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  • LM25148-Q1 42V, Automotive, Synchronous, Buck DC/DC Controller With Ultra-Low IQ and Dual Random Spread Spectrum

    • SNVSC03B June   2021  – February 2025 LM25148-Q1

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  • LM25148-Q1 42V, Automotive, Synchronous, Buck DC/DC Controller With Ultra-Low IQ and Dual Random Spread Spectrum
  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Description (continued)
  6. 5 Orderable Part Numbers
  7. 6 Pin Configuration and Functions
    1. 6.1 Wettable Flanks
  8. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings 
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Typical Characteristics
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Input Voltage Range (VIN)
      2. 8.3.2  High-Voltage Bias Supply Regulator (VCC, VCCX, VDDA)
      3. 8.3.3  Precision Enable (EN)
      4. 8.3.4  Power-Good Monitor (PG)
      5. 8.3.5  Switching Frequency (RT)
      6. 8.3.6  Dual Random Spread Spectrum (DRSS)
      7. 8.3.7  Soft Start
      8. 8.3.8  Output Voltage Setpoint (FB)
      9. 8.3.9  Minimum Controllable On Time
      10. 8.3.10 Error Amplifier and PWM Comparator (FB, EXTCOMP)
      11. 8.3.11 Slope Compensation
      12. 8.3.12 Inductor Current Sense (ISNS+, VOUT)
        1. 8.3.12.1 Shunt Current Sensing
        2. 8.3.12.2 Inductor DCR Current Sensing
      13. 8.3.13 Hiccup Mode Current Limiting
      14. 8.3.14 High-Side and Low-Side Gate Drivers (HO, LO)
      15. 8.3.15 Output Configurations (CNFG)
      16. 8.3.16 Single-Output Dual-Phase Operation
    4. 8.4 Device Functional Modes
      1. 8.4.1 Sleep Mode
      2. 8.4.2 Pulse Frequency Modulation and Synchronization (PFM/SYNC)
      3. 8.4.3 Thermal Shutdown
  10. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Power Train Components
        1. 9.1.1.1 Buck Inductor
        2. 9.1.1.2 Output Capacitors
        3. 9.1.1.3 Input Capacitors
        4. 9.1.1.4 Power MOSFETs
        5. 9.1.1.5 EMI Filter
      2. 9.1.2 Error Amplifier and Compensation
    2. 9.2 Typical Applications
      1. 9.2.1 Design 1 – High Efficiency 2.1MHz Synchronous Buck Regulator
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
          1. 9.2.1.2.1 Custom Design with WEBENCH® Tools
          2. 9.2.1.2.2 Buck Inductor
          3. 9.2.1.2.3 Current-Sense Resistance
          4. 9.2.1.2.4 Output Capacitors
          5. 9.2.1.2.5 Input Capacitors
          6. 9.2.1.2.6 Frequency Set Resistor
          7. 9.2.1.2.7 Feedback Resistors
          8. 9.2.1.2.8 Compensation Components
        3. 9.2.1.3 Application Curves
      2. 9.2.2 Design 2 – High Efficiency 440-kHz Synchronous Buck Regulator
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
        3. 9.2.2.3 Application Curves
      3. 9.2.3 Design 3 – Dual-Phase 400-kHz 20-A Synchronous Buck Regulator
        1. 9.2.3.1 Design Requirements
        2. 9.2.3.2 Detailed Design Procedure
        3. 9.2.3.3 Application Curves
    3. 9.3 Power Supply Recommendations
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
        1. 9.4.1.1 Power Stage Layout
        2. 9.4.1.2 Gate-Drive Layout
        3. 9.4.1.3 PWM Controller Layout
        4. 9.4.1.4 Thermal Design and Layout
        5. 9.4.1.5 Ground Plane Design
      2. 9.4.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Device Support
      1. 10.1.1 Development Support
        1. 10.1.1.1 Custom Design with WEBENCH® Tools
    2. 10.2 Documentation Support
      1. 10.2.1 Related Documentation
        1. 10.2.1.1 PCB Layout Resources
        2. 10.2.1.2 Thermal Design Resources
    3. 10.3 Receiving Notification of Documentation Updates
    4. 10.4 Support Resources
    5. 10.5 Trademarks
    6. 10.6 Electrostatic Discharge Caution
    7. 10.7 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information
  14. IMPORTANT NOTICE

Package Options

Mechanical Data (Package|Pins)
  • RGY|24
    • MPQF143E
Thermal pad, mechanical data (Package|Pins)
  • RGY|24
    • QFND668
Orderable Information
  • snvsc03b_oa
  • snvsc03b_pm
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Data Sheet

LM25148-Q1 42V, Automotive, Synchronous, Buck DC/DC Controller With Ultra-Low IQ and Dual Random Spread Spectrum

1 Features

  • AEC-Q100 qualified for automotive applications:
    • Device temperature grade 1: –40°C to +125°C ambient operating temperature
  • Functional Safety-Capable
    • Documentation available to aid functional safety system design
  • Integrated EMI mitigation
    • Selectable dual random spread spectrum (DRSS) feature for enhanced EMI performance across low and high-frequency bands
    • Optimized for CISPR 25 Class 5 requirements
  • Versatile synchronous buck DC/DC controller
    • Wide input voltage range of 3.5V to 42V
    • 1% accurate, fixed 3.3V, 5V, 12V, or adjustable output from 0.8V to 36V
    • 150°C maximum junction temperature
    • Shutdown mode current of 2.3µA
    • No-load sleep current of 9.5µA
    • Internal soft-start ramp of 3ms
    • Stackable up to two phases
    • Internal bootstrap diode
  • Switching frequency from 100kHz to 2.2MHz
    • SYNC in and SYNC out capability
  • Inherent protection features for robust design
    • Internal hiccup mode overcurrent protection
    • ENABLE and PGOOD functions
    • VCC, VDDA, and gate-drive UVLO protection
    • Internal or external loop compensation
    • Thermal shutdown protection with hysteresis
  • Create a custom design using the LM25148-Q1 with WEBENCH® Power Designer

2 Applications

  • Automotive electronic systems
  • Advanced Driver Assistance Systems (ADAS)
  • Infotainment and clusters
  • Body electronics

3 Description

The LM25148-Q1 is a 42V, ultra-low IQ synchronous buck DC/DC controller for high-current, single-output applications. The controller uses a peak current-mode control architecture for easy loop compensation, fast transient response, and excellent load and line regulation. The LM25148-Q1 can be set up in dual-phase mode (paralleled output) with accurate current sharing for high-current applications. The device can operate at input voltages as low as 3.5V, at nearly 100% duty cycle if needed.

The LM25148-Q1 has a unique EMI reduction 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.

Package Information
PART NUMBER PACKAGE(1) PACKAGE SIZE(2)
LM25148-Q1 RGY (VQFN, 24) 5.50mm × 3.50mm
(1) For more information, see Section 12.
(2) The package size (length × width) is a nominal value and includes pins, where applicable.
LM25148-Q1 Typical Application SchematicTypical Application Schematic
LM25148-Q1 CISPR 25 EMI Performance - 150kHz to 30MHzCISPR 25 EMI Performance - 150kHz to 30MHz

 
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