device is designed for a wide range of industrial applications for power conditioning from an unregulated source.

The LMR514x5 features adjustable switching frequency from 200kHz to 1.1MHz with an external resistor, which provides the flexibility to optimize either efficiency or external component size. The device has pulse frequency modulation (PFM version) to realize high efficiency at light load, and forced pulse width modulation (FPWM version) to achieve constant frequency, and small output voltage ripple over the full load range. Soft-start and compensation circuits are implemented internally, which allows the device to be used with minimum external components.

The device has built-in protection features, such as cycle-by-cycle current limit, hiccup mode short-circuit protection, and thermal shutdown in case of excessive power dissipation. The LMR514x5 is available in a WSON-12 package.

Device Information
PART NUMBER(1)CURRENTPACKAGE(2)BODY SIZE (NOM)
LMR514252.5ADRR (WSON, 12)3.00mm × 3.00mm
LMR514353.5A
(1) See the Device Comparison Table.
(2) For more information, see Section 11.
LMR51425 LMR51435 Simplified SchematicSimplified Schematic
LMR51425 LMR51435 Efficiency vs Output Current VOUT = 5V, 500kHzEfficiency vs Output Current VOUT = 5V, 500kHz

 
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