SNVSC10 March   2022 LM25143

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Description (continued)
  6. 6 Device Comparison Table
  7. 7 Pin Configuration and Functions
  8. 8 Specifications
    1. 8.1 Absolute Maximum Ratings
    2. 8.2 ESD Ratings
    3. 8.3 Recommended Operating Conditions
    4. 8.4 Thermal Information
    5. 8.5 Electrical Characteristics
    6. 8.6 Switching Characteristics
    7. 8.7 Typical Characteristics
  9. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1  Input Voltage Range (VIN)
      2. 9.3.2  High-Voltage Bias Supply Regulator (VCC, VCCX, VDDA)
      3. 9.3.3  Enable (EN1, EN2)
      4. 9.3.4  Power-Good Monitor (PG1, PG2)
      5. 9.3.5  Switching Frequency (RT)
      6. 9.3.6  Clock Synchronization (DEMB)
      7. 9.3.7  Synchronization Out (SYNCOUT)
      8. 9.3.8  Spread Spectrum Frequency Modulation (DITH)
      9. 9.3.9  Configurable Soft Start (SS1, SS2)
      10. 9.3.10 Output Voltage Setpoint (FB1, FB2)
      11. 9.3.11 Minimum Controllable On Time
      12. 9.3.12 Error Amplifier and PWM Comparator (FB1, FB2, COMP1, COMP2)
      13. 9.3.13 Slope Compensation
      14. 9.3.14 Inductor Current Sense (CS1, VOUT1, CS2, VOUT2)
        1. 9.3.14.1 Shunt Current Sensing
        2. 9.3.14.2 Inductor DCR Current Sensing
      15. 9.3.15 Hiccup Mode Current Limiting (RES)
      16. 9.3.16 High-Side and Low-Side Gate Drivers (HO1/2, LO1/2, HOL1/2, LOL1/2)
      17. 9.3.17 Output Configurations (MODE, FB2)
        1. 9.3.17.1 Independent Dual-Output Operation
        2. 9.3.17.2 Single-Output Interleaved Operation
        3. 9.3.17.3 Single-Output Multiphase Operation
    4. 9.4 Device Functional Modes
      1. 9.4.1 Standby Modes
      2. 9.4.2 Diode Emulation Mode
      3. 9.4.3 Thermal Shutdown
  10. 10Application and Implementation
    1. 10.1 Application Information
      1. 10.1.1 Power Train Components
        1. 10.1.1.1 Buck Inductor
        2. 10.1.1.2 Output Capacitors
        3. 10.1.1.3 Input Capacitors
        4. 10.1.1.4 Power MOSFETs
        5. 10.1.1.5 EMI Filter
      2. 10.1.2 Error Amplifier and Compensation
    2. 10.2 Typical Applications
      1. 10.2.1 Design 1 – 5-V and 3.3-V Dual-Output Buck Regulator for Computing Applications
        1. 10.2.1.1 Design Requirements
        2. 10.2.1.2 Detailed Design Procedure
          1. 10.2.1.2.1 Custom Design With WEBENCH® Tools
          2. 10.2.1.2.2 Custom Design With Excel Quickstart Tool
          3. 10.2.1.2.3 Inductor Calculation
          4. 10.2.1.2.4 Current-Sense Resistance
          5. 10.2.1.2.5 Output Capacitors
          6. 10.2.1.2.6 Input Capacitors
          7. 10.2.1.2.7 Compensation Components
        3. 10.2.1.3 Application Curves
      2. 10.2.2 Design 2 – Two-Phase, 15-A, 2.1-MHz Single-Output Buck Regulator for Server Applications
        1. 10.2.2.1 Design Requirements
        2. 10.2.2.2 Detailed Design Procedure
        3. 10.2.2.3 Application Curves
      3. 10.2.3 Design 3 – Two-Phase, 50-A, 300-kHz Single-Output Buck Regulator for ASIC Power Applications
        1. 10.2.3.1 Design Requirements
        2. 10.2.3.2 Detailed Design Procedure
        3. 10.2.3.3 Application Curves
  11. 11Power Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
      1. 12.1.1 Power Stage Layout
      2. 12.1.2 Gate-Drive Layout
      3. 12.1.3 PWM Controller Layout
      4. 12.1.4 Thermal Design and Layout
      5. 12.1.5 Ground Plane Design
    2. 12.2 Layout Example
  13. 13Device and Documentation Support
    1. 13.1 Device Support
      1. 13.1.1 Third-Party Products Disclaimer
      2. 13.1.2 Development Support
        1. 13.1.2.1 Custom Design With WEBENCH® Tools
    2. 13.2 Documentation Support
      1. 13.2.1 Related Documentation
        1. 13.2.1.1 PCB Layout Resources
        2. 13.2.1.2 Thermal Design Resources
    3. 13.3 Receiving Notification of Documentation Updates
    4. 13.4 Support Resources
    5. 13.5 Trademarks
    6. 13.6 Electrostatic Discharge Caution
    7. 13.7 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

Package Options

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

10.2.3.1 Design Requirements

Table 10-6 shows the intended input, output, and performance parameters for this design example.

Table 10-6 Design Parameters
Design Parameter Value
Nominal input voltage 24 V
Input voltage range (steady state) 18 V to 36 V
Output voltage 5 V
Thermal design current (TDC) 35 A
Electrical design current (EDC) 50 A
Switching frequency 300 kHz
Output voltage regulation ±1%
Shutdown current 4 µA

The switching frequency is set at 300 kHz by resistor RRT. In terms of control loop performance, the target loop crossover frequency is 45 kHz with a phase margin greater than 50°. The output voltage soft-start time is set at 3 ms by a 100-nF soft-start capacitor. FPWM operation provides constant switching frequency over the full load current range for predictable EMI performance and optimal load transient response.

The selected buck regulator powertrain components are cited in Table 10-7, 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 10.1.1.4. This design uses a low-DCR composite inductor and ceramic output capacitor implementation.

Table 10-7 List of Materials for Application Circuit 3
Ref Des Qty Specification Manufacturer(1) Part Number
CIN 6 10 µF, 50 V, X7R, 1210, ceramic TDK CNA6P1X7R1H106K
AVX 12105C106K4T2A
10 µF, 50 V, X7R, 1206, ceramic TDK CGA5L1X7R1H106K
CO 8 47 µF, 6.3 V, X7R, 1210, ceramic Murata GCM32ER70J476KE19L
6 100 µF, 6.3 V, X7S, 1210, ceramic Murata GRT32EC70J107ME13L
CO(BULK) 1 220 µF, 10 V, 25 mΩ, 7343, polymer tantalum Kemet T598D227M010ATE025
AVX TCQD227M010R0025E
LO1, LO2 2 1.5 µH, 1.28 mΩ, 46.7 A, 13.3 × 12.8 × 8 mm Cyntec VCUD128T-1R5MS8
1.5 µH, 2.3 mΩ, 35 A, 13.5 × 12.6 × 6.5 mm Cyntec VCMV136E-1R5MN2
1.5 µH, 2.8 mΩ, 32.8 A, 13 × 12.5 × 6.5 mm TDK SPM12565VT-1R5M-D
1.5 µH, 2.3 mΩ, 55.3 A, 13.5 × 12.5 × 6.2 mm Würth Elektronik 744373965015
Q1, Q3 2 60 V, 11 mΩ, 4.5 nC, DFN5 Onsemi NVMFS5C673NL
Q2, Q4 2 60 V, 2.6 mΩ, 24 nC, DFN5 Onsemi NVMFS5C628NL
U1 1 LM25143 42-V dual-channel/phase synchronous buck controller Texas Instruments LM25143RHAR