SNVSCF4 July   2025 LM25139-Q1

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
    1. 4.1 Wettable Flanks
  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 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  Input Voltage Range (VIN )
      2. 6.3.2  High-Voltage Bias Supply Regulator (VCC)
      3. 6.3.3  Precision Enable (EN)
      4. 6.3.4  Power-Good Monitor (PG)
      5. 6.3.5  Switching Frequency (RT)
      6. 6.3.6  Dual Random Spread Spectrum (DRSS)
      7. 6.3.7  Soft Start
      8. 6.3.8  Output Voltage Setpoint (FB)
      9. 6.3.9  Minimum Controllable On Time
      10. 6.3.10 Error Amplifier and PWM Comparator (FB)
      11. 6.3.11 Slope Compensation
      12. 6.3.12 Inductor Current Sense (ISNS, VOUT)
        1. 6.3.12.1 Shunt Current Sensing
        2. 6.3.12.2 Inductor DCR Current Sensing
        3. 6.3.12.3 Hiccup-Mode Current Limiting
    4. 6.4 Device Functional Modes
      1. 6.4.1 Sleep Mode
      2. 6.4.2 Forced PWM and Synchronization (FPWM/SYNC)
      3. 6.4.3 Thermal Shutdown
  8. 7 Application and Implementation
    1. 7.1 Application Information
      1. 7.1.1 Power Train Components
        1. 7.1.1.1 Buck Inductor
        2. 7.1.1.2 Output Capacitors
        3. 7.1.1.3 Input Capacitors
        4. 7.1.1.4 Power MOSFETs
        5. 7.1.1.5 EMI Filter
      2. 7.1.2 Error Amplifier and Compensation
    2. 7.2 Typical Applications
      1. 7.2.1 Design 1 – High Efficiency 2.2MHz Synchronous Buck Regulator
        1. 7.2.1.1 Design Requirements
        2. 7.2.1.2 Detailed Design Procedure
          1. 7.2.1.2.1 Custom Design With WEBENCH® Tools
          2. 7.2.1.2.2 Buck Inductor
          3. 7.2.1.2.3 Current-Sense Components
          4. 7.2.1.2.4 Output Capacitors
          5. 7.2.1.2.5 Input Capacitors
          6. 7.2.1.2.6 Frequency Set Resistor
          7. 7.2.1.2.7 Feedback Resistors
          8. 7.2.1.2.8 Compensation Components
        3. 7.2.1.3 Application Curves
      2. 7.2.2 Design 2 – High-Efficiency, 440kHz, Synchronous Buck Regulator
        1. 7.2.2.1 Design Requirements
        2. 7.2.2.2 Detailed Design Procedure
        3. 7.2.2.3 Application Curves
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
        1. 7.4.1.1 Power Stage Layout
        2. 7.4.1.2 Gate Drive Layout
        3. 7.4.1.3 PWM Controller Layout
        4. 7.4.1.4 Thermal Design and Layout
        5. 7.4.1.5 Ground Plane Design
      2. 7.4.2 Layout Example
  9. 8 Device and Documentation Support
    1. 8.1 Device Support
      1. 8.1.1 Development Support
        1. 8.1.1.1 Custom Design With WEBENCH® Tools
    2. 8.2 Documentation Support
      1. 8.2.1 Related Documentation
        1. 8.2.1.1 Low-EMI Design Resources
        2. 8.2.1.2 Thermal Design Resources
        3. 8.2.1.3 PCB Layout Resources
    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

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

3 Description

The LM25139-Q1 is a 42V, synchronous, buck DC/DC controller with ultra-low IQ for single-output, high-current regulator circuits. Deriving from a family of wide-VIN range automotive controllers, the device uses a peak current-mode control architecture for fast transient response, convenient loop compensation, and excellent load and line regulation performance.

A high-side switch minimum on time of 25ns provides large step-down ratios, enabling the direct conversion from 12V and 24V automotive inputs to low-voltage rails for reduced system design cost and complexity. The LM25139-Q1 continues to operate during input voltage dips as low as 4V, at nearly 100% duty cycle if needed, making the device an excellent choice for high-performance, automotive battery applications.

The LM25139-Q1 comes in a thermally enhanced, 16-pin VQFN package with wettable flank pins and an exposed pad to aid in thermal dissipation.

Package Information
PART NUMBER PACKAGE(1) PACKAGE SIZE(2)
LM25139-Q1 RGT (VQFN, 16) 3mm × 3mm
(1) For more information, see Section 10.
(2) The package size (length × width) is a nominal value and includes pins, where applicable.
LM25139-Q1 Typical SchematicTypical Schematic
LM25139-Q1 Typical Efficiency, VOUT = 3.3V, FSW = 440kHzTypical Efficiency, VOUT = 3.3V, FSW = 440kHz

Several features are included to simplify compliance with CISPR 25 automotive EMI requirements. Adaptively timed, high-current MOSFET gate drivers minimize body diode conduction during switching transitions, reducing switching losses while also improving thermal and EMI performance at high input voltage and high switching frequency. Resistor-adjustable switching frequency as high as 3.2MHz can be synchronized to an external clock source to eliminate beat frequencies in noise-sensitive applications.

To further improves the EMI signature, the LM25139-Q1 controller has a unique feature known as dual random spread spectrum (DRSS). Combining low-frequency triangular and high-frequency random modulations mitigates EMI disturbances across lower and higher frequency bands, respectively. This hybrid technique aligns with the multiple resolution bandwidth (RBW) settings specified in industry-standard EMC tests.

Additional features of the LM25139-Q1 include –40°C to 150°C junction temperature operation, user-selectable PFM mode for lower current consumption at light-load conditions, open-drain power-good indicator for fault reporting and output monitoring, precision enable input, monotonic start-up into prebiased load, integrated VCC bias supply regulator and bootstrap diode, internal 3ms soft-start time, hiccup-mode overload protection, and thermal shutdown protection with automatic recovery.

The LM25139-Q1 controller is qualified to AEC-Q100 grade 1 for automotive applications. The wide input voltage range, low quiescent current consumption, high-temperature operation, low minimum on-time, low EMI signature, low component count, and 9mm2 IC size provide an excellent point-of-load regulator choice for applications requiring enhanced robustness and cost advantages.