SNVSC03A June   2021  – February 2023 LM25148-Q1

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Description (continued)
  6. 6 Pin Configuration and Functions
    1. 6.1 Wettable Flanks
  7. 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
  8. 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
  9. 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 2.1-MHz 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
  10. 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
  11. 11Mechanical, Packaging, and Orderable Information

Package Options

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

9.2.1.1 Design Requirements

#GUID-5115867A-38C8-4BA7-9529-B8FB2787F84A/SNVSB29621 shows the intended input, output, and performance parameters for this automotive design example. Refer to the LM25149-Q1EVM-2100 evaluation module.

Table 9-2 Design Parameters
DESIGN PARAMETERVALUE
Input voltage range (steady state)8 V to 18 V
Min transient input voltage (cold crank)5.5 V
Max transient input voltage (load dump)36 V
Output voltage5 V
Output current8 A
Switching frequency2.1 MHz
Output voltage regulation±1%
Standby current, no-load9.9 µA
Shutdown current2.3 µA
Soft-start time3 ms

The switching frequency is set at 2.1 MHz by resistor RRT. In terms of control loop performance, the target loop crossover frequency is 60 kHz with a phase margin greater than 50°.

The selected buck regulator powertrain components are cited in #GUID-5115867A-38C8-4BA7-9529-B8FB2787F84A/SNVSB29622, and many of the components are available from multiple vendors. The MOSFETs in particular are chosen for lowest total conduction and switching power loss.. This design uses a low-DCR composite inductor, and ceramic output capacitors.

Table 9-3 List of Materials for Application Circuit 1
REFERENCE DESIGNATORQTYSPECIFICATIONMANUFACTURERPART NUMBER
CIN210 µF, 50 V, X7S, 1210, ceramic, AEC-Q200Taiyo YudenUMJ325KB7106KMHT
MurataGCM32EC71H106KA03
TDKCGA6P3X7S1H106K250AB
CO447 µF, 6.3 V, X7R, 1210, ceramic, AEC-Q200MurataGCM32ER70J476KE19L
Taiyo YudenJMK325B7476KMHTR
47 µF, 10 V, X7S, 1210, ceramic, AEC-Q200TDKCGA6P1X7S1A476M250AC
LO10.56 μH, 3.6 mΩ, 13 A, 6.6 × 6.6 × 4.8 mm, AEC-Q200Würth Electronik744373490056
0.68 µH, 2.9 mΩ, 22 A, 6.7 × 6.5 × 3.1 mm, AEC-Q200ColicraftXGL6030-681
Q1, Q2 2 40 V, 4.6 mΩ, 7 nC, SON 5 × 6, AEC-Q101 Infineon IAUC60N04S6L039
RS1Shunt, 5 mΩ, 0508, 1 W, AEC-Q200Susumu

KRL2012E-M-R005-F-T5

U11LM25148-Q1 42-V synchronous buck controller, AEC-Q100Texas InstrumentsLM25148QRGYRQ1