ZHCSNC7 December   2021 LM25148

PRODUCTION DATA  

  1. 1 特性
  2. 2 应用
  3. 3 说明
  4. 4 Revision History
  5. 5 说明（续）
  6. 6 Pin Configuration and Functions
  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 Custom Design With Excel Quickstart Tool
          3. 9.2.1.2.3 Buck Inductor
          4. 9.2.1.2.4 Current-Sense Resistance
          5. 9.2.1.2.5 Output Capacitors
          6. 9.2.1.2.6 Input Capacitors
          7. 9.2.1.2.7 Frequency Set Resistor
          8. 9.2.1.2.8 Feedback Resistors
          9. 9.2.1.2.9 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
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
      1. 11.1.1 Power Stage Layout
      2. 11.1.2 Gate-Drive Layout
      3. 11.1.3 PWM Controller Layout
      4. 11.1.4 Thermal Design and Layout
      5. 11.1.5 Ground Plane Design
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Development Support
        1. 12.1.1.1 Custom Design With WEBENCH® Tools
    2. 12.2 Documentation Support
      1. 12.2.1 Related Documentation
        1. 12.2.1.1 PCB Layout Resources
        2. 12.2.1.2 Thermal Design Resources
    3. 12.3 接收文档更新通知
    4. 12.4 支持资源
    5. 12.5 Trademarks
    6. 12.6 Electrostatic Discharge Caution
    7. 12.7 术语表
  13. 13Mechanical, Packaging, and Orderable Information

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9.2.3.1 Design Requirements

Table 9-6 shows the intended input, output, and performance parameters for this design example.

Table 9-6 Design Parameters
DESIGN PARAMETER VALUE
Input voltage range (steady-state) 8 V to 36 V
Min transient input voltage 4 V
Max transient input voltage 40 V
Output voltage 3.3 V
Output current 20 A
Switching frequency 400 kHz
Output voltage regulation ±1%
Standby current, no-load 44 µA
Shutdown current 4.6 µA
Soft-start time 3 ms

The switching frequency is set at 400 kHz by resistors RRT1 and RRT2. The selected buck regulator powertrain components are cited in Table 9-7, and many of the components are available from multiple vendors. The MOSFETs in particular are chosen for both lowest conduction and switching power loss, as discussed in detail in Section 9.1.1.4.

Table 9-7 List of Materials for Application Circuit 3
REFERENCE DESIGNATOR QTY SPECIFICATION MANUFACTURER PART NUMBER
CIN 4 10 µF, 50 V, X7R, 1210, ceramic AVX 12105C106K4Z2A
TDK C3225X7R1H106K250AC
Murata GRM32ER71H106KA12L
CO 8 47 µF, 6.3 V, X7R, 1210, ceramic Murata GCM32ER70J476KE19L
47 µF, 10 V, X7S, 1210, ceramic TDK CGA6P1X7S1A476M250AC
4 100 µF, 6.3 V, X7S, 1210, ceramic Murata GRT32EC70J107ME13
LO1, LO2 2 2.2 μH, 4.5 mΩ, 32 A, 11.3 × 10 × 6 mm Coilcraft XKL1060-222MEC
2.2 μH, 4.3 mΩ, 12.5 A, 6.7 × 6.5 × 6.1 mm Coilcraft XGL6060-222MEC
2.2 µH, 6.5 mΩ, 10 A, 10 × 11 × 3.8 mm Würth Electronik 74437368022
Q1, Q3 2 40 V, 4.7 mΩ, 12 nC, SON 5 × 6 Texas Instruments CSD18503Q5A
Q2, Q4 2 40 V, 2.7 mΩ, 35 nC, SON 5 × 6 Texas Instruments CSD18511Q5A
RS1, RS2 2 Shunt, 4 mΩ, 0508, 1 W Susumu

KRL2012E-M-R004-F-T5
U1, U2 2 LM25148 42-V synchronous buck controller Texas Instruments LM25148RGYR